config_documentation.md

<!-- Document auto-generated by scripts-dev/gen_config_documentation.py -->

# Configuring Synapse

This is intended as a guide to the Synapse configuration. The behavior of a Synapse instance can be modified
through the many configuration settings documented here — each config option is explained,
including what the default is, how to change the default and what sort of behaviour the setting governs.
Also included is an example configuration for each setting. If you don't want to spend a lot of time
thinking about options, the config as generated sets sensible defaults for all values. Do note however that the
database defaults to SQLite, which is not recommended for production usage. You can read more on this subject
[here](../../setup/installation.md#using-postgresql).

## Config Conventions

Configuration options that take a time period can be set using a number
followed by a letter. Letters have the following meanings:

* `s` = second
* `m` = minute
* `h` = hour
* `d` = day
* `w` = week
* `y` = year

For example, setting `redaction_retention_period: 5m` would remove redacted
messages from the database after 5 minutes, rather than 5 months.

In addition, configuration options referring to size use the following suffixes:

* `K` = KiB, or 1024 bytes
* `M` = MiB, or 1,048,576 bytes
* `G` = GiB, or 1,073,741,824 bytes
* `T` = TiB, or 1,099,511,627,776 bytes

For example, setting `max_avatar_size: 10M` means that Synapse will not accept files larger than 10,485,760 bytes
for a user avatar.

## Config Validation

The configuration file can be validated with the following command:
```bash
python -m synapse.config read <config key to print> -c <path to config>
```

To validate the entire file, omit `read <config key to print>`:
```bash
python -m synapse.config -c <path to config>
```

To see how to set other options, check the help reference:
```bash
python -m synapse.config --help
```

### YAML
The configuration file is a [YAML](https://yaml.org/) file, which means that certain syntax rules
apply if you want your config file to be read properly. A few helpful things to know:
* `#` before any option in the config will comment out that setting and either a default (if available) will
   be applied or Synapse will ignore the setting. Thus, in example #1 below, the setting will be read and
   applied, but in example #2 the setting will not be read and a default will be applied.

   Example #1:
   ```yaml
   pid_file: DATADIR/homeserver.pid
   ```
   Example #2:
   ```yaml
   #pid_file: DATADIR/homeserver.pid
   ```
* Indentation matters! The indentation before a setting
  will determine whether a given setting is read as part of another
  setting, or considered on its own. Thus, in example #1, the `enabled` setting
  is read as a sub-option of the `presence` setting, and will be properly applied.

  However, the lack of indentation before the `enabled` setting in example #2 means
  that when reading the config, Synapse will consider both `presence` and `enabled` as
  different settings. In this case, `presence` has no value, and thus a default applied, and `enabled`
  is an option that Synapse doesn't recognize and thus ignores.

  Example #1:
  ```yaml
  presence:
    enabled: false
  ```
  Example #2:
  ```yaml
  presence:
  enabled: false
  ```
  In this manual, all top-level settings (ones with no indentation) are identified
  at the beginning of their section (i.e. "### `example_setting`") and
  the sub-options, if any, are identified and listed in the body of the section.
  In addition, each setting has an example of its usage, with the proper indentation
  shown.
---
## Modules

Server admins can expand Synapse's functionality with external modules.

See [here](../../modules/index.md) for more documentation on how to configure or create custom modules for Synapse.

---
### `modules`

*(array)* Use the `module` sub-option to add modules under this option to extend functionality. The `module` setting then has a sub-option, `config`, which can be used to define some configuration for the `module`. Defaults to `[]`.

Options for each entry include:

* `module` (string): Path to the Python class of the module.

* `config` (object): Configuration options for the module.

Example configuration:
```yaml
modules:
- module: my_super_module.MySuperClass
  config:
    do_thing: true
- module: my_other_super_module.SomeClass
  config: {}
```
---
## Server

Define your homeserver name and other base options.

---
### `server_name`

*(string)* This sets the public-facing domain of the server.

The `server_name` name will appear at the end of usernames and room addresses created on your server. For example if the `server_name` was example.com, usernames on your server would be in the format `@user:example.com`.

In most cases you should avoid using a matrix specific subdomain such as matrix.example.com or synapse.example.com as the `server_name` for the same reasons you wouldn't use user@email.example.com as your email address. See [here](../../delegate.md) for information on how to host Synapse on a subdomain while preserving a clean `server_name`.

The `server_name` cannot be changed later so it is important to configure this correctly before you start Synapse. It should be all lowercase and may contain an explicit port.

There is no default for this option.

Example configurations:
```yaml
server_name: matrix.org
```

```yaml
server_name: localhost:8080
```
---
### `pid_file`

*(string|null)* When running Synapse as a daemon, the file to store the pid in. Defaults to `null`.

Example configuration:
```yaml
pid_file: DATADIR/homeserver.pid
```
---
### `daemonize`

*(boolean)* Specifies whether Synapse should be started as a daemon process. If Synapse is being managed by [systemd](../../systemd-with-workers/), this option must be omitted or set to `false`.

This can also be set by the `--daemonize` (`-D`) argument when starting Synapse.

See `worker_daemonize` for more information on daemonizing workers.

Defaults to `false`.

Example configuration:
```yaml
daemonize: true
```
---
### `print_pidfile`

*(boolean)* Print the path to the pidfile just before daemonizing.

This can also be set by the `--print-pidfile` argument when starting Synapse.

Defaults to `false`.

Example configuration:
```yaml
print_pidfile: true
```
---
### `user_agent_suffix`

*(string|null)* A suffix that is appended to the Synapse user-agent (ex. `Synapse/v1.123.0`). Defaults to `null`.

Example configuration:
```yaml
user_agent_suffix: ' (I''m a teapot; Linux x86_64)'
```
---
### `use_frozen_dicts`

*(boolean)* Determines whether we should freeze the internal dict object in `FrozenEvent`. Freezing prevents bugs where we accidentally share e.g. signature dicts. However, freezing a dict is expensive.

> ⚠️ **Warning** – This option is known to introduce a new class of [comparison bugs](https://github.com/element-hq/synapse/issues/18117) in Synapse.

Defaults to `false`.

Example configuration:
```yaml
use_frozen_dicts: true
```
---
### `web_client_location`

*(string|null)* The absolute URL to the web client which `/` will redirect to. Defaults to `null`.

Example configuration:
```yaml
web_client_location: https://riot.example.com/
```
---
### `public_baseurl`

*(string|null)* The public-facing base URL that clients use to access this Homeserver (not including _matrix/...). This is the same URL a user might enter into the "Custom Homeserver URL" field on their client. If you use Synapse with a reverse proxy, this should be the URL to reach Synapse via the proxy. Otherwise, it should be the URL to reach Synapse's client HTTP listener (see [`listeners`](#listeners) below).

If unset or null, `https://<server_name>/` is used.

Defaults to `null`.

Example configuration:
```yaml
public_baseurl: https://example.com/
```
---
### `serve_server_wellknown`

*(boolean)* By default, other servers will try to reach our server on port 8448, which can be inconvenient in some environments.

Provided `https://<server_name>/` on port 443 is routed to Synapse, this option configures Synapse to serve a file at `https://<server_name>/.well-known/matrix/server`. This will tell other servers to send traffic to port 443 instead.

This option currently defaults to false.

See [Delegation of incoming federation traffic](../../delegate.md) for more information.

Defaults to `false`.

Example configuration:
```yaml
serve_server_wellknown: true
```
---
### `extra_well_known_client_content`

*(object)* This option allows server runners to add arbitrary key-value pairs to the [client-facing `.well-known` response](https://spec.matrix.org/latest/client-server-api/#well-known-uri). Note that the `public_baseurl` config option must be provided for Synapse to serve a response to `/.well-known/matrix/client` at all.

If this option is provided, it parses the given yaml to json and serves it on `/.well-known/matrix/client` endpoint alongside the standard properties.

*Added in Synapse 1.62.0.*

Example configuration:
```yaml
extra_well_known_client_content:
  option1: value1
  option2: value2
```
---
### `soft_file_limit`

*(integer)* Set the soft limit on the number of file descriptors synapse can use. Zero is used to indicate synapse should set the soft limit to the hard limit. Defaults to `0`.

Example configuration:
```yaml
soft_file_limit: 3
```
---
### `presence`

*(object)* Presence tracking allows users to see the state (e.g online/offline) of other local and remote users. This option replaces the previous top-level `use_presence` option.

This setting has the following sub-options:

* `enabled` (boolean|string): Set to false to disable presence tracking on this homeserver.

  Can also be set to a special value of "untracked" which ignores updates received via clients and federation, while still accepting updates from the [module API](../../modules/index.md).

  *The "untracked" option was added in Synapse 1.96.0.*

  Defaults to `true`.

* `include_offline_users_on_sync` (boolean): When clients perform an initial or `full_state` sync, presence results for offline users are not included by default. Setting `include_offline_users_on_sync` to `true` will always include offline users in the results. Defaults to `false`.

* `last_active_granularity` (duration): How long after a user was last active that they are still shown as "currently active" to other users. Larger values reduce the rate of presence updates sent to other users and servers.

  *Added in Synapse 1.156.0.*

  Defaults to `"1m"`.

* `sync_online_timeout` (duration): How long after a client's last sync request their presence is switched to offline. Clients are expected to keep a sync request open at (almost) all times while online, so this only needs to cover the gap between two consecutive sync requests. Note that if `rc_presence` is set to ratelimit how often syncs can affect presence, this must be greater than the ratelimit's interval or users will incorrectly be marked as offline in between syncs.

  *Added in Synapse 1.156.0.*

  Defaults to `"30s"`.

* `idle_timeout` (duration): How long after a user was last active that their presence is switched to "unavailable" (idle) while they remain connected. Must be greater than `last_active_granularity`.

  *Added in Synapse 1.156.0.*

  Defaults to `"5m"`.

Example configuration:
```yaml
presence:
  enabled: false
  include_offline_users_on_sync: false
```
---
### `require_auth_for_profile_requests`

*(boolean)* Whether to require authentication to retrieve profile data (avatars, display names) of other users through the client API. Note that profile data is also available via the federation API, unless `allow_profile_lookup_over_federation` is set to false. Defaults to `false`.

Example configuration:
```yaml
require_auth_for_profile_requests: true
```
---
### `limit_profile_requests_to_users_who_share_rooms`

*(boolean)* Use this option to require a user to share a room with another user in order to retrieve their profile information. Only checked on Client-Server requests. Profile requests from other servers should be checked by the requesting server. Defaults to `false`.

Example configuration:
```yaml
limit_profile_requests_to_users_who_share_rooms: true
```
---
### `include_profile_data_on_invite`

*(boolean)* Use this option to prevent a user's profile data from being retrieved and displayed in a room until they have joined it. By default, a user's profile data is included in an invite event, regardless of the values of the above two settings, and whether or not the users share a server. Defaults to `true`.

Example configuration:
```yaml
include_profile_data_on_invite: false
```
---
### `include_profile_updates_in_sync`

*(boolean)* Use this option to include updates of other users' profiles in sync responses, for users who share rooms.
Requires an [MSC4429](https://github.com/matrix-org/matrix-spec-proposals/pull/4429) compatible client, and is currently limited to legacy sync and local users only.
This feature is under development and should be used with caution on busy servers or servers which depend on `limit_profile_requests_to_users_who_share_rooms` for ensuring profile information doesn't leak across rooms. Defaults to `false`.

Example configuration:
```yaml
include_profile_updates_in_sync: true
```
---
### `allow_public_rooms_without_auth`

*(boolean)* If set to true, removes the need for authentication to access the server's public rooms directory through the client API, meaning that anyone can query the room directory. Defaults to `false`.

Example configuration:
```yaml
allow_public_rooms_without_auth: true
```
---
### `allow_public_rooms_over_federation`

*(boolean)* If set to true, allows any other homeserver to fetch the server's public rooms directory via federation. Defaults to `false`.

Example configuration:
```yaml
allow_public_rooms_over_federation: true
```
---
### `default_room_version`

*(string)* The default room version for newly created rooms on this server.

Known room versions are listed [here](https://spec.matrix.org/latest/rooms/#complete-list-of-room-versions)

For example, for room version 1, `default_room_version` should be set to "1".

_Changed in Synapse 1.76:_ the default version room version was increased from [9](https://spec.matrix.org/v1.5/rooms/v9/) to [10](https://spec.matrix.org/v1.5/rooms/v10/).
_Changed in Synapse 1.157:_ the default version room version was increased from [10](https://spec.matrix.org/v1.12/rooms/v10/) to [11](https://spec.matrix.org/v1.12/rooms/v11/).

Defaults to `"11"`.

Example configuration:
```yaml
default_room_version: '8'
```
---
### `gc_thresholds`

*(array|null)* The garbage collection threshold parameters to pass to `gc.set_threshold`, if defined. Defaults to `null`.

Example configuration:
```yaml
gc_thresholds:
- 700
- 10
- 10
```
---
### `gc_min_interval`

*(array)* The minimum time in seconds between each GC for a generation, regardless of the GC thresholds. This ensures that we don't do GC too frequently. A value of `[1s, 10s, 30s]` indicates that a second must pass between consecutive generation 0 GCs, etc.

Default configuration:
```yaml
gc_min_interval:
- 1s
- 10s
- 30s
```

Example configuration:
```yaml
gc_min_interval:
- 0.5s
- 30s
- 1m
```
---
### `filter_timeline_limit`

*(integer)* Set the limit on the returned events in the timeline in the get and sync operations. A value of -1 means no upper limit. Defaults to `100`.

Example configuration:
```yaml
filter_timeline_limit: 5000
```
---
### `block_non_admin_invites`

*(boolean)* Whether room invites to users on this server should be blocked (except those sent by local server admins). Defaults to `false`.

Example configuration:
```yaml
block_non_admin_invites: true
```
---
### `enable_search`

*(boolean)* If set to false, new messages will not be indexed for searching and users will receive errors when searching for messages. Defaults to `true`.

Example configuration:
```yaml
enable_search: false
```
---
### `ip_range_blacklist`

*(array)* This option prevents outgoing requests from being sent to the specified blacklisted IP address CIDR ranges. If this option is not specified then it defaults to private IP address ranges (see the example below).

The blacklist applies to the outbound requests for federation, identity servers, push servers, and for checking key validity for third-party invite events.

(0.0.0.0 and :: are always blacklisted, whether or not they are explicitly listed here, since they correspond to unroutable addresses.)

This option replaces `federation_ip_range_blacklist` in Synapse v1.25.0.

Note: The value is ignored when an HTTP proxy is in use.

Default configuration:
```yaml
ip_range_blacklist:
- 127.0.0.0/8
- 10.0.0.0/8
- 172.16.0.0/12
- 192.168.0.0/16
- 100.64.0.0/10
- 192.0.0.0/24
- 169.254.0.0/16
- 192.88.99.0/24
- 198.18.0.0/15
- 192.0.2.0/24
- 198.51.100.0/24
- 203.0.113.0/24
- 224.0.0.0/4
- ::1/128
- fe80::/10
- fc00::/7
- 2001:db8::/32
- ff00::/8
- fec0::/10
```
---
### `ip_range_whitelist`

*(array)* List of IP address CIDR ranges that should be allowed for federation, identity servers, push servers, and for checking key validity for third-party invite events. This is useful for specifying exceptions to wide-ranging blacklisted target IP ranges – e.g. for communication with a push server only visible in your network.

This whitelist overrides `ip_range_blacklist`.

Defaults to `[]`.

Example configuration:
```yaml
ip_range_whitelist:
- 192.168.1.1
```
---
### `listeners`

*(array)* List of ports that Synapse should listen on, their purpose and their configuration.

Valid resource names are:

* `client`: the client-server API (/_matrix/client). Also implies `media` and `static`. If configuring the main process, the Synapse Admin API (/_synapse/admin) is also implied.

* `consent`: user consent forms (/_matrix/consent). See [here](../../consent_tracking.md) for more.

* `federation`: the server-server API (/_matrix/federation). Also implies `media`, `keys`, `openid`

* `keys`: the key discovery API (/_matrix/key).

* `media`: the media API (/_matrix/media).

* `metrics`: the metrics interface. See [here](../../metrics-howto.md). (Not compatible with Unix sockets)

* `openid`: OpenID authentication. See [here](../../openid.md).

* `replication`: the HTTP replication API (/_synapse/replication). See [here](../../workers.md).

* `static`: static resources under synapse/static (/_matrix/static). (Mostly useful for "fallback authentication".)

* `health`: the [health check endpoint](../../reverse_proxy.md#health-check-endpoint). This endpoint is by default active for all other resources and does not have to be activated separately. This is only useful if you want to use the health endpoint explicitly on a dedicated port or for [workers](../../workers.md) and containers without listener e.g. [application services](../../workers.md#notifying-application-services).

Defaults to `[]`.

Options for each entry include:

* `port` (integer): The TCP port to bind to.

* `tag` (string|null): An alias for the port in the logger name. If set the tag is logged instead of the port. Default to `None`, is optional and only valid for listener with `type: http`. See the docs [request log format](../administration/request_log.md).

* `bind_addresses` (array|null): A list of local addresses to listen on. The default is "all local interfaces".

* `type` (string): The type of listener. Normally `http`, but other valid options are [`manhole`](../../manhole.md) and [`metrics`](../../metrics-howto.md).

* `tls` (boolean): Set to true to enable TLS for this listener. Will use the TLS key/cert specified in tls_private_key_path/tls_certificate_path.

* `x_forwarded` (boolean): Only valid for an `http` listener. Set to true to use the X-Forwarded-For header as the client IP. Useful when Synapse is behind a [reverse-proxy](../../reverse_proxy.md).

* `request_id_header` (string|null): The header extracted from each incoming request that is used as the basis for the request ID. The request ID is used in [logs](../administration/request_log.md#request-log-format) and tracing to correlate and match up requests. When unset, Synapse will automatically generate sequential request IDs. This option is useful when Synapse is behind a [reverse-proxy](../../reverse_proxy.md).

  _Added in Synapse 1.68.0._

* `resources` (array): Only valid for an `http` listener. A list of resources to host on this port.

  Options for each entry include:

  * `names` (array): A list of names of HTTP resources. See below for a list of valid resource names.

  * `compress` (boolean): Set to true to enable gzip compression on HTTP bodies for this resource. This is currently only supported with the `client`, `consent`, `metrics` and `federation` resources.

* `additional_resources` (object): Only valid for an `http` listener. A map of additional endpoints which should be loaded via dynamic modules.

* `path` (string): A path and filename for a Unix socket. Make sure it is located in a directory with read and write permissions, and that it already exists (the directory will not be created). Defaults to `None`.
  * **Note**: The use of both `path` and `port` options for the same `listener` is not compatible.
  * The `x_forwarded` option defaults to true  when using Unix sockets and can be omitted.
  * Other options that would not make sense to use with a UNIX socket, such as `bind_addresses` and `tls` will be ignored and can be removed.

  _Added in Synapse 1.89.0_: Unix socket support

* `mode` (integer|null): The file permissions to set on the UNIX socket. Defaults to `666` if unset or null.

  **Note:** Must be set as `type: http` (does not support `metrics` and `manhole`). Also make sure that `metrics` is not included in `resources` -> `names`

  _Added in Synapse 1.89.0_: Unix socket support

Example configurations:
```yaml
listeners:
- port: 8448
  type: http
  tls: true
  resources:
  - names:
    - client
    - federation
```

```yaml
listeners:
- port: 8008
  tls: false
  type: http
  x_forwarded: true
  bind_addresses:
  - ::1
  - 127.0.0.1
  resources:
  - names:
    - client
    - federation
    compress: false
  additional_resources:
    /_matrix/my/custom/endpoint:
      module: my_module.CustomRequestHandler
      config: {}
- port: 9000
  bind_addresses:
  - ::1
  - 127.0.0.1
  type: manhole
```

```yaml
listeners:
- path: /run/synapse/main_public.sock
  type: http
  resources:
  - names:
    - client
    - federation
```
---
### `manhole`

*(integer|null)* Turn on the Twisted telnet manhole service on the given port.

This can also be set by the `--manhole` argument when starting Synapse.

Defaults to `null`.

Example configuration:
```yaml
manhole: 1234
```
---
### `manhole_settings`

*(object)* Connection settings for the manhole. You can find more information on the manhole [here](../../manhole.md).

This setting has the following sub-options:

* `username` (string|null): The username for the manhole. This defaults to "matrix".

* `password` (string|null): The password for the manhole. This defaults to "rabbithole".

* `ssh_priv_key_path` (string|null): The private SSH key used to encrypt the manhole traffic. If left unset, then hardcoded and non-secret keys are used, which could allow traffic to be intercepted if sent over a public network.

* `ssh_pub_key_path` (string|null): The public SSH key corresponsing to `ssh_priv_key_path`. If left unset, a hardcoded key is used.

Example configuration:
```yaml
manhole_settings:
  username: manhole
  password: mypassword
  ssh_priv_key_path: CONFDIR/id_rsa
  ssh_pub_key_path: CONFDIR/id_rsa.pub
```
---
### `http_proxy`

*(string|null)* Proxy server to use for HTTP requests.
For more details, see the [forward proxy documentation](../../setup/forward_proxy.md). There is no default for this option.

Example configuration:
```yaml
http_proxy: http://USERNAME:PASSWORD@10.0.1.1:8080/
```
---
### `https_proxy`

*(string|null)* Proxy server to use for HTTPS requests.
For more details, see the [forward proxy documentation](../../setup/forward_proxy.md). There is no default for this option.

Example configuration:
```yaml
https_proxy: http://USERNAME:PASSWORD@proxy.example.com:8080/
```
---
### `no_proxy_hosts`

*(array)* List of hosts, IP addresses, or IP ranges in CIDR format which should not use the proxy. Synapse will directly connect to these hosts.
For more details, see the [forward proxy documentation](../../setup/forward_proxy.md). There is no default for this option.

Example configuration:
```yaml
no_proxy_hosts:
- master.hostname.example.com
- 10.1.0.0/16
- 172.30.0.0/16
```
---
### `matrix_authentication_service`

*(object)* The `matrix_authentication_service` setting configures integration with [Matrix Authentication Service (MAS)](https://github.com/element-hq/matrix-authentication-service).

This setting has the following sub-options:

* `enabled` (boolean): Whether or not to enable the MAS integration. If this is set to `false`, Synapse will use its legacy internal authentication API. Defaults to `false`.

* `endpoint` (string): The URL where Synapse can reach MAS. This *must* have the `discovery` and `oauth` resources mounted. Defaults to `"http://localhost:8080"`.

* `force_http2` (boolean): Force HTTP/2 over plaintext (H2C) when connecting to MAS. MAS supports this natively, but a reverse proxy between Synapse and MAS may not. Defaults to `false`.

* `secret` (string|null): A shared secret that will be used to authenticate requests from and to MAS.

* `secret_path` (string|null): Alternative to `secret`, reading the shared secret from a file. The file should be a plain text file, containing only the secret. Synapse reads the secret from the given file once at startup.

Example configuration:
```yaml
matrix_authentication_service:
  enabled: true
  secret: someverysecuresecret
  endpoint: http://localhost:8080
```
---
### `dummy_events_threshold`

*(integer)* Forward extremities can build up in a room due to networking delays between homeservers. Once this happens in a large room, calculation of the state of that room can become quite expensive. To mitigate this, once the number of forward extremities reaches a given threshold, Synapse will send an `org.matrix.dummy_event` event, which will reduce the forward extremities in the room.

This setting defines the threshold (i.e. number of forward extremities in the room) at which dummy events are sent.

Defaults to `10`.

Example configuration:
```yaml
dummy_events_threshold: 5
```
---
### `delete_stale_devices_after`

An optional duration. If set, Synapse will run a daily background task to log out and delete any device that hasn't been accessed for more than the specified amount of time.

A value of null means devices are never pruned.

**Note:** This task will always run on the main process, regardless of the value of `run_background_tasks_on`. This is due to workers currently not having the ability to delete devices.

Defaults to `null`.

Example configuration:
```yaml
delete_stale_devices_after: 1y
```
---
### `email`

*(object)* Configuration for sending emails from Synapse.

Server admins can configure custom templates for email content. See [here](../../templates.md) for more information.

This setting has the following sub-options:

* `smtp_host` (string): The hostname of the outgoing SMTP server to use. Defaults to `"localhost"`.

* `smtp_port` (string|null): The port on the mail server for outgoing SMTP. If null or unset, 465 is used if `force_tls` is true, else 25.

  _Changed in Synapse 1.64.0:_ the default port is now aware of `force_tls`.

  Defaults to `null`.

* `smtp_user` (string|null): Username for authentication to the SMTP server. Defaults to `null`.

* `smtp_pass` (string|null): Password for authentication to the SMTP server. Defaults to `null`.

* `force_tls` (boolean): By default, Synapse connects over plain text and then optionally upgrades to TLS via STARTTLS. If this option is set to true, TLS is used from the start (Implicit TLS), and the option `require_transport_security` is ignored. It is recommended to enable this if supported by your mail server.

  _New in Synapse 1.64.0._

  Defaults to `false`.

* `require_transport_security` (boolean): Set to true to require TLS transport security for SMTP. By default, Synapse will connect over plain text, and will then switch to TLS via STARTTLS *if the SMTP server supports it*. If this option is set, Synapse will refuse to connect unless the server supports STARTTLS. Defaults to `false`.

* `enable_tls` (boolean): By default, if the server supports TLS, it will be used, and the server must present a certificate that is valid for `tlsname`. If this option is set to false, TLS will not be used. Defaults to `true`.

* `tlsname` (string): The domain name the SMTP server's TLS certificate must be valid for, defaulting to `smtp_host`.

* `notif_from` (string|null): Defines the "From" address to use when sending emails. It must be set if email sending is enabled. The placeholder `%(app)s` will be replaced by the application name, which is normally set in `app_name`, but may be overridden by the Matrix client application. Note that the placeholder must be written `%(app)s`, including the trailing 's'. Defaults to `null`.

* `app_name` (string): Defines the default value for `%(app)s` in `notif_from` and email subjects. Defaults to `"Matrix"`.

* `enable_notifs` (boolean): Set to true to allow users to receive e-mail notifications. If this is not set, users can configure e-mail notifications but will not receive them. Defaults to `false`.

* `notif_for_new_users` (boolean): Set to false to disable automatic subscription to email notifications for new users. Defaults to `true`.

* `notif_delay_before_mail` (duration): The time to wait before emailing about a notification. This gives the user a chance to view the message via push or an open client.

  _New in Synapse 1.99.0._

  Defaults to `"10m"`.

* `client_base_url` (string): Custom URL for client links within the email notifications. (This setting used to be called `riot_base_url`; the old name is still supported for backwards-compatibility but is now deprecated.) Defaults to `"https://matrix.to"`.

* `validation_token_lifetime` (duration): Configures the time that a validation email will expire after sending. Defaults to `"1h"`.

* `invite_client_location` (string|null): The web client location to direct users to during an invite. This is passed to the identity server as the `org.matrix.web_client_location` key. If null or unset no guidance is given to the identity server. Defaults to `null`.

* `subjects` (object): Subjects to use when sending emails from Synapse. The placeholder `%(app)s` will be replaced with the value of the `app_name` setting, or by a value dictated by the Matrix client application. In addition, each subject can use the following placeholders: `%(person)s`, which will be replaced by the displayname of the user(s) that sent the message(s), e.g. "Alice and Bob", and `%(room)s`, which will be replaced by the name of the room the message(s) have been sent to, e.g. "My super room". In addition, emails related to account administration will can use the `%(server_name)s` placeholder, which will be replaced by the value of the `server_name` setting in your Synapse configuration.

  This setting has the following sub-options:

  * `message_from_person_in_room` (string): Subject to use to notify about one message from one or more user(s) in a room which has a name. Defaults to `"[%(app)s] You have a message on %(app)s from %(person)s in the %(room)s room..."`.

  * `message_from_person` (string): Subject to use to notify about one message from one or more user(s) in a room which doesn't have a name. Defaults to `"[%(app)s] You have a message on %(app)s from %(person)s..."`.

  * `messages_from_person` (string): Subject to use to notify about multiple messages from one or more users in a room which doesn't have a name. Defaults to `"[%(app)s] You have messages on %(app)s from %(person)s..."`.

  * `messages_in_room` (string): Subject to use to notify about multiple messages in a room which has a name. Defaults to `"[%(app)s] You have messages on %(app)s in the %(room)s room..."`.

  * `messages_in_room_and_others` (string): Subject to use to notify about multiple messages in multiple rooms. Defaults to `"[%(app)s] You have messages on %(app)s in the %(room)s room and others..."`.

  * `messages_from_person_and_others` (string): Subject to use to notify about multiple messages from multiple persons in multiple rooms. This is similar to the setting above except it's used when the room in which the notification was triggered has no name. Defaults to `"[%(app)s] You have messages on %(app)s from %(person)s and others..."`.

  * `invite_from_person_to_room` (string): Subject to use to notify about an invite to a room which has a name. Defaults to `"[%(app)s] %(person)s has invited you to join the %(room)s room on %(app)s..."`.

  * `invite_from_person` (string): Subject to use to notify about an invite to a room which doesn't have a name. Defaults to `"[%(app)s] %(person)s has invited you to chat on %(app)s..."`.

  * `password_reset` (string): Subject to use when sending a password reset email. Defaults to `"[%(server_name)s] Password reset"`.

  * `email_validation` (string): Subject to use when sending a verification email to assert an address's ownership. Defaults to `"[%(server_name)s] Validate your email"`.

Example configuration:
```yaml
email:
  smtp_host: mail.server
  smtp_port: 587
  smtp_user: exampleusername
  smtp_pass: examplepassword
  force_tls: true
  require_transport_security: true
  enable_tls: false
  tlsname: mail.server.example.com
  notif_from: Your Friendly %(app)s homeserver <noreply@example.com>
  app_name: my_branded_matrix_server
  enable_notifs: true
  notif_for_new_users: false
  client_base_url: http://localhost/riot
  validation_token_lifetime: 15m
  invite_client_location: https://app.element.io
  subjects:
    message_from_person_in_room: '[%(app)s] You have a message on %(app)s from %(person)s
      in the %(room)s room...'
    message_from_person: '[%(app)s] You have a message on %(app)s from %(person)s...'
    messages_from_person: '[%(app)s] You have messages on %(app)s from %(person)s...'
    messages_in_room: '[%(app)s] You have messages on %(app)s in the %(room)s room...'
    messages_in_room_and_others: '[%(app)s] You have messages on %(app)s in the %(room)s
      room and others...'
    messages_from_person_and_others: '[%(app)s] You have messages on %(app)s from
      %(person)s and others...'
    invite_from_person_to_room: '[%(app)s] %(person)s has invited you to join the
      %(room)s room on %(app)s...'
    invite_from_person: '[%(app)s] %(person)s has invited you to chat on %(app)s...'
    password_reset: '[%(server_name)s] Password reset'
    email_validation: '[%(server_name)s] Validate your email'
```
---
### `max_event_delay_duration`

The maximum allowed duration by which sent events can be delayed, as per [MSC4140](https://github.com/matrix-org/matrix-spec-proposals/pull/4140). Must be a positive value if set.

If null or unset, sending of delayed events is disallowed.

Defaults to `null`.

Example configuration:
```yaml
max_event_delay_duration: 24h
```
---
### `user_types`

*(object)* Configuration settings related to the user types feature.

This setting has the following sub-options:

* `default_user_type` (string|null): The default user type to use for registering new users when no value has been specified. Defaults to none. Defaults to `null`.

* `extra_user_types` (array): Array of additional user types to allow. These are treated as real users. Defaults to `[]`.

Example configuration:
```yaml
user_types:
  default_user_type: custom
  extra_user_types:
  - custom
  - custom2
```
---
## Homeserver blocking

Useful options for Synapse admins.

---
### `admin_contact`

*(string|null)* How to reach the server admin, used in `ResourceLimitError`. Defaults to `null`.

Example configuration:
```yaml
admin_contact: mailto:admin@server.com
```
---
### `hs_disabled`

*(boolean)* Blocks users from connecting to the homeserver and provides the human-readable reason given in `hs_disabled_message`. Defaults to `false`.

Example configuration:
```yaml
hs_disabled: true
```
---
### `hs_disabled_message`

*(string)* Human-readable reason why the connection was blocked. Defaults to `"Homeserver is currently blocked"`.

Example configuration:
```yaml
hs_disabled_message: Reason for why the HS is blocked
```
---
### `limit_usage_by_mau`

*(boolean)* This option disables/enables monthly active user blocking. Used in cases where the admin or server owner wants to limit to the number of monthly active users. When enabled and a limit is reached the server returns a `ResourceLimitError` with error type `Codes.RESOURCE_LIMIT_EXCEEDED`. If this is enabled, a value for `max_mau_value` must also be set.

See [Monthly Active Users](../administration/monthly_active_users.md) for details on how to configure MAU.

Defaults to `false`.

Example configuration:
```yaml
limit_usage_by_mau: true
```
---
### `max_mau_value`

*(integer)* This option sets the hard limit of monthly active users above which the server will start blocking user actions if `limit_usage_by_mau` is enabled. Defaults to `0`.

Example configuration:
```yaml
max_mau_value: 50
```
---
### `mau_trial_days`

*(integer)* The option `mau_trial_days` is a means to add a grace period for active users. It means that users must be active for the specified number of days before they can be considered active and guards against the case where lots of users sign up in a short space of time never to return after their initial session. Defaults to `0`.

Example configuration:
```yaml
mau_trial_days: 5
```
---
### `mau_appservice_trial_days`

*(object)* The option `mau_appservice_trial_days` is similar to `mau_trial_days`, but applies a different trial number if the user was registered by an appservice. A value of 0 means no trial days are applied. Appservices not listed in this dictionary use the value of `mau_trial_days` instead. Defaults to `{}`.

Example configuration:
```yaml
mau_appservice_trial_days:
  my_appservice_id: 3
  another_appservice_id: 6
```
---
### `mau_limit_alerting`

*(boolean)* Limit client-side alerting should the mau limit be reached. This is useful for small instances where the admin has 5 mau seats (say) for 5 specific people and no interest increasing the mau limit further. Defaults to `true`.

Example configuration:
```yaml
mau_limit_alerting: false
```
---
### `mau_stats_only`

*(boolean)* If enabled, the metrics for the number of monthly active users will be populated, however no one will be limited based on these numbers. If `limit_usage_by_mau` is true, this is implied to be true. Defaults to `false`.

Example configuration:
```yaml
mau_stats_only: true
```
---
### `mau_limit_reserved_threepids`

*(array)* Sometimes the server admin will want to ensure certain accounts are never blocked by mau checking. These accounts are specified by this option. Add accounts by specifying the `medium` and `address` of the reserved threepid (3rd party identifier). Defaults to `[]`.

Options for each entry include:

* `medium` (string): Medium of the account threepid.

* `address` (string): Address of the account threepid.

Example configuration:
```yaml
mau_limit_reserved_threepids:
- medium: email
  address: reserved_user@example.com
```
---
### `server_context`

*(string|null)* This option is used by phonehome stats to group together related servers. Defaults to `null`.

Example configuration:
```yaml
server_context: context
```
---
### `limit_remote_rooms`

*(object)* When this option is enabled, the room "complexity" will be checked before a user joins a new remote room. If it is above the complexity limit, the server will disallow joining, or will instantly leave. This is useful for homeservers that are resource-constrained. In Synapse, the complexity of a room is measured by the number of current state events in a room, divided by 500. "Current" here means the latest state, i.e. if a user joins, then leaves, then joins, that will count as 1 current `m.room.member` state event.

This setting has the following sub-options:

* `enabled` (boolean): Whether this check is enabled. Defaults to `false`.

* `complexity` (number): The limit above which rooms cannot be joined. Defaults to `1.0`.

* `complexity_error` (string): Override the error which is returned when the room is too complex with a custom message. Defaults to `"Your homeserver is unable to join rooms this large or complex. Please speak to your server administrator, or upgrade your instance to join this room."`.

* `admins_can_join` (boolean): Allow server admins to join complex rooms. Defaults to `false`.

Example configuration:
```yaml
limit_remote_rooms:
  enabled: true
  complexity: 0.5
  complexity_error: I can't let you do that, Dave.
  admins_can_join: true
```
---
### `require_membership_for_aliases`

*(boolean)* Whether to require a user to be in the room to add an alias to it. Defaults to `true`.

Example configuration:
```yaml
require_membership_for_aliases: false
```
---
### `allow_per_room_profiles`

*(boolean)* Whether to allow per-room membership profiles through the sending of membership events with profile information that differs from the target's global profile. Defaults to `true`.

Example configuration:
```yaml
allow_per_room_profiles: false
```
---
### `max_avatar_size`

The largest permissible file size in bytes for a user avatar. Defaults to no restriction. Use M for MB and K for KB.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Defaults to `null`.

Example configuration:
```yaml
max_avatar_size: 10M
```
---
### `allowed_avatar_mimetypes`

*(array|null)* The MIME types allowed for user avatars. Defaults to no restriction.

Note that user avatar changes will not work if this is set without using Synapse's media repository.

Defaults to `null`.

Example configuration:
```yaml
allowed_avatar_mimetypes:
- image/png
- image/jpeg
- image/gif
```
---
### `redaction_retention_period`

How long to keep redacted events in unredacted form in the database. After this period redacted events get replaced with their redacted form in the DB.

Synapse will check whether the rentention period has concluded for redacted events every 5 minutes. Thus, even if this option is set to `0`, Synapse may still take up to 5 minutes to purge redacted events from the database. Set to `null` to disable.

Defaults to `"7d"`.

Example configuration:
```yaml
redaction_retention_period: 28d
```
---
### `forgotten_room_retention_period`

How long to keep locally forgotten rooms before purging them from the DB. A value of `null` means it's disabled. Defaults to `null`.

Example configuration:
```yaml
forgotten_room_retention_period: 28d
```
---
### `user_ips_max_age`

How long to track users' last seen time and IPs in the database. Set to `null` to disable clearing out of old rows. Defaults to `"28d"`.

Example configuration:
```yaml
user_ips_max_age: 14d
```
---
### `request_token_inhibit_3pid_errors`

*(boolean)* Inhibits the `/requestToken` endpoints from returning an error that might leak information about whether an e-mail address is in use or not on this homeserver. Note that for some endpoints the error situation is the e-mail already being used, and for others the error is entering the e-mail being unused. If this option is enabled, instead of returning an error, these endpoints will act as if no error happened and return a fake session ID (`sid`) to clients. Defaults to `false`.

Example configuration:
```yaml
request_token_inhibit_3pid_errors: true
```
---
### `next_link_domain_whitelist`

*(array|null)* A list of domains that the domain portion of `next_link` parameters must match.

This parameter is optionally provided by clients while requesting validation of an email or phone number, and maps to a link that users will be automatically redirected to after validation succeeds. Clients can make use this parameter to aid the validation process.

The whitelist is applied whether the homeserver or an identity server is handling validation.

The default value is no whitelist functionality; all domains are allowed. Setting this value to an empty list will instead disallow all domains.

Defaults to `null`.

Example configuration:
```yaml
next_link_domain_whitelist: matrix.org
```
---
### `templates`

*(object)* These options define templates to use when generating email or HTML page contents.

See [here](../../templates.md) for more information about using custom templates.

This setting has the following sub-options:

* `custom_template_directory` (string|null): Determines which directory Synapse will try to find template files in to use to generate email or HTML page contents. If not set, or a file is not found within the template directory, a default template from within the Synapse package will be used. Defaults to `null`.

Example configuration:
```yaml
templates:
  custom_template_directory: /path/to/custom/templates/
```
---
### `retention`

*(object)* This option and the associated options determine message retention policy at the server level.

Room admins and mods can define a retention period for their rooms using the `m.room.retention` state event, and server admins can cap this period by setting the `allowed_lifetime_min` and `allowed_lifetime_max` config options.

If this feature is enabled, Synapse will regularly look for and purge events which are older than the room's maximum retention period. Synapse will also filter events received over federation so that events that should have been purged are ignored and not stored again.

The message retention policies feature is disabled by default. You can read more about this feature [here](../../message_retention_policies.md).

This setting has the following sub-options:

* `enabled` (boolean): Enforce message retention policies Defaults to `false`.

* `default_policy` (object): Default message retention policy. If set, Synapse will apply it to rooms that lack the `m.room.retention` state event.

  This setting has the following sub-options:

  * `min_lifetime`: Minimum message retention time of the default message retention policy. Synapse doesn't take this option into account yet. Defaults to `null`.

  * `max_lifetime`: Maximum message retention time of the default message retention policy. Defaults to `null`.

* `allowed_lifetime_min`: Retention policy limit. If set, and the state of a room contains a `m.room.retention` event in its state which contains a `min_lifetime` that's beyond this bound, Synapse will cap the room's policy to these limits when running purge jobs. Defaults to `null`.

* `allowed_lifetime_max`: Retention policy limit. If set, and the state of a room contains a `m.room.retention` event in its state which contains a `max_lifetime` that's beyond this bound, Synapse will cap the room's policy to these limits when running purge jobs. Defaults to `null`.

* `purge_jobs` (array|null): Server admins can define the settings of the background jobs purging the events whose lifetime has expired under the `purge_jobs` section.

  If no configuration is provided for this option, a single job will be set up to delete expired events in every room daily.

  Each job's configuration defines which range of message lifetimes the job takes care of. For example, if `shortest_max_lifetime` is "2d" and `longest_max_lifetime` is "3d", the job will handle purging expired events in rooms whose state defines a `max_lifetime` that's both higher than 2 days, and lower than or equal to 3 days. Both the minimum and the maximum value of a range are optional, e.g. a job with no `shortest_max_lifetime` and a `longest_max_lifetime` of "3d" will handle every room with a retention policy whose `max_lifetime` is lower than or equal to three days.

  The rationale for this per-job configuration is that some rooms might have a retention policy with a low `max_lifetime`, where history needs to be purged of outdated messages on a more frequent basis than for the rest of the rooms (e.g. every 12h), but not want that purge to be performed by a job that's iterating over every room it knows, which could be heavy on the server.

  If any purge job is configured, it is strongly recommended to have at least a single job with neither `shortest_max_lifetime` nor `longest_max_lifetime` set, or one job without `shortest_max_lifetime` and one job without `longest_max_lifetime` set. Otherwise some rooms might be ignored, even if `allowed_lifetime_min` and `allowed_lifetime_max` are set, because capping a room's policy to these values is done after the policies are retrieved from Synapse's database (which is done using the range specified in a purge job's configuration).

  Defaults to `null`.

  Options for each entry include:

  * `shortest_max_lifetime`: Apply job to rooms that have a `max_lifetime` higher than `shortest_max_lifetime`. A value of `null` never excludes any room.

  * `longest_max_lifetime`: Apply job to rooms that have a `max_lifetime` lower than or equal to `shortest_max_lifetime`. A value of `null` never excludes any room.

  * `interval` (duration): How often to run the job.

Example configuration:
```yaml
retention:
  enabled: true
  default_policy:
    min_lifetime: 1d
    max_lifetime: 1y
  allowed_lifetime_min: 1d
  allowed_lifetime_max: 1y
  purge_jobs:
  - longest_max_lifetime: 3d
    interval: 12h
  - shortest_max_lifetime: 3d
    interval: 1d
```
---
## TLS

Options related to TLS.

---
### `tls_certificate_path`

*(string|null)* This option specifies a PEM-encoded X509 certificate for TLS. This certificate, as of Synapse 1.0, will need to be a valid and verifiable certificate, signed by a recognised Certificate Authority.

Be sure to use a `.pem` file that includes the full certificate chain including any intermediate certificates (for instance, if using certbot, use `fullchain.pem` as your certificate, not `cert.pem`).

Defaults to `null`.

Example configuration:
```yaml
tls_certificate_path: CONFDIR/SERVERNAME.tls.crt
```
---
### `tls_private_key_path`

*(string|null)* PEM-encoded private key for TLS. Defaults to `null`.

Example configuration:
```yaml
tls_private_key_path: CONFDIR/SERVERNAME.tls.key
```
---
### `federation_verify_certificates`

*(boolean)* Whether to verify TLS server certificates for outbound federation requests. To disable certificate verification, set the option to false. Defaults to `true`.

Example configuration:
```yaml
federation_verify_certificates: false
```
---
### `federation_client_minimum_tls_version`

*(string)* The minimum TLS version that will be used for outbound federation requests.

Configurable to `"1"`, `"1.1"`, `"1.2"`, or `"1.3"`. Note that setting this value higher than `"1.2"` will prevent federation to most of the public Matrix network: only configure it to `"1.3"` if you have an entirely private federation setup and you can ensure TLS 1.3 support.

Defaults to `"1"`.

Example configuration:
```yaml
federation_client_minimum_tls_version: '1.2'
```
---
### `federation_certificate_verification_whitelist`

*(array)* Skip federation certificate verification on a given whitelist of domains.

This setting should only be used in very specific cases, such as federation over Tor hidden services and similar. For private networks of homeservers, you likely want to use a private CA instead.

Only effective if `federation_verify_certificates` is `true`.

Defaults to `[]`.

Example configuration:
```yaml
federation_certificate_verification_whitelist:
- lon.example.com
- '*.domain.com'
- '*.onion'
```
---
### `federation_custom_ca_list`

*(array)* List of custom certificate authorities for federation traffic.

This setting should only normally be used within a private network of homeservers.

Note that this list will replace those that are provided by your operating environment. Certificates must be in PEM format.

Defaults to `[]`.

Example configuration:
```yaml
federation_custom_ca_list:
- myCA1.pem
- myCA2.pem
- myCA3.pem
```
---
## Federation

Options related to federation.

---
### `federation_domain_whitelist`

*(array)* Restrict federation to the given whitelist of domains. N.B. we recommend also firewalling your federation listener to limit inbound federation traffic as early as possible, rather than relying purely on this application-layer restriction.
If specified as an empty list (`[]`), federation will be denied with all servers. Specifying an empty list (`[]`) here is the recommended way of disabling federation.
If not specified, the default is to allow federation with all servers.
Note: this does not stop a server from joining rooms that servers not on the whitelist are in. As such, this option is really only useful to establish a "private federation", where a group of servers all whitelist each other and have the same whitelist. There is no default for this option.

Example configuration:
```yaml
federation_domain_whitelist:
- lon.example.com
- nyc.example.com
- syd.example.com
```
---
### `federation_whitelist_endpoint_enabled`

*(boolean)* Enables an endpoint for fetching the federation whitelist config.

The request method and path is `GET /_synapse/client/v1/config/federation_whitelist`, and the response format is:

```json
{
    "whitelist_enabled": true,  // Whether the federation whitelist is being enforced
    "whitelist": [  // Which server names are allowed by the whitelist
        "example.com"
    ]
}
```

If `whitelist_enabled` is `false` then the server is permitted to federate with all others.

The endpoint requires authentication.

Defaults to `false`.

Example configuration:
```yaml
federation_whitelist_endpoint_enabled: true
```
---
### `federation_metrics_domains`

*(array)* Report prometheus metrics on the age of PDUs being sent to and received from the given domains. This can be used to give an idea of "delay" on inbound and outbound federation, though be aware that any delay can be due to problems at either end or with the intermediate network. Defaults to `[]`.

Example configuration:
```yaml
federation_metrics_domains:
- matrix.org
- example.com
```
---
### `allow_profile_lookup_over_federation`

*(boolean)* Set to false to disable profile lookup over federation. By default, the Federation API allows other homeservers to obtain profile data of any user on this homeserver. Defaults to `true`.

Example configuration:
```yaml
allow_profile_lookup_over_federation: false
```
---
### `allow_device_name_lookup_over_federation`

*(boolean)* Set this option to true to allow device display name lookup over federation. By default, the Federation API prevents other homeservers from obtaining the display names of any user devices on this homeserver. Defaults to `false`.

Example configuration:
```yaml
allow_device_name_lookup_over_federation: true
```
---
### `federation`

*(object)* The federation section defines some sub-options related to federation.

The following options are related to configuring timeout and retry logic for one request, independently of the others. Short retry algorithm is used when something or someone will wait for the request to have an answer, while long retry is used for requests that happen in the background, like sending a federation transaction.

`destination_*` options control the retry logic when communicating with a specific homeserver destination. Unlike the previous configuration options, these values apply across all requests for a given destination and the state of the backoff is stored in the database.

This setting has the following sub-options:

* `client_timeout` (duration): Timeout for the federation requests. Defaults to `"60s"`.

* `max_short_retry_delay` (duration): Maximum delay to be used for the short retry algo. Defaults to `"2s"`.

* `max_long_retry_delay` (duration): Maximum delay to be used for the long retry algo. Defaults to `"60s"`.

* `max_short_retries` (integer): Maximum number of retries for the short retry algo. Defaults to `3`.

* `max_long_retries` (integer): Maximum number of retries for the long retry algo. Defaults to `10`.

* `destination_min_retry_interval` (duration): The initial backoff, after the first request fails. Defaults to `"10m"`.

* `destination_retry_multiplier` (integer): How much we multiply the backoff by after each subsequent fail. Defaults to `2`.

* `destination_max_retry_interval` (duration): A cap on the backoff. Defaults to `"1w"`.

Example configuration:
```yaml
federation:
  client_timeout: 180s
  max_short_retry_delay: 7s
  max_long_retry_delay: 100s
  max_short_retries: 5
  max_long_retries: 20
  destination_min_retry_interval: 30s
  destination_retry_multiplier: 5
  destination_max_retry_interval: 12h
```
---
## Caching

Options related to caching.

---
### `event_cache_size`

*(size)* The number of events to cache in memory. Defaults to 10K. Like other caches, this is affected by `caches.global_factor` (see below).

For example, the default is 10K and the global_factor default is 0.5.

Since 10K * 0.5 is 5K then the event cache size will be 5K.

The cache affected by this configuration is named as "\*getEvent\*".

Note that this option is not part of the `caches` section.

Defaults to `"10K"`.

Example configuration:
```yaml
event_cache_size: 15K
```
---
### `caches`

*(object)* A cache "factor" is a multiplier that can be applied to each of Synapse's caches in order to increase or decrease the maximum number of entries that can be stored.

This setting has the following sub-options:

* `global_factor` (number): Controls the global cache factor, which is the default cache factor for all caches if a specific factor for that cache is not otherwise set.

  This can also be set by the `SYNAPSE_CACHE_FACTOR` environment variable. Setting by environment variable takes priority over setting through the config file.

  Defaults to 0.5, which will halve the size of all caches.

  Note that changing this value also affects the HTTP connection pool.

  Defaults to `0.5`.

* `per_cache_factors` (object): A dictionary of cache name to cache factor for that individual cache. Overrides the global cache factor for a given cache.

  These can also be set through environment variables comprised of `SYNAPSE_CACHE_FACTOR_` + the name of the cache in capital letters and underscores. Setting by environment variable takes priority over setting through the config file. Ex. `SYNAPSE_CACHE_FACTOR_GET_USERS_WHO_SHARE_ROOM_WITH_USER=2.0`

  Some caches have '*' and other characters that are not alphanumeric or underscores. These caches can be named with or without the special characters stripped. For example, to specify the cache factor for `*stateGroupCache*` via an environment variable would be `SYNAPSE_CACHE_FACTOR_STATEGROUPCACHE=2.0`.

  Defaults to `{}`.

* `expire_caches` (boolean): Controls whether cache entries are evicted after a specified time period. Set to false to disable this feature. Note that never expiring caches may result in excessive memory usage. Defaults to `true`.

* `cache_entry_ttl` (duration): If `expire_caches` is enabled, this flag controls how long an entry can be in a cache without having been accessed before being evicted. Defaults to `"30m"`.

* `sync_response_cache_duration` (duration): Controls how long the results of a /sync request are cached for after a successful response is returned. A higher duration can help clients with intermittent connections, at the cost of higher memory usage. A value of zero means that sync responses are not cached.

  *Changed in Synapse 1.62.0*: The default was changed from 0 to 2m.

  Defaults to `"2m"`.

* `cache_autotuning` (object): `cache_autotuning` and its sub-options `max_cache_memory_usage`, `target_cache_memory_usage`, and `min_cache_ttl` work in conjunction with each other to maintain a balance between cache memory usage and cache entry availability. You must be using [jemalloc](../administration/admin_faq.md#help-synapse-is-slow-and-eats-all-my-ramcpu) to utilize this option, and all three of the options must be specified for this feature to work. This option defaults to off, enable it by providing values for the sub-options listed below. Please note that the feature will not work and may cause unstable behavior (such as excessive emptying of caches or exceptions) if all of the values are not provided. Please see the [Config Conventions](#config-conventions) for information on how to specify memory size and cache expiry durations.

  This setting has the following sub-options:

  * `max_cache_memory_usage`: Sets a ceiling on how much memory the cache can use before caches begin to be continuously evicted. They will continue to be evicted until the memory usage drops below the `target_cache_memory_usage`, set in the setting below, or until the `min_cache_ttl` is hit. Defaults to `null`.

  * `target_cache_memory_usage`: Sets a rough target for the desired memory usage of the caches. Defaults to `null`.

  * `min_cache_ttl`: Sets a limit under which newer cache entries are not evicted and is only applied when caches are actively being evicted/`max_cache_memory_usage` has been exceeded. This is to protect hot caches from being emptied while Synapse is evicting due to memory. Defaults to `null`.

Example configuration:
```yaml
caches:
  global_factor: 1.0
  per_cache_factors:
    get_users_who_share_room_with_user: 2.0
  sync_response_cache_duration: 2m
  cache_autotuning:
    max_cache_memory_usage: 1024M
    target_cache_memory_usage: 758M
    min_cache_ttl: 5m
```

### Reloading cache factors

The cache factors (i.e. `caches.global_factor` and `caches.per_cache_factors`)  may be reloaded at any time by sending a [`SIGHUP`](https://en.wikipedia.org/wiki/SIGHUP) signal to Synapse using e.g.

```commandline
kill -HUP [PID_OF_SYNAPSE_PROCESS]
```

If you are running multiple workers, you must individually update the worker config file and send this signal to each worker process.

If you're using the [example systemd service](https://github.com/element-hq/synapse/blob/develop/contrib/systemd/matrix-synapse.service) file in Synapse's `contrib` directory, you can send a `SIGHUP` signal by using `systemctl reload matrix-synapse`.

---
## Database

Config options related to database settings.

---
### `database`

*(object)* The `database` setting defines the database that synapse uses to store all of its data.

For more information on using Synapse with Postgres, see [here](../../postgres.md).

This setting has the following sub-options:

* `name` (string): This option specifies the database engine to use: either `sqlite3` (for SQLite) or `psycopg2` (for PostgreSQL). If no name is specified Synapse will default to SQLite. Defaults to `"sqlite3"`.

* `txn_limit` (integer): Gives the maximum number of transactions to run per connection before reconnecting. 0 means no limit. Defaults to `0`.

* `allow_unsafe_locale` (boolean): This option is specific to Postgres. Under the default behavior, Synapse will refuse to start if the postgres db is set to a non-C locale. You can override this behavior (which is *not* recommended) by setting `allow_unsafe_locale` to true. Note that doing so may corrupt your database. You can find more information [here](../../postgres.md#fixing-incorrect-collate-or-ctype) and [here](https://wiki.postgresql.org/wiki/Locale_data_changes). Defaults to `false`.

* `args` (object): Gives options which are passed through to the database engine, except for options starting with `cp_`, which are used to configure the Twisted connection pool. For a reference to valid arguments, see:
  * for [sqlite](https://docs.python.org/3/library/sqlite3.html#sqlite3.connect)
  * for [postgres](https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-PARAMKEYWORDS)
  * for [the connection pool](https://docs.twistedmatrix.com/en/stable/api/twisted.enterprise.adbapi.ConnectionPool.html#__init__)

Example configurations:
```yaml
database:
  name: sqlite3
  args:
    database: /path/to/homeserver.db
```

```yaml
database:
  name: psycopg2
  txn_limit: 10000
  args:
    user: synapse_user
    password: secretpassword
    dbname: synapse
    host: localhost
    port: 5432
    cp_min: 5
    cp_max: 10
```
---
### `databases`

*(object)* The `databases` option allows specifying a mapping between certain database tables and database host details, spreading the load of a single Synapse instance across multiple database backends. This is often referred to as "database sharding". This option is only supported for PostgreSQL database backends.

**Important note:** This is a supported option, but is not currently used in production by the Matrix.org Foundation. Proceed with caution and always make backups.

`databases` is a dictionary of arbitrarily-named database entries. Each entry is equivalent to the value of the `database` homeserver config option (see above), with the addition of a `data_stores` key. `data_stores` is an array of strings that specifies the data store(s) (a defined label for a set of tables) that should be stored on the associated database backend entry.

The currently defined values for `data_stores` are:

* `"state"`: Database that relates to state groups will be stored in this database.

  Specifically, that means the following tables:
  * `state_groups`
  * `state_group_edges`
  * `state_groups_state`

  And the following sequences:
  * `state_groups_seq_id`

* `"main"`: All other database tables and sequences.

All databases will end up with additional tables used for tracking database schema migrations and any pending background updates. Synapse will create these automatically on startup when checking for and/or performing database schema migrations.

To migrate an existing database configuration (e.g. all tables on a single database) to a different configuration (e.g. the "main" data store on one database, and "state" on another), do the following:

1. Take a backup of your existing database. Things can and do go wrong and database corruption is no joke!
2. Ensure all pending database migrations have been applied and background updates have run. The simplest way to do this is to use the `update_synapse_database` script supplied with your Synapse installation.

   ```sh
   update_synapse_database --database-config homeserver.yaml --run-background-updates
   ```

3. Copy over the necessary tables and sequences from one database to the other. Tables relating to database migrations, schemas, schema versions and background updates should **not** be copied.

   As an example, say that you'd like to split out the "state" data store from an existing database which currently contains all data stores.

   Simply copy the tables and sequences defined above for the "state" datastore from the existing database to the secondary database. As noted above, additional tables will be created in the secondary database when Synapse is started.

4. Modify/create the `databases` option in your `homeserver.yaml` to match the desired database configuration.
5. Start Synapse. Check that it starts up successfully and that things generally seem to be working.
6. Drop the old tables that were copied in step 3.

Only one of the options `database` or `databases` may be specified in your config, but not both.

Defaults to `{}`.

Example configuration:
```yaml
databases:
  basement_box:
    name: psycopg2
    txn_limit: 10000
    data_stores:
    - main
    args:
      user: synapse_user
      password: secretpassword
      dbname: synapse_main
      host: localhost
      port: 5432
      cp_min: 5
      cp_max: 10
  my_other_database:
    name: psycopg2
    txn_limit: 10000
    data_stores:
    - state
    args:
      user: synapse_user
      password: secretpassword
      dbname: synapse_state
      host: localhost
      port: 5432
      cp_min: 5
      cp_max: 10
```
---
## Logging

Config options related to logging.

---
### `log_config`

*(string|null)* This option specifies a yaml python logging config file as described [here](https://docs.python.org/3/library/logging.config.html#configuration-dictionary-schema). Defaults to `null`.

Example configuration:
```yaml
log_config: CONFDIR/SERVERNAME.log.config
```
---
## Ratelimiting

Options related to ratelimiting in Synapse.

Each ratelimiting configuration is made of two parameters:
- `per_second`: number of requests a client can send per second.
- `burst_count`: number of requests a client can send before being throttled.

---
### `rc_message`

*(object)* Ratelimiting settings for client messaging.

This is a ratelimiting option for messages that ratelimits sending based on the account the client is using.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_message:
  per_second: 0.2
  burst_count: 10.0
```

Example configuration:
```yaml
rc_message:
  per_second: 0.5
  burst_count: 15.0
```
---
### `rc_registration`

*(object)* This option ratelimits registration requests based on the client's IP address.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_registration:
  per_second: 0.17
  burst_count: 3.0
```

Example configuration:
```yaml
rc_registration:
  per_second: 0.15
  burst_count: 2.0
```
---
### `rc_registration_token_validity`

*(object)* This option checks the validity of registration tokens that ratelimits requests based on the client's IP address.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_registration_token_validity:
  per_second: 0.1
  burst_count: 5.0
```

Example configuration:
```yaml
rc_registration_token_validity:
  per_second: 0.3
  burst_count: 6.0
```
---
### `rc_login`

*(object)* This option specifies several limits for login.

This setting has the following sub-options:

* `address` (object): Ratelimits login requests based on the client's IP address. Defaults to `{"per_second": 0.003, "burst_count": 5.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

* `account` (object): Ratelimits login requests based on the account the client is attempting to log into. Defaults to `{"per_second": 0.003, "burst_count": 5.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

* `failed_attempts` (object): Ratelimits login requests based on the account the client is attempting to log into, based on the amount of failed login attempts for this account. Defaults to `{"per_second": 0.17, "burst_count": 3.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

Example configuration:
```yaml
rc_login:
  address:
    per_second: 0.15
    burst_count: 5.0
  account:
    per_second: 0.18
    burst_count: 4.0
  failed_attempts:
    per_second: 0.19
    burst_count: 7.0
```
---
### `rc_admin_redaction`

*(object)* This option sets ratelimiting redactions by room admins. If this is not explicitly set then it uses the same ratelimiting as per `rc_message`. This is useful to allow room admins to deal with abuse quickly.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Example configuration:
```yaml
rc_admin_redaction:
  per_second: 1.0
  burst_count: 50.0
```
---
### `rc_joins`

*(object)* This option allows for ratelimiting number of rooms a user can join.

This setting has the following sub-options:

* `local` (object): Ratelimits when users are joining rooms the server is already in. Defaults to `{"per_second": 0.1, "burst_count": 10.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

* `remote` (object): Ratelimits when users are trying to join rooms not on the server (which can be more computationally expensive than restricting locally). Defaults to `{"per_second": 0.01, "burst_count": 10.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

Example configuration:
```yaml
rc_joins:
  local:
    per_second: 0.2
    burst_count: 15.0
  remote:
    per_second: 0.03
    burst_count: 12.0
```
---
### `rc_joins_per_room`

*(object)* This option allows admins to ratelimit joins to a room based on the number of recent joins (local or remote) to that room. It is intended to mitigate mass-join spam waves which target multiple homeservers.

_Added in Synapse 1.64.0._

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_joins_per_room:
  per_second: 1.0
  burst_count: 10.0
```

Example configuration:
```yaml
rc_joins_per_room:
  per_second: 1.0
  burst_count: 10.0
```
---
### `rc_3pid_validation`

*(object)* This option ratelimits how often a user or IP can attempt to validate a 3PID.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_3pid_validation:
  per_second: 0.003
  burst_count: 5.0
```

Example configuration:
```yaml
rc_3pid_validation:
  per_second: 0.003
  burst_count: 5.0
```
---
### `rc_invites`

*(object)* This option sets ratelimiting how often invites can be sent in a room or to a specific user.

Client requests that invite user(s) when [creating a room](https://spec.matrix.org/v1.2/client-server-api/#post_matrixclientv3createroom) will count against the `rc_invites.per_room` limit, whereas client requests to [invite a single user to a room](https://spec.matrix.org/v1.2/client-server-api/#post_matrixclientv3roomsroomidinvite) will count against both the `rc_invites.per_user` and `rc_invites.per_room` limits.

Federation requests to invite a user will count against the `rc_invites.per_user` limit only, as Synapse presumes ratelimiting by room will be done by the sending server.

_Changed in version 1.63:_ added the `per_issuer` limit.

This setting has the following sub-options:

* `per_room` (object): Applies to the room of the invitation. Defaults to `{"per_second": 0.3, "burst_count": 10.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

* `per_user` (object): Applies to the *receiver* of the invite, rather than the sender, meaning that a `rc_invite.per_user.burst_count` of 5 mandates that a single user cannot *receive* more than a burst of 5 invites at a time. Defaults to `{"per_second": 0.003, "burst_count": 5.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

* `per_issuer` (object): Applies to the *issuer* of the invite, meaning that a `rc_invite.per_issuer.burst_count` of 5 mandates that single user cannot *send* more than a burst of 5 invites at a time. Defaults to `{"per_second": 0.3, "burst_count": 10.0}`.

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

Example configuration:
```yaml
rc_invites:
  per_room:
    per_second: 0.5
    burst_count: 5.0
  per_user:
    per_second: 0.004
    burst_count: 3.0
  per_issuer:
    per_second: 0.5
    burst_count: 5.0
```
---
### `rc_third_party_invite`

*(object)* This option ratelimits 3PID invites (i.e. invites sent to a third-party ID such as an email address or a phone number) based on the account that's sending the invite.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_third_party_invite:
  per_second: 0.2
  burst_count: 10.0
```
---
### `rc_media_create`

*(object)* This option ratelimits creation of MXC URIs via the `/_matrix/media/v1/create` endpoint based on the account that's creating the media.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_media_create:
  per_second: 10.0
  burst_count: 50.0
```
---
### `rc_federation`

*(object)* Defines limits on federation requests.

This setting has the following sub-options:

* `window_size` (integer): Window size in milliseconds. Defaults to `1000`.

* `sleep_limit` (integer): Number of federation requests from a single server in a window before the server will delay processing the request. Defaults to `10`.

* `sleep_delay` (integer): Duration in milliseconds to delay processing events from remote servers by if they go over the sleep limit. Defaults to `500`.

* `reject_limit` (integer): Maximum number of concurrent federation requests allowed from a single server. Defaults to `50`.

* `concurrent` (integer): Number of federation requests to concurrently process from a single server. Defaults to `3`.

Example configuration:
```yaml
rc_federation:
  window_size: 750
  sleep_limit: 15
  sleep_delay: 400
  reject_limit: 40
  concurrent: 5
```
---
### `rc_presence`

*(object)* This option sets ratelimiting for presence.

This setting has the following sub-options:

* `per_user` (object): Sets rate limits on how often a specific users' presence updates are evaluated. Ratelimited presence updates sent via sync are ignored, and no error is returned to the client. This option also sets the rate limit for the [`PUT /_matrix/client/v3/presence/{userId}/status`] endpoint.

  [`PUT /_matrix/client/v3/presence/{userId}/status`]:
    <https://spec.matrix.org/latest/client-server-api/#put_matrixclientv3presenceuseridstatus>

  This setting has the following sub-options:

  * `per_second` (number): Maximum number of requests a client can send per second.

  * `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_presence:
  per_user:
    per_second: 0.1
    burst_count: 1.0
```

Example configuration:
```yaml
rc_presence:
  per_user:
    per_second: 0.05
    burst_count: 1.0
```
---
### `rc_delayed_event_mgmt`

*(object)* Ratelimiting settings for delayed event management.

This is a ratelimiting option that ratelimits attempts to restart, cancel, or view delayed events based on the sending client's account, or its source IP when requests are unauthenticated.

Attempts to create or send delayed events are ratelimited not by this setting, but by `rc_message`.

Setting this to a high value allows clients to make delayed event management requests often (such as repeatedly restarting a delayed event with a short timeout, or restarting several different delayed events all at once) without the risk of being ratelimited.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_delayed_event_mgmt:
  per_second: 1.0
  burst_count: 5.0
```

Example configuration:
```yaml
rc_delayed_event_mgmt:
  per_second: 2.0
  burst_count: 20.0
```
---
### `rc_reports`

*(object)* Ratelimiting settings for reporting content.
This is a ratelimiting option that ratelimits reports made by users about content they see.
Setting this to a high value allows users to report content quickly, possibly in duplicate. This can result in higher database usage.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_reports:
  per_second: 1.0
  burst_count: 5.0
```

Example configuration:
```yaml
rc_reports:
  per_second: 2.0
  burst_count: 20.0
```
---
### `rc_room_creation`

*(object)* Sets rate limits for how often users are able to create rooms.

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_room_creation:
  per_second: 0.016
  burst_count: 10.0
```

Example configuration:
```yaml
rc_room_creation:
  per_second: 1.0
  burst_count: 5.0
```
---
### `rc_user_directory`

*(object)* This option allows admins to ratelimit searches in the user directory.

_Added in Synapse 1.145.0._

This setting has the following sub-options:

* `per_second` (number): Maximum number of requests a client can send per second.

* `burst_count` (number): Maximum number of requests a client can send before being throttled.

Default configuration:
```yaml
rc_user_directory:
  per_second: 0.016
  burst_count: 200.0
```
---
### `federation_rr_transactions_per_room_per_second`

*(integer)* Sets outgoing federation transaction frequency for sending read-receipts, per-room.

If we end up trying to send out more read-receipts, they will get buffered up into fewer transactions.

Defaults to `50`.

Example configuration:
```yaml
federation_rr_transactions_per_room_per_second: 40
```
---
## Media Store

Config options related to Synapse's media store.

---
### `enable_authenticated_media`

*(boolean)* When set to true, all subsequent media uploads will be marked as authenticated, and will not be available over legacy unauthenticated media endpoints (`/_matrix/media/(r0|v3|v1)/download` and `/_matrix/media/(r0|v3|v1)/thumbnail`) – requests for authenticated media over these endpoints will result in a 404. All media, including authenticated media, will be available over the authenticated media endpoints `_matrix/client/v1/media/download` and `_matrix/client/v1/media/thumbnail`. Media uploaded prior to setting this option to true will still be available over the legacy endpoints. Note if the setting is switched to false after enabling, media marked as authenticated will be available over legacy endpoints. Defaults to true (previously false). In a future release of Synapse, this option will be removed and become always-on.

In all cases, authenticated requests to download media will succeed, but for unauthenticated requests, this case-by-case breakdown describes whether media downloads are permitted:

* `enable_authenticated_media = False`:
  * unauthenticated client or homeserver requesting local media: allowed
  * unauthenticated client or homeserver requesting remote media: allowed as long as the media is in the cache, or as long as the remote homeserver does not require authentication to retrieve the media
* `enable_authenticated_media = True`:
  * unauthenticated client or homeserver requesting local media: allowed if the media was stored on the server whilst `enable_authenticated_media` was `False` (or in a previous Synapse version where this option did not exist); otherwise denied.
  * unauthenticated client or homeserver requesting remote media: the same as for local media; allowed if the media was stored on the server whilst `enable_authenticated_media` was `False` (or in a previous Synapse version where this option did not exist); otherwise denied.

It is especially notable that media downloaded before this option existed (in older Synapse versions), or whilst this option was set to `False`, will perpetually be available over the legacy, unauthenticated endpoint, even after this option is set to `True`. This is for backwards compatibility with older clients and homeservers that do not yet support requesting authenticated media; those older clients or homeservers will not be cut off from media they can already see.

_Changed in Synapse 1.120:_ This option now defaults to `True` when not set, whereas before this version it defaulted to `False`.

Defaults to `true`.

Example configuration:
```yaml
enable_authenticated_media: false
```
---
### `enable_media_repo`

*(boolean)* Enable the media store service in the Synapse master. Set to false if you are using a separate media store worker. Defaults to `true`.

Example configuration:
```yaml
enable_media_repo: false
```
---
### `enable_local_media_storage`

*(boolean)* Enable the local on-disk media storage provider. When disabled, media is stored only in configured `media_storage_providers` and temporary files are used for processing.
**Warning:** If this option is set to `false` and no `media_storage_providers` are configured, all media requests will return 404 errors as there will be no storage backend available. Defaults to `true`.

Example configuration:
```yaml
enable_local_media_storage: false
```
---
### `media_store_path`

*(string)* Directory where uploaded images and attachments are stored. Defaults to `"media_store"`.

Example configuration:
```yaml
media_store_path: DATADIR/media_store
```
---
### `max_pending_media_uploads`

*(integer)* How many *pending media uploads* can a given user have? A pending media upload is a created MXC URI that (a) is not expired (the `unused_expires_at` timestamp has not passed) and (b) the media has not yet been uploaded for. Defaults to `5`.

Example configuration:
```yaml
max_pending_media_uploads: 5
```
---
### `unused_expiration_time`

*(duration)* How long to wait in milliseconds before expiring created media IDs. Defaults to `"24h"`.

Example configuration:
```yaml
unused_expiration_time: 1h
```
---
### `media_storage_providers`

*(array)* Media storage providers allow media to be stored in different locations. Defaults to `[]`.

Options for each entry include:

* `module` (string): Type of resource, e.g. `file_system`.

* `store_local` (boolean): Whether to store newly uploaded local files.

* `store_remote` (boolean): Whether to store newly downloaded local files.

* `store_synchronous` (boolean): Whether to wait for successful storage for local uploads.

* `config` (object): Sets a path to the resource through the `directory` option.

  This setting has the following sub-options:

  * `directory` (string): Path to the resource.

Example configuration:
```yaml
media_storage_providers:
- module: file_system
  store_local: false
  store_remote: false
  store_synchronous: false
  config:
    directory: /mnt/some/other/directory
```
---
### `max_upload_size`

*(byte size)* The largest allowed upload size in bytes.

If you are using a reverse proxy you may also need to set this value in your reverse proxy's config. Notably Nginx has a small max body size by default. See [here](../../reverse_proxy.md) for more on using a reverse proxy with Synapse.

Defaults to `"50M"`.

Example configuration:
```yaml
max_upload_size: 60M
```
---
### `media_upload_limits`

*(array)* A list of media upload limits defining how much data a given user can upload in a given time period.
These limits are applied in addition to the `max_upload_size` limit above (which applies to individual uploads).

An empty list means no limits are applied.

These settings can be overridden using the `get_media_upload_limits_for_user` module API [callback](../../modules/media_repository_callbacks.md#get_media_upload_limits_for_user).

Defaults to `[]`.

Options for each entry include:

* `time_period` (duration): The time period over which the limit applies. Required.

* `max_size` (byte size): Amount of data that can be uploaded in the time period by the user. Required.

* `info_uri` (string): URI returned to the client for where the user can find information about the upload limit and how users can reduce their upload usage or request an upload limit increase. Optional. If not set, Synapse serves a built-in page (customisable via the `media_upload_limit_exceeded.html` template) and uses its URL instead.

* `can_upgrade` (boolean): Value returned to the client for whether the limit can be increased. Defaults to `false`.

Example configuration:
```yaml
media_upload_limits:
- time_period: 1h
  max_size: 100M
  info_uri: https://example.com/quota#hour
- time_period: 1w
  max_size: 500M
  info_uri: https://example.com/quota
  can_upgrade: true
```
---
### `max_image_pixels`

*(byte size)* Maximum number of pixels that will be thumbnailed. Defaults to `"32M"`.

Example configuration:
```yaml
max_image_pixels: 35M
```
---
### `remote_media_download_burst_count`

*(byte size)* Remote media downloads are ratelimited using a [leaky bucket algorithm](https://en.wikipedia.org/wiki/Leaky_bucket), where a given "bucket" is keyed to the IP address of the requester when requesting remote media downloads. This configuration option sets the size of the bucket against which the size in bytes of downloads are penalized – if the bucket is full, i.e. a given number of bytes have already been downloaded, further downloads will be denied until the bucket drains. See also `remote_media_download_per_second` which determines the rate at which the "bucket" is emptied and thus has available space to authorize new requests. Defaults to `"500MiB"`.

Example configuration:
```yaml
remote_media_download_burst_count: 200M
```
---
### `remote_media_download_per_second`

*(byte size)* Works in conjunction with `remote_media_download_burst_count` to ratelimit remote media downloads – this configuration option determines the rate at which the "bucket" (see above) leaks in bytes per second. As requests are made to download remote media, the size of those requests in bytes is added to the bucket, and once the bucket has reached it's capacity, no more requests will be allowed until a number of bytes has "drained" from the bucket. This setting determines the rate at which bytes drain from the bucket, with the practical effect that the larger the number, the faster the bucket leaks, allowing for more bytes downloaded over a shorter period of time. Defaults to 87KiB per second. See also `remote_media_download_burst_count`. Defaults to `"87KiB"`.

Example configuration:
```yaml
remote_media_download_per_second: 40K
```
---
### `prevent_media_downloads_from`

*(array)* A list of domains to never download media from. Media from these domains that is already downloaded will not be deleted, but will be inaccessible to users. This option does not affect admin APIs trying to download/operate on media.

This will not prevent the listed domains from accessing media themselves. It simply prevents users on this server from downloading media originating from the listed servers.

This will have no effect on media originating from the local server. This only affects media downloaded from other Matrix servers, to control URL previews see [`url_preview_ip_range_blacklist`](#url_preview_ip_range_blacklist) or [`url_preview_url_blacklist`](#url_preview_url_blacklist).

Defaults to `[]`.

Example configuration:
```yaml
prevent_media_downloads_from:
- evil.example.org
- evil2.example.org
```
---
### `dynamic_thumbnails`

*(boolean)* Whether to generate new thumbnails on the fly to precisely match the resolution requested by the client. If true then whenever a new resolution is requested by the client the server will generate a new thumbnail. If false the server will pick a thumbnail from a precalculated list. Defaults to `false`.

Example configuration:
```yaml
dynamic_thumbnails: true
```
---
### `thumbnail_sizes`

*(array)* List of thumbnails to precalculate when an image is uploaded.

Options for each entry include:

* `width` (integer): Width of the generated thumbnail.

* `height` (integer): Height of the generated thumbnail.

* `method` (string): Method to fit the thumbnail dimensions. Current options are `crop` and `scale`.

Default configuration:
```yaml
thumbnail_sizes:
- width: 32
  height: 32
  method: crop
- width: 96
  height: 96
  method: crop
- width: 320
  height: 240
  method: scale
- width: 640
  height: 480
  method: scale
- width: 800
  height: 600
  method: scale
```
---
### `media_retention`

*(object)* Controls whether local media and entries in the remote media cache (media that is downloaded from other homeservers) should be removed under certain conditions, typically for the purpose of saving space.

Purging media files will be the carried out by the media worker (that is, the worker that has the `enable_media_repo` homeserver config option set to `true`). This may be the main process.

The `media_retention.local_media_lifetime` and `media_retention.remote_media_lifetime` config options control whether media will be purged if it has not been accessed in a given amount of time. Note that media is "accessed" when loaded in a room in a client, or otherwise downloaded by a local or remote user. If the media has never been accessed, the media's creation time is used instead. Both thumbnails and the original media will be removed. If either of these options are unset, then media of that type will not be purged.

Local or cached remote media that has been [quarantined](../../admin_api/media_admin_api.md#quarantining-media-in-a-room) will not be deleted. Similarly, local media that has been marked as [protected from quarantine](../../admin_api/media_admin_api.md#protecting-media-from-being-quarantined) will not be deleted.

This setting has the following sub-options:

* `local_media_lifetime`: Duration without access to a local media resource after which it will be purged. If the media has never been accessed, the media's creation time is used instead. Both thumbnails and the original media will be removed. If unset or null, local media will not be purged. Defaults to `null`.

* `remote_media_lifetime`: Duration without access to a remote media resource after which it will be purged. If the media has never been accessed, the media's creation time is used instead. Both thumbnails and the original media will be removed. If unset or null, remote media will not be purged. Defaults to `null`.

Example configuration:
```yaml
media_retention:
  local_media_lifetime: 90d
  remote_media_lifetime: 14d
```
---
### `url_preview_enabled`

*(boolean)* This setting determines whether the preview URL API is enabled. Set to true to enable. If enabled you must specify a `url_preview_ip_range_blacklist` blacklist. Defaults to `false`.

Example configuration:
```yaml
url_preview_enabled: true
```
---
### `url_preview_ip_range_blacklist`

*(array|null)* List of IP address CIDR ranges that the URL preview spider is denied from accessing. There are no defaults: you must explicitly specify a list for URL previewing to work. You should specify any internal services in your network that you do not want synapse to try to connect to, otherwise anyone in any Matrix room could cause your synapse to issue arbitrary GET requests to your internal services, causing serious security issues.

(0.0.0.0 and :: are always blacklisted, whether or not they are explicitly listed here, since they correspond to unroutable addresses.)

This must be specified if `url_preview_enabled` is set. It is recommended that you use the following example list as a starting point.

Note: The value is ignored when an HTTP proxy is in use.

Defaults to `null`.

Example configuration:
```yaml
url_preview_ip_range_blacklist:
- 127.0.0.0/8
- 10.0.0.0/8
- 172.16.0.0/12
- 192.168.0.0/16
- 100.64.0.0/10
- 192.0.0.0/24
- 169.254.0.0/16
- 192.88.99.0/24
- 198.18.0.0/15
- 192.0.2.0/24
- 198.51.100.0/24
- 203.0.113.0/24
- 224.0.0.0/4
- ::1/128
- fe80::/10
- fc00::/7
- 2001:db8::/32
- ff00::/8
- fec0::/10
```
---
### `url_preview_ip_range_whitelist`

*(array)* This option sets a list of IP address CIDR ranges that the URL preview spider is allowed to access even if they are specified in `url_preview_ip_range_blacklist`. This is useful for specifying exceptions to wide-ranging blacklisted target IP ranges – e.g. for enabling URL previews for a specific private website only visible in your network. Defaults to `[]`.

Example configuration:
```yaml
url_preview_ip_range_whitelist:
- 192.168.1.1
```
---
### `url_preview_url_blacklist`

*(array)* Optional list of URL matches that the URL preview spider is denied from accessing. This is a usability feature, not a security one. You should use `url_preview_ip_range_blacklist` in preference to this, otherwise someone could define a public DNS entry that points to a private IP address and circumvent the blacklist. Applications that perform redirects or serve different content when detecting that Synapse is accessing them can also bypass the blacklist. This is more useful if you know there is an entire shape of URL that you know that you do not want Synapse to preview.

Each list entry is a dictionary of url component attributes as returned by urlparse.urlsplit as applied to the absolute form of the URL. See [here](https://docs.python.org/2/library/urlparse.html#urlparse.urlsplit) for more information. Some examples are:

* `username`
* `netloc`
* `scheme`
* `path`

The values of the dictionary are treated as a filename match pattern applied to that component of URLs, unless they start with a ^ in which case they are treated as a regular expression match. If all the specified component matches for a given list item succeed, the URL is blacklisted.

Defaults to `[]`.

Example configuration:
```yaml
url_preview_url_blacklist:
- username: '*'
- netloc: google.com
- netloc: '*.google.com'
- scheme: http
- netloc: www.acme.com
  path: /foo
- netloc: ^[0-9]+.[0-9]+.[0-9]+.[0-9]+$
```
---
### `max_spider_size`

*(byte size)* The largest allowed URL preview spidering size in bytes. Defaults to `"10M"`.

Example configuration:
```yaml
max_spider_size: 8M
```
---
### `url_preview_accept_language`

*(array)* A list of values for the Accept-Language HTTP header used when downloading webpages during URL preview generation. This allows Synapse to specify the preferred languages that URL previews should be in when communicating with remote servers.

Each value is a IETF language tag; a 2-3 letter identifier for a language, optionally followed by subtags separated by `-`, specifying a country or region variant.

Multiple values can be provided, and a weight can be added to each by using quality value syntax (;q=). `*` translates to any language.

Default configuration:
```yaml
url_preview_accept_language:
- en
```

Example configuration:
```yaml
url_preview_accept_language:
- en-UK
- en-US;q=0.9
- fr;q=0.8
- '*;q=0.7'
```
---
### `oembed`

*(object)* oEmbed allows for easier embedding content from a website. It can be used for generating URLs previews of services which support it. A default list of oEmbed providers is included with Synapse.

This setting has the following sub-options:

* `disable_default_providers` (boolean): Do not use Synapse's default list of oEmbed providers. Defaults to `false`.

* `additional_providers` (array): Additional files with oEmbed configuration (each should be in the form of providers.json). Defaults to `[]`.

Example configuration:
```yaml
oembed:
  disable_default_providers: true
  additional_providers:
  - oembed/my_providers.json
```
---
## Captcha

See [here](../../CAPTCHA_SETUP.md) for full details on setting up captcha.

---
### `recaptcha_public_key`

*(string|null)* This homeserver's ReCAPTCHA public key. Must be specified if [`enable_registration_captcha`](#enable_registration_captcha) is enabled. Defaults to `null`.

Example configuration:
```yaml
recaptcha_public_key: YOUR_PUBLIC_KEY
```
---
### `recaptcha_public_key_path`

*(string|null)* An alternative to [`recaptcha_public_key`](#recaptcha_public_key): allows the public key to be specified in an external file.

The file should be a plain text file, containing only the public key. Synapse reads the public key from the given file once at startup.

_Added in Synapse 1.135.0._

Defaults to `null`.

Example configuration:
```yaml
recaptcha_public_key_path: /path/to/key/file
```
---
### `recaptcha_private_key`

*(string|null)* This homeserver's ReCAPTCHA private key. Must be specified if [`enable_registration_captcha`](#enable_registration_captcha) is enabled. Defaults to `null`.

Example configuration:
```yaml
recaptcha_private_key: YOUR_PRIVATE_KEY
```
---
### `recaptcha_private_key_path`

*(string|null)* An alternative to [`recaptcha_private_key`](#recaptcha_private_key): allows the private key to be specified in an external file.

The file should be a plain text file, containing only the private key. Synapse reads the private key from the given file once at startup.

_Added in Synapse 1.135.0._

Defaults to `null`.

Example configuration:
```yaml
recaptcha_private_key_path: /path/to/key/file
```
---
### `enable_registration_captcha`

*(boolean)* Set to `true` to require users to complete a CAPTCHA test when registering an account. Requires a valid ReCaptcha public/private key.

Note that [`enable_registration`](#enable_registration) must also be set to allow account registration.

Defaults to `false`.

Example configuration:
```yaml
enable_registration_captcha: true
```
---
### `recaptcha_siteverify_api`

*(string)* The API endpoint to use for verifying `m.login.recaptcha` responses. Defaults to `"https://www.recaptcha.net/recaptcha/api/siteverify"`.

Example configuration:
```yaml
recaptcha_siteverify_api: https://my.recaptcha.site
```
---
## TURN

Options related to adding a TURN server to Synapse.

---
### `turn_uris`

*(array)* The public URIs of the TURN server to give to clients. Defaults to `[]`.

Example configuration:
```yaml
turn_uris:
- turn:example.org
```
---
### `turn_shared_secret`

*(string|null)* The shared secret used to compute passwords for the TURN server. Defaults to `null`.

Example configuration:
```yaml
turn_shared_secret: YOUR_SHARED_SECRET
```
---
### `turn_shared_secret_path`

*(string|null)* An alternative to [`turn_shared_secret`](#turn_shared_secret): allows the shared secret to be specified in an external file.

The file should be a plain text file, containing only the shared secret. Synapse reads the shared secret from the given file once at startup.

_Added in Synapse 1.116.0._

Defaults to `null`.

Example configuration:
```yaml
turn_shared_secret_path: /path/to/secrets/file
```
---
### `turn_username`

*(string|null)* TURN server username if not using a token. Defaults to `null`.

Example configuration:
```yaml
turn_username: TURNSERVER_USERNAME
```
---
### `turn_password`

*(string|null)* TURN server password if not using a token. Defaults to `null`.

Example configuration:
```yaml
turn_password: TURNSERVER_PASSWORD
```
---
### `turn_user_lifetime`

*(duration)* How long generated TURN credentials last. Defaults to `"1h"`.

Example configuration:
```yaml
turn_user_lifetime: 2h
```
---
### `turn_allow_guests`

*(boolean)* Whether guests should be allowed to use the TURN server. If false, VoIP will be unreliable for guests. However, it does introduce a slight security risk as it allows users to connect to arbitrary endpoints without having first signed up for a valid account (e.g. by passing a CAPTCHA). Defaults to `true`.

Example configuration:
```yaml
turn_allow_guests: false
```
---
### `matrix_rtc`

*(object)* Options related to MatrixRTC. Defaults to `{}`.

This setting has the following sub-options:

* `transports` (array): A list of transport types and arguments to use for MatrixRTC connections. Defaults to `[]`.

  Options for each entry include:

  * `type` (string): The type of transport to use to connect to the selective forwarding unit (SFU).

  * `livekit_service_url` (string): The base URL of the LiveKit service. Should only be used with LiveKit-based transports.

Example configuration:
```yaml
matrix_rtc:
  transports:
  - type: livekit
    livekit_service_url: https://matrix-rtc.example.com/livekit/jwt
```
---
## Registration

Registration can be rate-limited using the parameters in the [Ratelimiting](#ratelimiting) section of this manual.

---
### `enable_registration`

*(boolean)* Enable registration for new users.

It is highly recommended that if you enable registration, you set one or more or the following options, to avoid abuse of your server by "bots":

* [`enable_registration_captcha`](#enable_registration_captcha)
* [`registrations_require_3pid`](#registrations_require_3pid)
* [`registration_requires_token`](#registration_requires_token)

(In order to enable registration without any verification, you must also set [`enable_registration_without_verification`](#enable_registration_without_verification).)

Note that even if this setting is disabled, new accounts can still be created via the admin API if [`registration_shared_secret`](#registration_shared_secret) is set.

Defaults to `false`.

Example configuration:
```yaml
enable_registration: true
```
---
### `enable_registration_without_verification`

*(boolean)* Enable registration without email or captcha verification. Note: this option is *not* recommended, as registration without verification is a known vector for spam and abuse. Has no effect unless [`enable_registration`](#enable_registration) is also enabled. Defaults to `false`.

Example configuration:
```yaml
enable_registration_without_verification: true
```
---
### `registrations_require_3pid`

*(array)* If this is set, users must provide all of the specified types of [3PID](https://spec.matrix.org/latest/appendices/#3pid-types) when registering an account.

Note that [`enable_registration`](#enable_registration) must also be set to allow account registration.

Defaults to `[]`.

Example configuration:
```yaml
registrations_require_3pid:
- email
- msisdn
```
---
### `disable_msisdn_registration`

*(boolean)* Explicitly disable asking for MSISDNs from the registration flow (overrides `registrations_require_3pid` if MSISDNs are set as required). Defaults to `false`.

Example configuration:
```yaml
disable_msisdn_registration: true
```
---
### `allowed_local_3pids`

*(array|null)* Mandate that users are only allowed to associate certain formats of 3PIDs with accounts on this server, as specified by the `medium` and `pattern` sub-options. `pattern` is a [Perl-like regular expression](https://docs.python.org/3/library/re.html#module-re).

More information about 3PIDs, allowed `medium` types and their `address` syntax can be found [in the Matrix spec](https://spec.matrix.org/latest/appendices/#3pid-types).

Defaults to `null`.

Options for each entry include:

* `medium` (string): The medium for which to allow 3PID association.

* `pattern` (string): A [Perl-like regular expression](https://docs.python.org/3/library/re.html#module-re) allowing association of a 3PID to a local account if it matches the given format.

Example configuration:
```yaml
allowed_local_3pids:
- medium: email
  pattern: ^[^@]+@matrix\.org$
- medium: email
  pattern: ^[^@]+@vector\.im$
- medium: msisdn
  pattern: ^44\d{10}$
```
---
### `enable_3pid_lookup`

*(boolean)* Enable 3PIDs lookup requests to identity servers from this server. Defaults to `true`.

Example configuration:
```yaml
enable_3pid_lookup: false
```
---
### `registration_requires_token`

*(boolean)* Require users to submit a token during registration. Tokens can be managed using the admin [API](../administration/admin_api/registration_tokens.md). Disabling this option will not delete any tokens previously generated.

Note that [`enable_registration`](#enable_registration) must also be set to allow account registration.

Defaults to `false`.

Example configuration:
```yaml
registration_requires_token: true
```
---
### `registration_shared_secret`

*(string|null)* If set, allows registration of standard or admin accounts by anyone who has the shared secret, even if [`enable_registration`](#enable_registration) is not set.

This is primarily intended for use with the `register_new_matrix_user` script (see [Registering a user](../../setup/installation.md#registering-a-user)); however, the interface is [documented](../../admin_api/register_api.html).

Replacing an existing `registration_shared_secret` with a new one requires users of the [Shared-Secret Registration API](../../admin_api/register_api.html) to start using the new secret for requesting any further one-time nonces.

> ⚠️ **Warning** – The additional consequences of replacing [`macaroon_secret_key`](#macaroon_secret_key) will apply in case it delegates to `registration_shared_secret`.

See also [`registration_shared_secret_path`](#registration_shared_secret_path).

Defaults to `null`.

Example configuration:
```yaml
registration_shared_secret: <PRIVATE STRING>
```
---
### `registration_shared_secret_path`

*(string|null)* An alternative to [`registration_shared_secret`](#registration_shared_secret): allows the shared secret to be specified in an external file.

The file should be a plain text file, containing only the shared secret.

If this file does not exist, Synapse will create a new shared secret on startup and store it in this file.

_Added in Synapse 1.67.0._

Defaults to `null`.

Example configuration:
```yaml
registration_shared_secret_path: /path/to/secrets/file
```
---
### `bcrypt_rounds`

*(integer)* Set the number of bcrypt rounds used to generate password hash. Larger numbers increase the work factor needed to generate the hash. The default number is 12 (which equates to 2^12 rounds). N.B. that increasing this will exponentially increase the time required to register or login - e.g. 24 => 2^24 rounds which will take >20 mins. Defaults to `12`.

Example configuration:
```yaml
bcrypt_rounds: 14
```
---
### `allow_guest_access`

*(boolean)* Allows users to register as guests without a password/email/etc, and participate in rooms hosted on this server which have been made accessible to anonymous users. Defaults to `false`.

Example configuration:
```yaml
allow_guest_access: true
```
---
### `default_identity_server`

*(string|null)* The identity server which we suggest that clients should use when users log in on this server.

(By default, no suggestion is made, so it is left up to the client. This setting is ignored unless `public_baseurl` is also explicitly set.)

Defaults to `null`.

Example configuration:
```yaml
default_identity_server: https://matrix.org
```
---
### `account_threepid_delegates`

*(object)* Delegate verification of phone numbers to an identity server.

When a user wishes to add a phone number to their account, we need to verify that they actually own that phone number, which requires sending them a text message (SMS). Currently Synapse does not support sending those texts itself and instead delegates the task to an identity server. The base URI for the identity server to be used is specified by the `account_threepid_delegates.msisdn` option.

If this is left unspecified, Synapse will not allow users to add phone numbers to their account.

(Servers handling the these requests must answer the `/requestToken` endpoints defined by the Matrix Identity Service API [specification](https://matrix.org/docs/spec/identity_service/latest).)

*Deprecated in Synapse 1.64.0*: The `email` option is deprecated.

*Removed in Synapse 1.66.0*: The `email` option has been removed. If present, Synapse will report a configuration error on startup.

Defaults to `{}`.

This setting has the following sub-options:

* `msisdn` (string|null): Identity server base URI for MSISDN (phone numbers). See above.

Example configuration:
```yaml
account_threepid_delegates:
  msisdn: http://localhost:8090
```
---
### `enable_set_displayname`

*(boolean)* Whether users are allowed to change their displayname after it has been initially set. Useful when provisioning users based on the contents of a third-party directory.

Does not apply to server administrators.

Defaults to `true`.

Example configuration:
```yaml
enable_set_displayname: false
```
---
### `enable_set_avatar_url`

*(boolean)* Whether users are allowed to change their avatar after it has been initially set. Useful when provisioning users based on the contents of a third-party directory.

Does not apply to server administrators.

Defaults to `true`.

Example configuration:
```yaml
enable_set_avatar_url: false
```
---
### `enable_3pid_changes`

*(boolean)* Whether users can change the third-party IDs associated with their accounts (email address and msisdn). Defaults to `true`.

Example configuration:
```yaml
enable_3pid_changes: false
```
---
### `auto_join_rooms`

*(array)* Users who register on this homeserver will automatically be joined to the rooms listed under this option.

By default, any room aliases included in this list will be created as a publicly joinable room when the first user registers for the homeserver. If the room already exists, make certain it is a publicly joinable room, i.e. the join rule of the room must be set to `public`. You can find more options relating to auto-joining rooms below.

Invite-only rooms can also be auto-joined when setting `auto_join_mxid_localpart` to a user who's part of the invite-only rooms.

As Spaces are just rooms under the hood, Space aliases may also be used.

Defaults to `[]`.

Example configuration:
```yaml
auto_join_rooms:
- '#exampleroom:example.com'
- '#anotherexampleroom:example.com'
```
---
### `autocreate_auto_join_rooms`

*(boolean)* Where `auto_join_rooms` are specified, setting this flag ensures that the rooms exist by creating them when the first user on the homeserver registers. This option will not create Spaces.

By default the auto-created rooms are publicly joinable from any federated server. Use the `autocreate_auto_join_rooms_federated` and `autocreate_auto_join_room_preset` settings to customise this behaviour.

Setting to false means that if the rooms are not manually created, users cannot be auto-joined since they do not exist.

Defaults to `true`.

Example configuration:
```yaml
autocreate_auto_join_rooms: false
```
---
### `autocreate_auto_join_rooms_federated`

*(boolean)* Whether the rooms listed in `auto_join_rooms` that are auto-created are available via federation. Only has an effect if `autocreate_auto_join_rooms` is true.

Note that whether a room is federated cannot be modified after creation.

If true, the room will be joinable from other servers. If false, users from other homeservers are prevented from joining these rooms.

Defaults to `true`.

Example configuration:
```yaml
autocreate_auto_join_rooms_federated: false
```
---
### `autocreate_auto_join_room_preset`

*(string)* The room preset to use when auto-creating one of `auto_join_rooms`. Only has an effect if `autocreate_auto_join_rooms` is true.

Possible values for this option are:
* "public_chat": the room is joinable by anyone, including federated servers if `autocreate_auto_join_rooms_federated` is true (the default).
* "private_chat": an invitation is required to join these rooms.
* "trusted_private_chat": an invitation is required to join this room and the invitee is assigned a power level of 100 upon joining the room.

Each preset will set up a room in the same manner as if it were provided as the `preset` parameter when calling the [`POST /_matrix/client/v3/createRoom`](https://spec.matrix.org/latest/client-server-api/#post_matrixclientv3createroom) Client-Server API endpoint.

If a value of "private_chat" or "trusted_private_chat" is used then `auto_join_mxid_localpart` must also be configured.

Defaults to `"public_chat"`.

Example configuration:
```yaml
autocreate_auto_join_room_preset: private_chat
```
---
### `auto_join_mxid_localpart`

*(string|null)* The local part of the user id which is used to create `auto_join_rooms` if `autocreate_auto_join_rooms` is true. If this is not provided then the initial user account that registers will be used to create the rooms.

The user id is also used to invite new users to any auto-join rooms which are set to invite-only.

It *must* be configured if `autocreate_auto_join_room_preset` is set to "private_chat" or "trusted_private_chat".

Note that this must be specified in order for new users to be correctly invited to any auto-join rooms which have been set to invite-only (either at the time of creation or subsequently).

Note that, if the room already exists, this user must be joined and have the appropriate permissions to invite new members.

Defaults to `null`.

Example configuration:
```yaml
auto_join_mxid_localpart: system
```
---
### `auto_join_rooms_for_guests`

*(boolean)* When `auto_join_rooms` is specified, setting this flag to false prevents guest accounts from being automatically joined to the rooms. Defaults to `true`.

Example configuration:
```yaml
auto_join_rooms_for_guests: false
```
---
### `inhibit_user_in_use_error`

*(boolean)* Whether to inhibit errors raised when registering a new account if the user ID already exists. If turned on, requests to `/register/available` will always show a user ID as available, and Synapse won't raise an error when starting a registration with a user ID that already exists. However, Synapse will still raise an error if the registration completes and the username conflicts. Defaults to `false`.

Example configuration:
```yaml
inhibit_user_in_use_error: true
```
---
### `allow_underscore_prefixed_registration`

*(boolean)* Whether users are allowed to register with a underscore-prefixed localpart. By default, AppServices use prefixes like `_example` to namespace their associated ghost users. If turned on, this may result in clashes or confusion. Useful when provisioning users from an external identity provider. Defaults to `false`.

Example configuration:
```yaml
allow_underscore_prefixed_registration: true
```
---
## User session management

Config options related to user session management.

---
### `session_lifetime`

*(duration)* Time that a user's session remains valid for, after they log in.

Note that this is not currently compatible with guest logins.

Note also that this is calculated at login time: changes are not applied retrospectively to users who have already logged in.

Defaults to `"infinity"`.

Example configuration:
```yaml
session_lifetime: 24h
```
---
### `refreshable_access_token_lifetime`

*(duration)* Time that an access token remains valid for, if the session is using refresh tokens.

For more information about refresh tokens, please see the [manual](user_authentication/refresh_tokens.md).

Note that this only applies to clients which advertise support for refresh tokens.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

Defaults to `"5m"`.

Example configuration:
```yaml
refreshable_access_token_lifetime: 10m
```
---
### `refresh_token_lifetime`

*(duration)* Time that a refresh token remains valid for (provided that it is not exchanged for another one first). This option can be used to automatically log-out inactive sessions. Please see the manual for more information.

Note also that this is calculated at login time and refresh time: changes are not applied to existing sessions until they are refreshed.

Defaults to `"infinity"`.

Example configuration:
```yaml
refresh_token_lifetime: 24h
```
---
### `nonrefreshable_access_token_lifetime`

*(duration)* Time that an access token remains valid for, if the session is NOT using refresh tokens.

Please note that not all clients support refresh tokens, so setting this to a short value may be inconvenient for some users who will then be logged out frequently.

Note also that this is calculated at login time: changes are not applied retrospectively to existing sessions for users that have already logged in.

Defaults to `"infinity"`.

Example configuration:
```yaml
nonrefreshable_access_token_lifetime: 24h
```
---
### `ui_auth`

The amount of time to allow a user-interactive authentication session to be active.

This defaults to 0, meaning the user is queried for their credentials before every action, but this can be overridden to allow a single validation to be re-used. This weakens the protections afforded by the user-interactive authentication process, by allowing for multiple (and potentially different) operations to use the same validation session.

This is ignored for potentially "dangerous" operations (including deactivating an account, modifying an account password, adding a 3PID, and minting additional login tokens).

Use the `session_timeout` sub-option here to change the time allowed for credential validation.

Defaults to `0`.

Example configuration:
```yaml
ui_auth:
  session_timeout: 15s
```
---
### `login_via_existing_session`

*(object)* Matrix supports the ability of an existing session to mint a login token for another client.

Synapse disables this by default as it has security ramifications – a malicious client could use the mechanism to spawn more than one session.

This setting has the following sub-options:

* `enabled` (boolean): Enable login via existing session. Defaults to `false`.

* `require_ui_auth` (boolean): Require user-interactive authentication. Defaults to `true`.

* `token_timeout` (duration): Duration of time the generated token is valid. Defaults to `"5m"`.

Example configuration:
```yaml
login_via_existing_session:
  enabled: true
  require_ui_auth: false
  token_timeout: 5m
```
---
## Metrics

Config options related to metrics.

---
### `enable_metrics`

*(boolean)* Set to true to enable collection and rendering of performance metrics. Defaults to `false`.

Example configuration:
```yaml
enable_metrics: true
```
---
### `sentry`

*(object)* Use this option to enable sentry integration. Provide the DSN assigned to you by sentry with the `dsn` setting.

An optional `environment` field can be used to specify an environment. This allows for log maintenance based on different environments, ensuring better organization and analysis.

NOTE: While attempts are made to ensure that the logs don't contain any sensitive information, this cannot be guaranteed. By enabling this option the sentry server may therefore receive sensitive information, and it in turn may then disseminate sensitive information through insecure notification channels if so configured.

This setting has the following sub-options:

* `dsn` (string|null): The DSN assigned by sentry. If unset or null, sentry integration is disabled. Defaults to `null`.

* `environment` (string|null): Sentry environment. Defaults to `null`.

Example configuration:
```yaml
sentry:
  environment: production
  dsn: '...'
```
---
### `metrics_flags`

*(object)* Flags to enable Prometheus metrics which are not suitable to be enabled by default, either for performance reasons or limited use. Currently the only option is `known_servers`.

This setting has the following sub-options:

* `known_servers` (boolean): Publishes `synapse_federation_known_servers`, a gauge of the number of servers this homeserver knows about, including itself. May cause performance problems on large homeservers. Defaults to `false`.

Example configuration:
```yaml
metrics_flags:
  known_servers: true
```
---
### `report_stats`

*(boolean)* Whether or not to report homeserver usage statistics. This is originally set when generating the config. Set this option to true or false to change the current behavior. See [Reporting Homeserver Usage Statistics](../administration/monitoring/reporting_homeserver_usage_statistics.md) for information on what data is reported.

Statistics will be reported 5 minutes after Synapse starts, and then every 3 hours after that.

Defaults to `false`.

Example configuration:
```yaml
report_stats: true
```
---
### `report_stats_endpoint`

*(string)* The endpoint to report homeserver usage statistics to. Defaults to `"https://matrix.org/report-usage-stats/push"`.

Example configuration:
```yaml
report_stats_endpoint: https://example.com/report-usage-stats/push
```
---
## API Configuration

Config settings related to the client/server API.

---
### `room_prejoin_state`

*(object)* This setting controls the state that is shared with users upon receiving an invite to a room, or in reply to a knock on a room. By default, the following state events are shared with users:

- `m.room.join_rules`
- `m.room.canonical_alias`
- `m.room.avatar`
- `m.room.encryption`
- `m.room.name`
- `m.room.create`
- `m.room.topic`

*Changed in Synapse 1.74:* admins can filter the events in prejoin state based on their state key.

This setting has the following sub-options:

* `disable_default_event_types` (boolean): Set to `true` to disable the above defaults. If this is enabled, only the event types listed in `additional_event_types` are shared. Defaults to `false`.

* `additional_event_types` (array): A list of additional state events to include in the events to be shared. By default, this list is empty (so only the default event types are shared).

  Each entry in this list should be either a single string or a list of two strings.
  * A standalone string `t` represents all events with type `t` (i.e. with no restrictions on state keys).
  * A pair of strings `[t, s]` represents a single event with type `t` and state key `s`. The same type can appear in two entries with different state keys: in this situation, both state keys are included in prejoin state.

  Defaults to `[]`.

Example configuration:
```yaml
room_prejoin_state:
  disable_default_event_types: false
  additional_event_types:
  - org.example.custom.event.typeA
  - - org.example.custom.event.typeB
    - foo
  - - org.example.custom.event.typeC
    - bar
  - - org.example.custom.event.typeC
    - baz
```
---
### `track_puppeted_user_ips`

*(boolean)* We record the IP address of clients used to access the API for various reasons, including displaying it to the user in the "Where you're signed in" dialog.

By default, when puppeting another user via the admin API, the client IP address is recorded against the user who created the access token (ie, the admin user), and *not* the puppeted user.

Set this option to true to also record the IP address against the puppeted user. (This also means that the puppeted user will count as an "active" user for the purpose of monthly active user tracking – see `limit_usage_by_mau` etc above.)

Defaults to `false`.

Example configuration:
```yaml
track_puppeted_user_ips: true
```
---
### `app_service_config_files`

*(array)* A list of application service config files to use. Defaults to `[]`.

Example configuration:
```yaml
app_service_config_files:
- app_service_1.yaml
- app_service_2.yaml
```
---
### `track_appservice_user_ips`

*(boolean)* Set to true to enable tracking of application service IP addresses. Implicitly enables MAU tracking for application service users. Defaults to `false`.

Example configuration:
```yaml
track_appservice_user_ips: true
```
---
### `use_appservice_legacy_authorization`

*(boolean)* Whether to send the application service access tokens via the `access_token` query parameter per older versions of the Matrix specification. Defaults to false. Set to true to enable sending access tokens via a query parameter.

**Enabling this option is considered insecure and is not recommended.**

Defaults to `false`.

Example configuration:
```yaml
use_appservice_legacy_authorization: true
```
---
### `macaroon_secret_key`

*(string|null)* A secret which is used to sign
- access token for guest users,
- short-term login token used during SSO logins (OIDC or SAML2) and
- token used for unsubscribing from email notifications.

If none is specified, the `registration_shared_secret` is used, if one is given; otherwise, a secret key is derived from the signing key.

> ⚠️ **Warning** – Replacing an existing `macaroon_secret_key` with a new one will lead to invalidation of access tokens for all guest users. It will also break unsubscribe links in emails sent before the change. An unlucky user might encounter a broken SSO login flow and would have to start again.

Defaults to `null`.

Example configuration:
```yaml
macaroon_secret_key: <PRIVATE STRING>
```
---
### `macaroon_secret_key_path`

*(string|null)* An alternative to [`macaroon_secret_key`](#macaroon_secret_key): allows the secret key to be specified in an external file.

The file should be a plain text file, containing only the secret key. Synapse reads the secret key from the given file once at startup.

_Added in Synapse 1.121.0._

Defaults to `null`.

Example configuration:
```yaml
macaroon_secret_key_path: /path/to/secrets/file
```
---
### `form_secret`

*(string|null)* A secret which is used to calculate HMACs for form values, to stop falsification of values. Must be specified for the User Consent forms to work.

Replacing an existing `form_secret` with a new one might break the user consent page for an unlucky user and require them to reopen the page from a new link.

Defaults to `null`.

Example configuration:
```yaml
form_secret: <PRIVATE STRING>
```
---
### `form_secret_path`

*(string|null)* An alternative to [`form_secret`](#form_secret): allows the secret to be specified in an external file.

The file should be a plain text file, containing only the secret. Synapse reads the secret from the given file once at startup.

_Added in Synapse 1.126.0._

Defaults to `null`.

Example configuration:
```yaml
form_secret_path: /path/to/secrets/file
```
---
## Signing Keys

Config options relating to signing keys.

---
### `signing_key_path`

*(string|null)* Path to the signing key to sign events and federation requests with.

*New in Synapse 1.67*: If this file does not exist, Synapse will create a new signing key on startup and store it in this file.

Defaults to `null`.

Example configuration:
```yaml
signing_key_path: CONFDIR/SERVERNAME.signing.key
```
---
### `old_signing_keys`

*(object)* The keys that the server used to sign messages with but won't use to sign new messages.

It is possible to build an entry from an old `signing.key` file using the `export_signing_key` script which is provided with synapse.

If you have lost the private key file, you can ask another server you trust to tell you the public keys it has seen from your server. To fetch the keys from `matrix.org`, try something like:

```
curl https://matrix-federation.matrix.org/_matrix/key/v2/query/myserver.example.com |
  jq '.server_keys | map(.verify_keys) | add'
```

Defaults to `{}`.

Example configuration:
```yaml
old_signing_keys:
  ed25519:id:
    key: base64string
    expired_ts: 123456789123
```
---
### `key_refresh_interval`

*(duration)* How long key response published by this server is valid for. Used to set the `valid_until_ts` in `/key/v2` APIs. Determines how quickly servers will query to check which keys are still valid. Defaults to `"1d"`.

Example configuration:
```yaml
key_refresh_interval: 2d
```
---
### `trusted_key_servers`

*(array)* The trusted servers to download signing keys from.

When we need to fetch a signing key, each server is tried in parallel.

Normally, the connection to the key server is validated via TLS certificates. Additional security can be provided by configuring a `verify key`, which will make synapse check that the response is signed by that key.

This setting supersedes an older setting named `perspectives`. The old format is still supported for backwards-compatibility, but it is deprecated.

`trusted_key_servers` defaults to matrix.org, but using it will generate a warning on start-up. To suppress this warning, set `suppress_key_server_warning` to true.

If the use of a trusted key server has to be deactivated, e.g. in a private federation or for privacy reasons, this can be realised by setting an empty array (`trusted_key_servers: []`). Then Synapse will request the keys directly from the server that owns the keys. If Synapse does not get keys directly from the server, the events of this server will be rejected.

Default configuration:
```yaml
trusted_key_servers:
- server_name: matrix.org
```

Example configurations:
```yaml
trusted_key_servers:
- server_name: my_trusted_server.example.com
  verify_keys:
    ed25519:auto: abcdefghijklmnopqrstuvwxyzabcdefghijklmopqr
- server_name: my_other_trusted_server.example.com
```

```yaml
trusted_key_servers:
- server_name: matrix.org
```
---
### `suppress_key_server_warning`

*(boolean)* Set the following to true to disable the warning that is emitted when the `trusted_key_servers` include "matrix.org". See above. Defaults to `false`.

Example configuration:
```yaml
suppress_key_server_warning: true
```
---
### `key_server_signing_keys_path`

*(string|null)* The signing keys to use when acting as a trusted key server. If not specified defaults to the server signing key.

Can contain multiple keys, one per line.

Defaults to `null`.

Example configuration:
```yaml
key_server_signing_keys_path: key_server_signing_keys.key
```
---
## Single sign-on integration

The following settings can be used to make Synapse use a single sign-on provider for authentication, instead of its internal password database.

You will probably also want to set the following options to `false` to disable the regular login/registration flows:
* [`enable_registration`](#enable_registration)
* [`password_config.enabled`](#password_config)

---
### `saml2_config`

*(object)* Enable SAML2 for registration and login. Uses pysaml2. To learn more about pysaml and to find a full list options for configuring pysaml, read the docs [here](https://pysaml2.readthedocs.io/en/latest/).

At least one of `sp_config` or `config_path` must be set in this section to enable SAML login. You can either put your entire pysaml config inline using the `sp_config` option, or you can specify a path to a psyaml config file with the sub-option `config_path`.

Once SAML support is enabled, a metadata file will be exposed at `https://<server>:<port>/_synapse/client/saml2/metadata.xml`, which you may be able to use to configure your SAML IdP with. Alternatively, you can manually configure the IdP to use an ACS location of `https://<server>:<port>/_synapse/client/saml2/authn_response`.

This setting has the following sub-options:

* `idp_name` (string): A user-facing name for this identity provider, which is used to offer the user a choice of login mechanisms.

* `idp_icon` (string|null): An optional icon for this identity provider, which is presented by clients and Synapse's own IdP picker page. If given, must be an MXC URI of the format `mxc://<server-name>/<media-id>`. (An easy way to obtain such an MXC URI is to upload an image to an (unencrypted) room and then copy the URL from the source of the event.)

* `idp_brand`: An optional brand for this identity provider, allowing clients to style the login flow according to the identity provider in question. See the [spec](https://spec.matrix.org/latest/) for possible options here.

* `sp_config` (object|null): Configuration for the pysaml2 Service Provider. See pysaml2 docs for format of config. Default values will be used for the `entityid` and `service` settings, so it is not normally necessary to specify them unless you need to override them. Here are a few useful sub-options for configuring pysaml:
  * `metadata`: Point this to the IdP's metadata. You must provide either a local file via the `local` attribute or (preferably) a URL via the `remote` attribute.
  * `accepted_time_diff: 3`: Allowed clock difference in seconds between the homeserver and IdP. Defaults to 0.
  * `service`: By default, the user has to go to our login page first. If you'd like to allow IdP-initiated login, set `allow_unsolicited` to true under `sp` in the `service` section. Defaults to `null`.

* `config_path` (string|null): Specify a separate pysaml2 configuration file. Defaults to `null`.

* `saml_session_lifetime` (duration): The lifetime of a SAML session. This defines how long a user has to complete the authentication process, if `allow_unsolicited` is unset. Defaults to `"15m"`.

* `user_mapping_provider` (object): Using this option, an external module can be provided as a custom solution to mapping attributes returned from a saml provider onto a matrix user.

  This setting has the following sub-options:

  * `module` (string): The custom module's class.

  * `config` (object): Custom configuration values for the module. Use the values provided in the example if you are using the built-in user_mapping_provider, or provide your own config values for a custom class if you are using one. This section will be passed as a Python dictionary to the module's `parse_config` method. The built-in provider takes the following two options:
    * `mxid_source_attribute`: The SAML attribute (after mapping via the attribute maps) to use to derive the Matrix ID from. It is "uid" by default. Note: This used to be configured by the `saml2_config.mxid_source_attribute option`. If that is still defined, its value will be used instead.
    * `mxid_mapping`: The mapping system to use for mapping the saml attribute onto a matrix ID. Options include: `hexencode` (which maps unpermitted characters to `=xx`) and `dotreplace` (which replaces unpermitted characters with `.`). The default is `hexencode`. Note: This used to be configured by the `saml2_config.mxid_mapping option`. If that is still defined, its value will be used instead.

* `grandfathered_mxid_source_attribute` (string): In previous versions of synapse, the mapping from SAML attribute to MXID was always calculated dynamically rather than stored in a table. For backwards-compatibility, we will look for `user_ids` matching such a pattern before creating a new account. This setting controls the SAML attribute which will be used for this backwards-compatibility lookup. Typically it should be "uid", but if the attribute maps are changed, it may be necessary to change it. Defaults to `"uid"`.

* `attribute_requirements` (array): It is possible to configure Synapse to only allow logins if SAML attributes match particular values. The requirements can be listed under `attribute_requirements` as shown in the example. All of the listed attributes must match for the login to be permitted. Values can be specified in a `one_of` list to allow multiple values for an attribute.

  Options for each entry include:

  * `attribute` (string): SAML attribute for which to allow logins.

  * `value` (string): Value the SAML attribute must match.

  * `one_of` (array): List of values the SAML attribute must all match.

* `idp_entityid` (string|null): If the metadata XML contains multiple IdP entities then the `idp_entityid` option must be set to the entity to redirect users to. Most deployments only have a single IdP entity and so should omit this option. Defaults to `null`.

Example configuration:
```yaml
saml2_config:
  sp_config:
    metadata:
      local:
      - saml2/idp.xml
      remote:
      - url: https://our_idp/metadata.xml
    accepted_time_diff: 3
    service:
      sp:
        allow_unsolicited: true
    description:
    - My awesome SP
    - en
    name:
    - Test SP
    - en
    ui_info:
      display_name:
      - lang: en
        text: Display Name is the descriptive name of your service.
      description:
      - lang: en
        text: Description should be a short paragraph explaining the purpose of the
          service.
      information_url:
      - lang: en
        text: https://example.com/terms-of-service
      privacy_statement_url:
      - lang: en
        text: https://example.com/privacy-policy
      keywords:
      - lang: en
        text:
        - Matrix
        - Element
      logo:
      - lang: en
        text: https://example.com/logo.svg
        width: '200'
        height: '80'
    organization:
      name: Example com
      display_name:
      - - Example co
        - en
      url: http://example.com
    contact_person:
    - given_name: Bob
      sur_name: the Sysadmin
      email_address:
      - admin@example.com
      contact_type: technical
  saml_session_lifetime: 5m
  user_mapping_provider:
    config:
      mxid_source_attribute: displayName
      mxid_mapping: dotreplace
  grandfathered_mxid_source_attribute: upn
  attribute_requirements:
  - attribute: userGroup
    value: staff
  - attribute: department
    one_of:
    - sales
    - admins
  idp_entityid: https://our_idp/entityid
```
---
### `oidc_providers`

*(array)* List of OpenID Connect (OIDC) / OAuth 2.0 identity providers, for registration and login. See [here](../../openid.md) for information on how to configure these options.

For backwards compatibility, it is also possible to configure a single OIDC provider via an `oidc_config` setting. This is now deprecated and admins are advised to migrate to the `oidc_providers` format. (When doing that migration, use `oidc` for the `idp_id` to ensure that existing users continue to be recognised.)

It is possible to configure Synapse to only allow logins if certain attributes match particular values in the OIDC userinfo. The requirements can be listed under `attribute_requirements` as shown here:
```yaml
attribute_requirements:
  - attribute: family_name
    one_of: ["Stephensson", "Smith"]
  - attribute: groups
    value: "admin"
  # If `value` or `one_of` are not specified, the attribute only needs
  # to exist, regardless of value.
  - attribute: picture
```

`attribute` is a required field, while `value` and `one_of` are optional.

All of the listed attributes must match for the login to be permitted. Additional attributes can be added to userinfo by expanding the `scopes` section of the OIDC config to retrieve additional information from the OIDC provider.

If the OIDC claim is a list, then the attribute must match any value in the list. Otherwise, it must exactly match the value of the claim. Using the example above, the `family_name` claim MUST be either "Stephensson" or "Smith", but the `groups` claim MUST contain "admin".

Defaults to `[]`.

Options for each entry include:

* `idp_id` (string): A unique identifier for this identity provider. Used internally by Synapse; should be a single word such as "github". Note that, if this is changed, users authenticating via that provider will no longer be recognised as the same user! (Use "oidc" here if you are migrating from an old `oidc_config` configuration.)

* `idp_name` (string): A user-facing name for this identity provider, which is used to offer the user a choice of login mechanisms.

* `idp_icon` (string): An optional icon for this identity provider, which is presented by clients and Synapse's own IdP picker page. If given, must be an MXC URI of the format `mxc://<server-name>/<media-id>`. (An easy way to obtain such an MXC URI is to upload an image to an (unencrypted) room and then copy the URL from the source of the event.)

* `idp_brand` (string): An optional brand for this identity provider, allowing clients to style the login flow according to the identity provider in question. See the [spec](https://spec.matrix.org/latest/) for possible options here.

* `discover` (boolean): Set to false to disable the use of the OIDC discovery mechanism to discover endpoints. Defaults to true.

* `issuer` (string): Required. The OIDC issuer. Used to validate tokens and (if discovery is enabled) to discover the provider's endpoints.

* `client_id` (string): Required. OAuth2 client id to use.

* `client_secret` (string|null): OAuth2 client secret to use. May be omitted if `client_secret_jwt_key` is given, or if `client_auth_method` is `none`. Must be omitted if `client_secret_path` is specified.

* `client_secret_path` (string|null): Path to the OAuth2 client secret to use. With that it's not necessary to leak secrets into the config file itself. Mutually exclusive with `client_secret`. Can be omitted if `client_secret_jwt_key` is specified.

  *Added in Synapse 1.91.0.*

* `client_secret_jwt_key` (object|null): Alternative to client_secret: details of a key used to create a JSON Web Token to be used as an OAuth2 client secret.

  This setting has the following sub-options:

  * `key` (string|null): A pem-encoded signing key. Must be a suitable key for the algorithm specified. Required unless `key_file` is given.

  * `key_file` (string|null): Path to the file containing a pem-encoded signing key. Required unless `key` is given.

  * `jwt_header` (object): Dictionary giving properties to include in the JWT header. Must include the key `alg`.

    This setting has the following sub-options:

    * `alg` (string): Algorithm used to sign the JWT, such as ES256, using the JWA identifiers in RFC7518.

  * `jwt_payload` (object): Optional dictionary giving properties to include in the JWT payload. Normally this should include an `iss` key.

* `client_auth_method` (string|null): Auth method to use when exchanging the token. Valid values are `client_secret_basic` (default), `client_secret_post` and `none`.

* `pkce_method` (string|null): Whether to use proof key for code exchange when requesting and exchanging the token. Valid values are: `auto`, `always`, or `never`. Defaults to `auto`, which uses PKCE if supported during metadata discovery. Set to `always` to force enable PKCE or `never` to force disable PKCE.

* `id_token_signing_alg_values_supported` (array): List of the JWS signing algorithms (`alg` values) that are supported for signing the `id_token`.

  This is *not* required if `discovery` is disabled. We default to supporting `RS256` in the downstream usage if no algorithms are configured here or in the discovery document.

  According to the spec, the algorithm `"RS256"` MUST be included. The absolute rigid approach would be to reject this provider as non-compliant if it's not included but we simply allow whatever and see what happens (you're the one that configured the value and cooperating with the identity provider).

  The `alg` value `"none"` MAY be supported but can only be used if the Authorization Endpoint does not include `id_token` in the `response_type` (ex. `/authorize?response_type=code` where `none` can apply, `/authorize?response_type=code%20id_token` where `none` can't apply) (such as when using the Authorization Code Flow).

* `scopes` (array|null): List of scopes to request. This should normally include the "openid" scope. Defaults to `["openid"]`.

* `authorization_endpoint` (string): The OAuth2 authorization endpoint. Required if provider discovery is disabled.

* `token_endpoint` (string): The OAuth2 token endpoint. Required if provider discovery is disabled.

* `userinfo_endpoint` (string): The OIDC userinfo endpoint. Required if discovery is disabled and the "openid" scope is not requested.

* `jwks_uri` (string): URI where to fetch the JWKS. Required if discovery is disabled and the "openid" scope is used.

* `skip_verification` (boolean): Set to `true` to skip metadata verification. Use this if you are connecting to a provider that is not OpenID Connect compliant. Defaults to false. Avoid this in production.

* `user_profile_method` (string|null): Whether to fetch the user profile from the userinfo endpoint, or to rely on the data returned in the id_token from the `token_endpoint`. Valid values are: `auto` or `userinfo_endpoint`. Defaults to `auto`, which uses the userinfo endpoint if `openid` is not included in `scopes`. Set to `userinfo_endpoint` to always use the userinfo endpoint.

* `redirect_uri` (string|null): An optional string, that if set will override the `redirect_uri` parameter sent in the requests to the authorization and token endpoints. Useful if you want to redirect the client to another endpoint as part of the OIDC login. Be aware that the client must then call Synapse's OIDC callback URL (`<public_baseurl>/_synapse/client/oidc/callback`) manually afterwards. Must be a valid URL including scheme and path.

* `additional_authorization_parameters` (object): String to string dictionary that will be passed as additional parameters to the authorization grant URL.

* `passthrough_authorization_parameters` (array): List of parameters that will be passed through from the redirect endpoint to the authorization grant URL.

* `allow_existing_users` (boolean): Set to true to allow a user logging in via OIDC to match a pre-existing account instead of failing. This could be used if switching from password logins to OIDC. Defaults to false.

* `enable_registration` (boolean): Set to `false` to disable automatic registration of new users. This allows the OIDC SSO flow to be limited to sign in only, rather than automatically registering users that have a valid SSO login but do not have a pre-registered account. Defaults to true.

* `user_mapping_provider` (object): Configuration for how attributes returned from a OIDC provider are mapped onto a matrix user.

  When rendering, the Jinja2 templates are given a `user` variable, which is set to the claims returned by the UserInfo Endpoint and/or in the ID Token.

  This setting has the following sub-options:

  * `module` (string): The class name of a custom mapping module. Default is `synapse.handlers.oidc.JinjaOidcMappingProvider`. See [OpenID Mapping Providers](../../sso_mapping_providers.md#openid-mapping-providers) for information on implementing a custom mapping provider.

  * `config` (object): Configuration for the mapping provider module. This section will be passed as a Python dictionary to the user mapping provider module's `parse_config` method.

    For the default provider, the following settings are available:

    * `subject_template`: Jinja2 template for a unique identifier for the user. Defaults to `{{ user.sub }}`, which OpenID Connect compliant providers should provide.

      This replaces and overrides `subject_claim`.

    * `subject_claim`: name of the claim containing a unique identifier for the user. Defaults to `sub`, which OpenID Connect compliant providers should provide.

      *Deprecated in Synapse v1.75.0.*

    * `picture_template`: Jinja2 template for an url for the user's profile picture. Defaults to `{{ user.picture }}`, which OpenID Connect compliant providers should provide and has to refer to a direct image file such as PNG, JPEG, or GIF image file.

      This replaces and overrides `picture_claim`.

      Currently only supported in monolithic (single-process) server configurations where the media repository runs within the Synapse process.

    * `picture_claim`: name of the claim containing an url for the user's profile picture. Defaults to "picture", which OpenID Connect compliant providers should provide and has to refer to a direct image file such as PNG, JPEG, or GIF image file.

      Currently only supported in monolithic (single-process) server configurations where the media repository runs within the Synapse process.

      *Deprecated in Synapse v1.75.0.*

    * `localpart_template`: Jinja2 template for the localpart of the MXID. If this is not set, the user will be prompted to choose their own username (see the documentation for the `sso_auth_account_details.html` template). This template can use the `localpart_from_email` filter.

    * `confirm_localpart`: Whether to prompt the user to validate (or change) the generated localpart (see the documentation for the "sso_auth_account_details.html" template), instead of registering the account right away.

    * `display_name_template`: Jinja2 template for the display name to set on first login. If unset, no displayname will be set.

    * `email_template`: Jinja2 template for the email address of the user. If unset, no email address will be added to the account.

    * `extra_attributes`: a map of Jinja2 templates for extra attributes to send back to the client during login. Note that these are non-standard and clients will ignore them without modifications.

* `backchannel_logout_enabled` (boolean): Set to `true` to process OIDC Back-Channel Logout notifications. Those notifications are expected to be received on `/_synapse/client/oidc/backchannel_logout`. Defaults to `false`.

* `backchannel_logout_ignore_sub` (boolean): By default, the OIDC Back-Channel Logout feature checks that the `sub` claim matches the subject claim received during login. This check can be disabled by setting this to `true`. Defaults to `false`.

  You might want to disable this if the `subject_claim` returned by the mapping provider is not `sub`.

Example configuration:
```yaml
oidc_providers:
- idp_id: my_idp
  idp_name: My OpenID provider
  idp_icon: mxc://example.com/mediaid
  discover: false
  issuer: https://accounts.example.com/
  client_id: provided-by-your-issuer
  client_secret: provided-by-your-issuer
  client_auth_method: client_secret_post
  scopes:
  - openid
  - profile
  authorization_endpoint: https://accounts.example.com/oauth2/auth
  token_endpoint: https://accounts.example.com/oauth2/token
  userinfo_endpoint: https://accounts.example.com/userinfo
  jwks_uri: https://accounts.example.com/.well-known/jwks.json
  additional_authorization_parameters:
    acr_values: 2fa
  passthrough_authorization_parameters:
  - login_hint
  skip_verification: true
  enable_registration: true
  user_mapping_provider:
    config:
      subject_claim: id
      localpart_template: '{{ user.login }}'
      display_name_template: '{{ user.name }}'
      email_template: '{{ user.email }}'
  attribute_requirements:
  - attribute: userGroup
    value: synapseUsers
```
---
### `cas_config`

*(object)* Enable Central Authentication Service (CAS) for registration and login.

This setting has the following sub-options:

* `enabled` (boolean): Set this to true to enable authorization against a CAS server. Defaults to `false`.

* `idp_name` (string): A user-facing name for this identity provider, which is used to offer the user a choice of login mechanisms.

* `idp_icon` (string|null): An optional icon for this identity provider, which is presented by clients and Synapse's own IdP picker page. If given, must be an MXC URI of the format `mxc://<server-name>/<media-id>`. (An easy way to obtain such an MXC URI is to upload an image to an (unencrypted) room and then copy the URL from the source of the event.) Defaults to `null`.

* `idp_brand` (string|null): An optional brand for this identity provider, allowing clients to style the login flow according to the identity provider in question. See the [spec](https://spec.matrix.org/latest/) for possible options here. Defaults to `null`.

* `server_url` (string): The URL of the CAS authorization endpoint.

* `protocol_version` (integer|null): The CAS protocol version. (Version 3 is required if you want to use `required_attributes`). Defaults to `null`.

* `displayname_attribute` (string|null): The attribute of the CAS response to use as the display name. If no name is given here, no displayname will be set. Defaults to `null`.

* `required_attributes` (object): It is possible to configure Synapse to only allow logins if CAS attributes match particular values. All of the keys given below must exist and the values must match the given value. Alternately if the given value is `None` then any value is allowed (the attribute just must exist). All of the listed attributes must match for the login to be permitted. Defaults to `{}`.

* `enable_registration` (boolean): Set to `false` to disable automatic registration of new users. This allows the CAS SSO flow to be limited to sign in only, rather than automatically registering users that have a valid SSO login but do not have a pre-registered account. Defaults to `true`.

* `allow_numeric_ids` (boolean): Set to `true` allow numeric user IDs. This allows CAS SSO flow to provide user IDs composed of numbers only. These identifiers will be prefixed by the letter "u" by default. The prefix can be configured using the `numeric_ids_prefix` option. Be careful to choose the prefix correctly to avoid any possible conflicts (e.g. user 1234 becomes u1234 when a user u1234 already exists). Defaults to `false`.

* `numeric_ids_prefix` (string): The prefix you wish to add in front of a numeric user ID when the `allow_numeric_ids` option is set to `true`. Only alphanumeric characters are allowed.

  *Added in Synapse 1.93.0.*

  Defaults to `"u"`.

Example configuration:
```yaml
cas_config:
  enabled: true
  server_url: https://cas-server.com
  protocol_version: 3
  displayname_attribute: name
  required_attributes:
    userGroup: staff
    department: None
  enable_registration: true
  allow_numeric_ids: true
  numeric_ids_prefix: numericuser
```
---
### `sso`

*(object)* Additional settings to use with single-sign on systems such as OpenID Connect, SAML2 and CAS.

Server admins can configure custom templates for pages related to SSO. See [here](../../templates.md) for more information.

This setting has the following sub-options:

* `client_whitelist` (array|null): A list of client URLs which are whitelisted so that the user does not have to confirm giving access to their account to the URL. Any client whose URL starts with an entry in the following list will not be subject to an additional confirmation step after the SSO login is completed.

  WARNING: An entry such as "https://my.client" is insecure, because it will also match "https://my.client.evil.site", exposing your users to phishing attacks from evil.site. To avoid this, include a slash after the hostname: "https://my.client/".

  The login fallback page (used by clients that don't natively support the required login flows) is whitelisted in addition to any URLs in this list. By default, this list contains only the login fallback page.

  Defaults to `null`.

* `update_profile_information` (boolean): Use this setting to keep a user's profile fields in sync with information from the identity provider. Fields are checked on every SSO login, and are updated if necessary. Note that enabling this option will override user profile information, regardless of whether users have opted-out of syncing that information when first signing in. Fields that will be synced:
    * displayname
    * picture - only if Synapse media repository is running in the main
       process (i.e. not workerized) and media is stored locally Defaults to `false`.

Example configuration:
```yaml
sso:
  client_whitelist:
  - https://riot.im/develop
  - https://my.custom.client/
  update_profile_information: true
```
---
### `jwt_config`

*(object)* JSON web token integration. The following settings can be used to make Synapse JSON web tokens for authentication, instead of its internal password database.

Each JSON Web Token needs to contain a "sub" (subject) claim, which is used as the localpart of the mxid.

Additionally, the expiration time ("exp"), not before time ("nbf"), and issued at ("iat") claims are validated if present.

Note that this is a non-standard login type and client support is expected to be non-existent.

See [here](../../jwt.md) for more.

This setting has the following sub-options:

* `enabled` (boolean): Set to true to enable authorization using JSON web tokens. Defaults to `false`.

* `secret` (string): This is either the private shared secret or the public key used to decode the contents of the JSON web token. Required if `enabled` is set to true.

* `algorithm` (string): The algorithm used to sign (or HMAC) the JSON web token. Supported algorithms are listed [here (section JWS)](https://docs.authlib.org/en/latest/specs/rfc7518.html). Required if `enabled` is set to true.

* `subject_claim` (string|null): Name of the claim containing a unique identifier for the user. Defaults to `"sub"`.

* `display_name_claim` (string|null): Name of the claim containing the display name for the user. If provided, the display name will be set to the value of this claim upon first login. Defaults to `null`.

* `issuer` (string|null): The issuer to validate the "iss" claim against. If provided the "iss" claim will be required and validated for all JSON web tokens. Defaults to `null`.

* `audiences` (array|null): A list of audiences to validate the "aud" claim against. If provided the "aud" claim will be required and validated for all JSON web tokens. Note that if the "aud" claim is included in a JSON web token then validation will fail without configuring audiences. Defaults to `null`.

Example configuration:
```yaml
jwt_config:
  enabled: true
  secret: provided-by-your-issuer
  algorithm: provided-by-your-issuer
  subject_claim: name_of_claim
  display_name_claim: name_of_claim
  issuer: provided-by-your-issuer
  audiences:
  - provided-by-your-issuer
```
---
### `password_config`

*(object)* Use this setting to enable password-based logins.

This setting has the following sub-options:

* `enabled` (boolean|string): Set to false to disable password authentication. Set to `only_for_reauth` to allow users with existing passwords to use them to reauthenticate (not log in), whilst preventing new users from setting passwords. Defaults to `true`.

* `localdb_enabled` (boolean): Set to false to disable authentication against the local password database. This is ignored if `enabled` is false, and is only useful if you have other `password_providers`. Defaults to `true`.

* `pepper` (string|null): A secret random string that will be appended to user's passwords before they are hashed. This improves the security of short passwords. DO NOT CHANGE THIS AFTER INITIAL SETUP! Defaults to `null`.

* `policy` (object): Define and enforce a password policy, such as minimum lengths for passwords, etc. This is an implementation of MSC2000.

  This setting has the following sub-options:

  * `enabled` (boolean): Set to true to enable. Defaults to `false`.

  * `minimum_length` (integer): Minimum accepted length for a password. Defaults to `0`.

  * `require_digit` (boolean): Whether a password must contain at least one digit. Defaults to `false`.

  * `require_symbol` (boolean): Whether a password must contain at least one symbol. A symbol is any character that's not a number or a letter. Defaults to `false`.

  * `require_lowercase` (boolean): Whether a password must contain at least one lowercase letter. Defaults to `false`.

  * `require_uppercase` (boolean): Whether a password must contain at least one uppercase letter. Defaults to `false`.

Example configuration:
```yaml
password_config:
  enabled: false
  localdb_enabled: false
  pepper: EVEN_MORE_SECRET
  policy:
    enabled: true
    minimum_length: 15
    require_digit: true
    require_symbol: true
    require_lowercase: true
    require_uppercase: true
```
---
## Push

Configuration settings related to push notifications.

---
### `push`

*(object)* This setting defines options for push notifications.

This setting has the following sub-options:

* `enabled` (boolean): Enables or disables push notification calculation. Note, disabling this will also stop unread counts being calculated for rooms. This mode of operation is intended for homeservers which may only have bots or appservice users connected, or are otherwise not interested in push/unread counters. Defaults to `true`.

* `include_content` (boolean): Clients requesting push notifications can either have the body of the message sent in the notification poke along with other details like the sender, or just the event ID and room ID (`event_id_only`). If clients choose to have the body sent, this option controls whether the notification request includes the content of the event (other details like the sender are still included). If `event_id_only` is enabled, it has no effect. For modern Android devices the notification content will still appear because it is loaded by the app. iPhone, however will send a notification saying only that a message arrived and who it came from. Set to false to only include the event ID and room ID in push notification payloads. Defaults to `true`.

* `group_unread_count_by_room` (boolean): When a push notification is received, an unread count is also sent. This number can either be calculated as the number of unread messages for the user, or the number of *rooms* the user has unread messages in. If true, push clients will see the number of rooms with unread messages in them. Set to false to instead send the number of unread messages. Defaults to `true`.

* `jitter_delay` (duration): Delays push notifications by a random amount up to the given duration. Useful for mitigating timing attacks. Optional.

  _Added in Synapse 1.84.0._

  Defaults to `"0s"`.

Example configuration:
```yaml
push:
  enabled: true
  include_content: false
  group_unread_count_by_room: false
  jitter_delay: 10s
```
---
### `push_rules`

*(object)* Options for push rules

This setting has the following sub-options:

* `limits` (object): Limits on the size of push rules that users can have

  This setting has the following sub-options:

  * `rule_count` (integer): This is the total number of push rules that each user can have. Power users may expect to have one push rule per room. Defaults to `10000`.

  * `rule_id_length` (integer): This is the maximum length of a push rule ID, in bytes. Push rule IDs need to be allowed to be at least as long as a room ID (which are [limited to 255 bytes per specification](https://spec.matrix.org/v1.19/appendices/#room-ids))
    It's recommended to leave this option as it is. We expect to remove this option if/when the specification standardises on a limit. Defaults to `300`.

  * `rule_size` (integer): This is the maximum size of a push rule's body, in bytes.
    The exact mechanism for calculating this size is currently an implementation detail, subject to change. This limit should be treated as a coarse sanity limit rather than something to fine-tune.
    It's recommended to leave this option as it is. We expect to remove this option if/when the specification standardises on a limit and a mechanism for calculating it. Defaults to `1024`.
---
## Rooms

Config options relating to rooms.

---
### `encryption_enabled_by_default_for_room_type`

*(string)* Controls whether locally-created rooms should be end-to-end encrypted by default.

Possible options are "all", "invite", and "off". They are defined as:

* "all": any locally-created room
* "invite": any room created with the `private_chat` or `trusted_private_chat` room creation presets
* "off": this option will take no effect

Note that this option will only affect rooms created after it is set. It will also not affect rooms created by other servers.

Defaults to `"off"`.

Example configuration:
```yaml
encryption_enabled_by_default_for_room_type: invite
```
---
### `user_directory`

*(object)* This setting defines options related to the user directory.

This setting has the following sub-options:

* `enabled` (boolean): Defines whether users can search the user directory. If `false` then empty responses are returned to all queries.

  *Warning: While the homeserver may determine which subset of users are searched, the Matrix specification requires homeservers to include (at minimum) users visible in public rooms and users sharing a room with the requester. Using `false` improves performance but violates this requirement.*

  Defaults to `true`.

* `search_all_users` (boolean): Defines whether to search all users visible to your homeserver at the time the search is performed. If set to true, will return all users known to the homeserver matching the search query. If false, search results will only contain users visible in public rooms and users sharing a room with the requester.

  NB. If you set this to true, and the last time the user_directory search indexes were (re)built was before Synapse 1.44, you'll have to rebuild the indexes in order to search through all known users.

  These indexes are built the first time Synapse starts; admins can manually trigger a rebuild via the API following the instructions [for running background updates](../administration/admin_api/background_updates.md#run), set to true to return search results containing all known users, even if that user does not share a room with the requester.

  Defaults to `false`.

* `prefer_local_users` (boolean): Defines whether to prefer local users in search query results. If set to true, local users are more likely to appear above remote users when searching the user directory. Defaults to `false`.

* `exclude_remote_users` (boolean): If set to true, the search will only return local users. Defaults to `false`.

* `show_locked_users` (boolean): Defines whether to show locked users in search query results. Defaults to `false`.

Example configuration:
```yaml
user_directory:
  enabled: false
  search_all_users: true
  prefer_local_users: true
  exclude_remote_users: false
  show_locked_users: true
```
---
### `user_consent`

*(object)* For detailed instructions on user consent configuration, see [here](../../consent_tracking.md).

Parts of this section are required if enabling the `consent` resource under [`listeners`](#listeners), in particular `template_dir` and `version`.

This setting has the following sub-options:

* `template_dir` (string): Gives the location of the templates for the HTML forms. This directory should contain one subdirectory per language (eg, `en`, `fr`), and each language directory should contain the policy document (named as <version>.html) and a success page (success.html).

* `version` (number): Specifies the "current" version of the policy document. It defines the version to be served by the consent resource if there is no `v` parameter.

* `server_notice_content` (object): If enabled, will send a user a "Server Notice" asking them to consent to the privacy policy. The [`server_notices` section](#server_notices) must also be configured for this to work. Notices will *not* be sent to guest users unless `send_server_notice_to_guests` is set to true.

  This setting has the following sub-options:

  * `msgtype` (string): Message type of the notice event.

  * `body` (string): Message template for the server notice event body.

* `send_server_notice_to_guests` (boolean): Send server notices to guest users, too. Defaults to `false`.

* `block_events_error` (string|null): If set, will block any attempts to send events until the user consents to the privacy policy. The value of the setting is used as the text of the error. Defaults to `null`.

* `require_at_registration` (boolean): If enabled, will add a step to the registration process, similar to how captcha works. Users will be required to accept the policy before their account is created.

* `policy_name` (string): Human-readable name of the privacy policy. Defaults to `"Privacy Policy"`.

Example configuration:
```yaml
user_consent:
  template_dir: res/templates/privacy
  version: 1.0
  server_notice_content:
    msgtype: m.text
    body: To continue using this homeserver you must review and agree to the terms
      and conditions at %(consent_uri)s
  send_server_notice_to_guests: true
  block_events_error: To continue using this homeserver you must review and agree
    to the terms and conditions at %(consent_uri)s
  require_at_registration: false
  policy_name: Privacy Policy
```
---
### `stats`

*(object)* Settings for local room and user statistics collection. See [here](../../room_and_user_statistics.md) for more.

This setting has the following sub-options:

* `enabled` (boolean): Set to false to disable room and user statistics. Note that doing so may cause certain features (such as the room directory) not to work correctly. Defaults to `true`.

Example configuration:
```yaml
stats:
  enabled: false
```
---
### `server_notices`

*(object)* Use this setting to enable a room which can be used to send notices from the server to users. It is a special room which users cannot leave; notices in the room come from a special "notices" user id.

If you use this setting, you *must* define the `system_mxid_localpart` sub-setting, which defines the id of the user which will be used to send the notices.

Note that the name, topic and avatar of existing server notice rooms will only be updated when a new notice event is sent.

This setting has the following sub-options:

* `system_mxid_display_name` (string): Display name of the "notices" user. Defaults to `"Notices"`.

* `system_mxid_avatar_url` (string|null): Avatar for the "notices" user. Defaults to `null`.

* `room_name` (string): Room name of the server notices room. Defaults to `"Server Notices"`.

* `room_avatar_url` (string|null): Room avatar to use for server notice rooms. If set to the empty string `""`, notice rooms will not be given an avatar.

  _Added in Synapse 1.99.0._

  Defaults to `null`.

* `room_topic` (string|null): Topic to use for server notice rooms. If set to the empty string `""`, notice rooms will not be given a topic. Defaults to the empty string.

  _Added in Synapse 1.99.0._

  Defaults to `null`.

* `auto_join` (boolean): If true, the user will be automatically joined to the room instead of being invited.

  _Added in Synapse 1.98.0._

  Defaults to `false`.

Example configuration:
```yaml
server_notices:
  system_mxid_localpart: notices
  system_mxid_display_name: Server Notices
  system_mxid_avatar_url: mxc://example.com/oumMVlgDnLYFaPVkExemNVVZ
  room_name: Server Notices
  room_avatar_url: mxc://example.com/oumMVlgDnLYFaPVkExemNVVZ
  room_topic: Room used by your server admin to notice you of important information
  auto_join: true
```
---
### `enable_room_list_search`

*(boolean)* Set to false to disable searching the public room list. When disabled blocks searching local and remote room lists for local and remote users by always returning an empty list for all queries. Defaults to `true`.

Example configuration:
```yaml
enable_room_list_search: false
```
---
### `alias_creation_rules`

*(array|null)* The `alias_creation_rules` option allows server admins to prevent unwanted alias creation on this server.

This setting is an optional list of 0 or more rules. By default, no list is provided, meaning that all alias creations are permitted.

Otherwise, requests to create aliases are matched against each rule in order. The first rule that matches decides if the request is allowed or denied. If no rule matches, the request is denied. In particular, this means that configuring an empty list of rules will deny every alias creation request.

Each of the glob patterns is optional, defaulting to `*` ("match anything"). Note that the patterns match against fully qualified IDs, e.g. against `@alice:example.com`, `#room:example.com` and `!abcdefghijk:example.com` instead of `alice`, `room` and `abcedgghijk`.

Each rule is a YAML object containing four fields, each of which is an optional string

Defaults to `null`.

Options for each entry include:

* `user_id` (string|null): Glob pattern that matches against the creator of the alias.

* `alias` (string|null): Glob pattern that matches against the alias being created.

* `room_id` (string|null): Glob pattern that matches against the room ID the alias is being pointed at.

* `action` (string): Either `allow` or `deny`. What to do with the request if the rule matches. Defaults to `allow`.

Example configurations:
```yaml
alias_creation_rules: null
```

```yaml
alias_creation_rules:
- action: allow
```

```yaml
alias_creation_rules: []
```

```yaml
alias_creation_rules:
- action: deny
```

```yaml
alias_creation_rules:
- user_id: '@bad_user:example.com'
  action: deny
- action: allow
```

```yaml
alias_creation_rules:
- room_id: '!forbiddenRoom:example.com'
  action: deny
- action: allow
```
---
### `room_list_publication_rules`

*(array|null)* The `room_list_publication_rules` option allows server admins to prevent unwanted entries from being published in the public room list.

The format of this option is the same as that for [`alias_creation_rules`](#alias_creation_rules): an optional list of 0 or more rules. By default, no list is provided, meaning that no one may publish to the room list (except server admins).

Otherwise, requests to publish a room are matched against each rule in order. The first rule that matches decides if the request is allowed or denied. If no rule matches, the request is denied. In particular, this means that configuring an empty list of rules will deny every alias creation request.

Requests to create a public (public as in published to the room directory) room which violates the configured rules will result in the room being created but not published to the room directory.

Each of the glob patterns is optional, defaulting to `*` ("match anything"). Note that the patterns match against fully qualified IDs, e.g. against `@alice:example.com`, `#room:example.com` and `!abcdefghijk:example.com` instead of `alice`, `room` and `abcedgghijk`.

Each rule is a YAML object containing four fields, each of which is an optional string.

_Changed in Synapse 1.126.0: The default was changed to deny publishing to the room list by default_

Defaults to `null`.

Options for each entry include:

* `user_id` (string|null): Glob pattern that matches against the user publishing the room.

* `alias` (string|null): Glob pattern that matches against one of published room's aliases.
  - If the room has no aliases, the alias match fails unless `alias` is unspecified or `*`.
  - If the room has exactly one alias, the alias match succeeds if the `alias` pattern matches that alias.
  - If the room has two or more aliases, the alias match succeeds if the pattern matches at least one of the aliases.

* `room_id` (string|null): Glob pattern that matches against the room ID of the room being published.

* `action` (string): Either `allow` or `deny`. What to do with the request if the rule matches. Defaults to `allow`.

Example configurations:
```yaml
room_list_publication_rules: null
```

```yaml
room_list_publication_rules:
- action: deny
```

```yaml
room_list_publication_rules: []
```

```yaml
room_list_publication_rules:
- action: allow
```

```yaml
room_list_publication_rules:
- user_id: '@bad_user:example.com'
  action: deny
- action: allow
```

```yaml
room_list_publication_rules:
- room_id: '!forbiddenRoom:example.com'
  action: deny
- action: allow
```

```yaml
room_list_publication_rules:
- alias: '#*potato*:example.com'
  action: deny
- action: allow
```
---
### `default_power_level_content_override`

*(object)* The `default_power_level_content_override` option controls the default power levels for rooms.

Useful if you know that your users need special permissions in rooms that they create (e.g. to send particular types of state events without needing an elevated power level).  This takes the same shape as the `power_level_content_override` parameter in the /createRoom API, but is applied before that parameter.

Note that each key provided inside a preset (for example `events` in the example below) will overwrite all existing defaults inside that key. So in Example #1, newly-created private_chat rooms will have no rules for any event types except `com.example.foo`.

The default power levels for each preset are:

```yaml
"m.room.name": 50
"m.room.power_levels": 100
"m.room.history_visibility": 100
"m.room.canonical_alias": 50
"m.room.avatar": 50
"m.room.tombstone": 100 (150 if MSC4289 is used)
"m.room.server_acl": 100
"m.room.encryption": 100
```

In Example #2 the default power-levels for a preset are maintained, but the power level for a new key is set.

Defaults to `{}`.

Example configurations:
```yaml
default_power_level_content_override:
  private_chat:
    events:
      com.example.foo: 0
  trusted_private_chat: null
  public_chat: null
```

```yaml
default_power_level_content_override:
  private_chat:
    events:
      com.example.foo: 0
      m.room.name: 50
      m.room.power_levels: 100
      m.room.history_visibility: 100
      m.room.canonical_alias: 50
      m.room.avatar: 50
      m.room.tombstone: 100
      m.room.server_acl: 100
      m.room.encryption: 100
  trusted_private_chat: null
  public_chat: null
```
---
### `forget_rooms_on_leave`

*(boolean)* Set to true to automatically forget rooms for users when they leave them, either normally or via a kick or ban. Defaults to `false`.

Example configuration:
```yaml
forget_rooms_on_leave: true
```
---
### `exclude_rooms_from_sync`

*(array)* A list of rooms to exclude from sync responses. This is useful for server administrators wishing to group users into a room without these users being able to see it from their client. Defaults to `[]`.

Example configuration:
```yaml
exclude_rooms_from_sync:
- '!foo:example.com'
```
---
### `exclude_rooms_from_presence`

*(array)* A list of rooms to exclude from presence updates. Presence will not be routed between two users solely because they share one of these rooms. Users who also share a non-excluded room continue to exchange presence as normal. Defaults to `[]`.

Example configuration:
```yaml
exclude_rooms_from_presence:
- '!foo:example.com'
```
---
## Opentracing

Configuration options related to Opentracing support.

---
### `opentracing`

*(object)* These settings enable and configure opentracing, which implements distributed tracing. This allows you to observe the causal chains of events across servers including requests, key lookups etc., across any server running synapse or any other services which support opentracing (specifically those implemented with Jaeger).

This setting has the following sub-options:

* `enabled` (boolean): Whether tracing is enabled. Set to true to enable. Defaults to `false`.

* `homeserver_whitelist` (array): The list of homeservers we wish to send and receive span contexts and span baggage. See [here](../../opentracing.md) for more. This is a list of regexes which are matched against the `server_name` of the homeserver. If the list is empty, no servers are matched. Defaults to `[]`.

* `force_tracing_for_users` (array): A list of the matrix IDs of users whose requests will always be traced, even if the tracing system would otherwise drop the traces due to probabilistic sampling. Defaults to `[]`.

* `jaeger_config` (object): Jaeger can be configured to sample traces at different rates. All configuration options provided by Jaeger can be set here. Jaeger's configuration is mostly related to trace sampling which is documented [here](https://www.jaegertracing.io/docs/latest/sampling/). Defaults to `{}`.

Example configuration:
```yaml
opentracing:
  enabled: true
  homeserver_whitelist:
  - .*
  force_tracing_for_users:
  - '@user1:server_name'
  - '@user2:server_name'
  jaeger_config:
    sampler:
      type: const
      param: 1
    logging: false
```
---
## Coordinating workers

Configuration options related to workers which belong in the main config file (usually called `homeserver.yaml`). A Synapse deployment can scale horizontally by running multiple Synapse processes called _workers_. Incoming requests are distributed between workers to handle higher loads. Some workers are privileged and can accept requests from other workers.

As a result, the worker configuration is divided into two parts.

1. The first part (in this section of the manual) defines which shardable tasks are delegated to privileged workers. This allows unprivileged workers to make requests to a privileged worker to act on their behalf.
2. [The second part](#individual-worker-configuration) controls the behaviour of individual workers in isolation.

For guidance on setting up workers, see the [worker documentation](../../workers.md).

---
### `worker_replication_secret`

*(string|null)* A shared secret used by the replication APIs on the main process to authenticate HTTP requests from workers.

If unset or null, traffic between the workers and the main process is not authenticated.

Replacing an existing `worker_replication_secret` with a new one will break communication with all workers that have not yet updated their secret.

Defaults to `null`.

Example configuration:
```yaml
worker_replication_secret: secret_secret
```
---
### `worker_replication_secret_path`

*(string|null)* An alternative to [`worker_replication_secret`](#worker_replication_secret): allows the secret to be specified in an external file.

The file should be a plain text file, containing only the secret. Synapse reads the secret from the given file once at startup.

_Added in Synapse 1.126.0._

Defaults to `null`.

Example configuration:
```yaml
worker_replication_secret_path: /path/to/secrets/file
```
---
### `start_pushers`

*(boolean)* Unnecessary to set if using [`pusher_instances`](#pusher_instances) with [`generic_workers`](../../workers.md#synapseappgeneric_worker).

Controls sending of push notifications on the main process. Set to `false` if using a [pusher worker](../../workers.md#synapseapppusher).

Defaults to `true`.

Example configuration:
```yaml
start_pushers: false
```
---
### `pusher_instances`

*(array)* It is possible to scale the processes that handle sending push notifications to [sygnal](https://github.com/matrix-org/sygnal) and email by running a [`generic_worker`](../../workers.md#synapseappgeneric_worker) and adding it's [`worker_name`](#worker_name) to a `pusher_instances` map. Doing so will remove handling of this function from the main process. Multiple workers can be added to this map, in which case the work is balanced across them. Ensure the main process and all pusher workers are restarted after changing this option. Defaults to `[]`.

Example configurations:
```yaml
pusher_instances:
- pusher_worker1
```

```yaml
pusher_instances:
- pusher_worker1
- pusher_worker2
```
---
### `send_federation`

*(boolean)* Unnecessary to set if using [`federation_sender_instances`](#federation_sender_instances) with [`generic_workers`](../../workers.md#synapseappgeneric_worker).

Controls sending of outbound federation transactions on the main process. Set to `false` if using a [federation sender worker](../../workers.md#synapseappfederation_sender).

Defaults to `true`.

Example configuration:
```yaml
send_federation: false
```
---
### `federation_sender_instances`

*(array)* It is possible to scale the processes that handle sending outbound federation requests by running a [`generic_worker`](../../workers.md#synapseappgeneric_worker) and adding it's [`worker_name`](#worker_name) to a `federation_sender_instances` map. Doing so will remove handling of this function from the main process. Multiple workers can be added to this map, in which case the work is balanced across them.

The way that the load balancing works is any outbound federation request will be assigned to a federation sender worker based on the hash of the destination server name. This means that all requests being sent to the same destination will be processed by the same worker instance. Multiple `federation_sender_instances` are useful if there is a federation with multiple servers.

This configuration setting must be shared between all workers handling federation sending, and if changed all federation sender workers must be stopped at the same time and then started, to ensure that all instances are running with the same config (otherwise events may be dropped).

Defaults to `[]`.

Example configurations:
```yaml
federation_sender_instances:
- federation_sender1
```

```yaml
federation_sender_instances:
- federation_sender1
- federation_sender2
```
---
### `instance_map`

*(object)* When using workers this should be a map from [`worker_name`](#worker_name) to the HTTP replication listener of the worker, if configured, and to the main process. Each worker declared under [`stream_writers`](../../workers.md#stream-writers) and [`outbound_federation_restricted_to`](#outbound_federation_restricted_to) needs a HTTP replication listener, and that listener should be included in the `instance_map`. The main process also needs an entry on the `instance_map`, and it should be listed under `main` **if even one other worker exists**. Ensure the port matches with what is declared inside the `listener` block for a `replication` listener. Defaults to `{}`.

Example configurations:
```yaml
instance_map:
  main:
    host: localhost
    port: 8030
  worker1:
    host: localhost
    port: 8034
  other:
    host: localhost
    port: 8035
    tls: true
```

```yaml
instance_map:
  main:
    path: /run/synapse/main_replication.sock
  worker1:
    path: /run/synapse/worker1_replication.sock
```
---
### `stream_writers`

*(object)* Experimental: When using workers you can define which workers should handle writing to streams such as event persistence and typing notifications. Any worker specified here must also be in the [`instance_map`](#instance_map).

See the list of available streams in the [worker documentation](../../workers.md#stream-writers).

Defaults to `{}`.

This setting has the following sub-options:

* `events` (string): Name of a worker assigned to the `events` stream.

* `typing` (string): Name of a worker assigned to the `typing` stream.

* `to_device` (string): Name of a worker assigned to the `to_device` stream.

* `account_data` (string): Name of a worker assigned to the `account_data` stream.

* `receipts` (string): Name of a worker assigned to the `receipts` stream.

* `presence` (string): Name of a worker assigned to the `presence` stream.

* `push_rules` (string): Name of a worker assigned to the `push_rules` stream.

* `device_lists` (string): Name of a worker assigned to the `device_lists` stream.

Example configuration:
```yaml
stream_writers:
  events: worker1
  typing: worker1
```
---
### `outbound_federation_restricted_to`

*(array)* You can restrict outbound federation traffic to only go through a specific subset of workers including the [Secure Border Gateway (SBG)](https://element.io/en/server-suite/secure-border-gateways). Any worker specified here (including the SBG) must also be in the [`instance_map`](#instance_map). [`worker_replication_secret`](#worker_replication_secret) must also be configured to authorize inter-worker communication.

Also see the [worker documentation](../../workers.md#restrict-outbound-federation-traffic-to-a-specific-set-of-workers) for more info.

_Added in Synapse 1.89.0._

Defaults to `[]`.

Example configuration:
```yaml
outbound_federation_restricted_to:
- federation_sender1
- federation_sender2
```
---
### `run_background_tasks_on`

*(string|null)* The [worker](../../workers.md#background-tasks) that is used to run background tasks (e.g. cleaning up expired data). If not provided this defaults to the main process. Defaults to `null`.

Example configuration:
```yaml
run_background_tasks_on: worker1
```
---
### `update_user_directory_from_worker`

*(string|null)* The [worker](../../workers.md#updating-the-user-directory) that is used to update the user directory. If not provided this defaults to the main process.

_Added in Synapse 1.59.0._

Defaults to `null`.

Example configuration:
```yaml
update_user_directory_from_worker: worker1
```
---
### `notify_appservices_from_worker`

*(string|null)* The [worker](../../workers.md#notifying-application-services) that is used to send output traffic to Application Services. If not provided this defaults to the main process.

_Added in Synapse 1.59.0._

Defaults to `null`.

Example configuration:
```yaml
notify_appservices_from_worker: worker1
```
---
### `media_instance_running_background_jobs`

*(string|null)* The [worker](../../workers.md#synapseappmedia_repository) that is used to run background tasks for media repository. If running multiple media repositories you must configure a single instance to run the background tasks. If not provided this defaults to the main process or your single `media_repository` worker.

_Added in Synapse 1.16.0._

Defaults to `null`.

Example configuration:
```yaml
media_instance_running_background_jobs: worker1
```
---
### `redis`

*(object)* Configuration for Redis when using workers. This *must* be enabled when using workers.

_Added in Synapse 1.78.0._

_Changed in Synapse 1.84.0: Added use\_tls, certificate\_file, private\_key\_file, ca\_file and ca\_path attributes_

_Changed in Synapse 1.85.0: Added path option to use a local Unix socket_

_Changed in Synapse 1.116.0: Added password\_path_

This setting has the following sub-options:

* `enabled` (boolean): Whether to use Redis support. Defaults to `false`.

* `host` (string): Optional host to use to connect to Redis. Defaults to `"localhost"`.

* `port` (integer): Optional port to use to connect to Redis. Defaults to `6379`.

* `path` (string): The full path to a local Unix socket file. **If this is used, `host` and `port` are ignored.** Defaults to `"/tmp/redis.sock"`.

* `password` (string|null): Optional password if configured on the Redis instance. Defaults to `null`.

* `password_path` (string|null): Alternative to `password`, reading the password from an external file. The file should be a plain text file, containing only the password. Synapse reads the password from the given file once at startup. Defaults to `null`.

* `dbid` (string|null): Optional redis dbid if needs to connect to specific redis logical db. Defaults to `null`.

* `use_tls` (boolean): Whether to use a TLS connection. Defaults to `false`.

* `certificate_file` (string|null): Optional path to the certificate file. Defaults to `null`.

* `private_key_file` (string|null): Optional path to the private key file. Defaults to `null`.

* `ca_file` (string|null): Optional path to the CA certificate file. Use this one or `ca_path` Defaults to `null`.

* `ca_path` (string|null): Optional path to the folder containing the CA certificate file. Use this one or `ca_file` Defaults to `null`.

Example configuration:
```yaml
redis:
  enabled: true
  host: localhost
  port: 6379
  password_path: <path_to_the_password_file>
  dbid: <dbid>
```
---
## Individual worker configuration

These options configure an individual worker, in its worker configuration file. They should be not be provided when configuring the main process.

Note also the configuration above for [coordinating a cluster of workers](#coordinating-workers).

For guidance on setting up workers, see the [worker documentation](../../workers.md).

---
### `worker_app`

*(string)* The type of worker. The currently available worker applications are listed in [worker documentation](../../workers.md#available-worker-applications).

The most common worker is the [`synapse.app.generic_worker`](../../workers.md#synapseappgeneric_worker).

There is no default for this option.

Example configuration:
```yaml
worker_app: synapse.app.generic_worker
```
---
### `worker_name`

*(string)* A unique name for the worker. The worker needs a name to be addressed in further parameters and identification in log files. We strongly recommend giving each worker a unique `worker_name`. There is no default for this option.

Example configuration:
```yaml
worker_name: generic_worker1
```
---
### `worker_listeners`

*(array)* A worker can handle HTTP requests. To do so, a `worker_listeners` option must be declared, in the same way as the [`listeners` option](#listeners) in the shared config.

Workers declared in [`stream_writers`](#stream_writers) and [`instance_map`](#instance_map) will need to include a `replication` listener here, in order to accept internal HTTP requests from other workers.

Example #2 is using UNIX sockets with a `replication` listener.

Defaults to `[]`.

Example configurations:
```yaml
worker_listeners:
- type: http
  port: 8083
  resources:
  - names:
    - client
    - federation
```

```yaml
worker_listeners:
- type: http
  path: /run/synapse/worker_replication.sock
  resources:
  - names:
    - replication
- type: http
  path: /run/synapse/worker_public.sock
  resources:
  - names:
    - client
    - federation
```
---
### `worker_manhole`

*(integer|null)* A worker may have a listener for [`manhole`](../../manhole.md). It allows server administrators to access a Python shell on the worker.

The example below is a short form for
```yaml
worker_listeners:
  - port: 9000
    bind_addresses: ['127.0.0.1']
    type: manhole
```

It needs also an additional [`manhole_settings`](#manhole_settings) configuration.

Defaults to `null`.

Example configuration:
```yaml
worker_manhole: 9000
```
---
### `worker_daemonize`

*(boolean)* Specifies whether the worker should be started as a daemon process. If Synapse is being managed by [systemd](../../systemd-with-workers/), this option must be omitted or set to `false`. Defaults to `false`.

Example configuration:
```yaml
worker_daemonize: true
```
---
### `worker_pid_file`

*(string|null)* When running a worker as a daemon, we need a place to store the [PID](https://en.wikipedia.org/wiki/Process_identifier) of the worker. This option defines the location of that "pid file".

This option is required if `worker_daemonize` is `true` and ignored otherwise.

See also the [`pid_file` option](#pid_file) option for the main Synapse process.

Defaults to `null`.

Example configuration:
```yaml
worker_pid_file: DATADIR/generic_worker1.pid
```
---
### `worker_log_config`

*(string|null)* This option specifies a yaml python logging config file as described [here](https://docs.python.org/3/library/logging.config.html#configuration-dictionary-schema). See also the [`log_config` option](#log_config) option for the main Synapse process. Defaults to `null`.

Example configuration:
```yaml
worker_log_config: /etc/matrix-synapse/generic-worker-log.yaml
```
---
## Background Updates

Configuration settings related to background updates.

---
### `background_updates`

*(object)* Background updates are database updates that are run in the background in batches. The duration, minimum batch size, default batch size, whether to sleep between batches and if so, how long to sleep can all be configured. This is helpful to speed up or slow down the updates.

This setting has the following sub-options:

* `background_update_duration_ms` (integer): How long in milliseconds to run a batch of background updates for. Defaults to `100`.

* `sleep_enabled` (boolean): Whether to sleep between updates. Defaults to `true`.

* `sleep_duration_ms` (integer): If sleeping between updates, how long in milliseconds to sleep for. Defaults to `1000`.

* `min_batch_size` (integer): Minimum size a batch of background updates can be. Must be greater than 0. Defaults to `1`.

* `default_batch_size` (integer): The batch size to use for the first iteration of a new background update. Defaults to `100`.

Example configuration:
```yaml
background_updates:
  background_update_duration_ms: 500
  sleep_enabled: false
  sleep_duration_ms: 300
  min_batch_size: 10
  default_batch_size: 50
```
---
## Auto Accept Invites

Configuration settings related to automatically accepting invites.

---
### `auto_accept_invites`

*(object)* Automatically accepting invites controls whether users are presented with an invite request or if they are instead automatically joined to a room when receiving an invite. Set the `enabled` sub-option to true to enable auto-accepting invites.

NOTE: Care should be taken not to enable this setting if the `synapse_auto_accept_invite` module is enabled and installed. The two modules will compete to perform the same task and may result in undesired behaviour. For example, multiple join events could be generated from a single invite.

This setting has the following sub-options:

* `enabled` (boolean): Whether to run the auto-accept invites logic. Defaults to `false`.

* `only_for_direct_messages` (boolean): Whether invites should be automatically accepted for all room types, or only for direct messages. Defaults to `false`.

* `only_from_local_users` (boolean): Whether to only automatically accept invites from users on this homeserver. Defaults to `false`.

* `worker_to_run_on` (string|null): Which worker to run this module on. This must match the "worker_name". If not set or `null`, invites will be accepted on the main process. Defaults to `null`.

Example configuration:
```yaml
auto_accept_invites:
  enabled: true
  only_for_direct_messages: true
  only_from_local_users: true
  worker_to_run_on: worker_1
```