ACME Certificate Watcher

A lightweight and failsafe tool for maintaining a valid TLS certificate-key file pair.

acme-cert-watcher is planned to be used in production at Ameliorated LLC to maintain TLS capabilities for our webservices. acme-cert-watcher relies primarily on instant-acme and reqwest for its functionality.

Usage

acme-cert-watcher.exe [OPTIONS] --provider <PROVIDER> --email <EMAIL> --key-path <KEY_PATH> --cert-path <CERT_PATH> --serve-dir <SERVE_DIR>

Options:
  -p, --provider <PROVIDER>
          ACME provider of choice [possible values: zerossl, buypass, letsencrypt]
  -f, --fallback <FALLBACK>
          Optional fallback provider(s) incase the provider specified by --provider repeatedly fails and the cert is within 7 days of expiration [possible values: zerossl, buypass, letsencrypt]
  -d, --domain <DOMAIN>
          Domain(s) for ACME certificates
  -e, --email <EMAIL>
          Contact email for ACME
  -k, --key-path <KEY_PATH>
          Path to destination private key file
  -c, --cert-path <CERT_PATH>
          Path to destination certificate file
  -s, --serve-dir <SERVE_DIR>
          Path to public web serve directory. Must be actively hosted by a webserver for HTTP-01 validation
      --api-key <API_KEY>
          API key for ZeroSSL. Alternative to specifying EAB credentials
      --eab-kid <EAB_KID>
          EAB KID for ZeroSSL. Must be paired with --eab-hmac-key
      --eab-hmac-key <EAB_HMAC_KEY>
          EAB HMAC key for ZeroSSL. Must be paired with --eab-kid
      --cache-dir <CACHE_DIR>
          Cache directory for ACME account credentials, and ZeroSSL EAB credentials (if applicable) [default: ./acme_cache]
  -r, --reload-command <RELOAD_COMMAND>
          Optional command to be run after a successful cert update
  -h, --help
          Print help
  -V, --version
          Print version

Examples

./acme-cert-watcher -p zerossl --api-key ZEROSSL-API-KEY -f buypass -e example@fastmail.com -d example.styris.net -k server.key -c server.crt -s ./dist

To run a command after renewal, such as reloading nginx:

sudo ./acme-cert-watcher -p zerossl --api-key ZEROSSL-API-KEY -f buypass -e example@fastmail.com -d example.styris.net -k server.key -c server.crt -s ./dist -r "systemctl reload nginx"

Behavior

acme-cert-watcher expects files in the directory specified by --serve-dir (-s) to be publicly available at --domain for HTTP-01 certificate validation, and will not be able to renew certificates otherwise.

Renewals happen once the certificate has 30 days or less left before expiration.

In the event that a failure occurs, acme-cert-watcher will retry with an exponentially increasing delay (up to an hour) until it is able to successfully renew the certificate. If a fallback(s) is provided, it will only be used under the following conditions:

• The existing certificate (if present) only has 7 days or less before expiration
• The retry delay for the main provider has reached an hour with no success