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cloudinit.md

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Cloud Init

In devmachimes/runtime, Cloud-init is used to pass setup parameters when starting a VM. The process of creating cloud-init is handled by the SetupCloudInit function, as described in the Setup Diagram.

In the current version, SetupCloudInit generates a /disks/cloudinit.iso file using the genisoimage command. As specified in the cloud-init documentation, this ISO contains the following files: meta-data, user-data, and network-config.

During the SetupCloudInit process, these files are first stored in the OS temporary directory (/tmp by default). Then, genisoimage is executed. Here’s an example of the command:

genisoimage \
    -o /disks/cloudinit.iso \
    -volid cidata \
    -joliet -rock \
    /tmp/meta-data \
    /tmp/user-data \
    /tmp/network-config

Meta Data

The purpose of this file is to instruct cloud-init to initialize the VM.

Example content of the meta-data file:

instance-id: b1b5cfbbff6a707cd9d83d4386b8f107921b8ff0
local-hostname: my-vm

The runtime changes the instance-id every time the container starts. This is a workaround to ensure configuration changes in devmachines/runtime are applied inside the VM.

User Data

This file provides information about the default user to be created in the VM, including parameters such as username, password, SSH keys, VM hostname, and others.

Example content of the user-data file:

#cloud-config
hostname: my-vm
manage_etc_hosts: true
fqdn: my-vm
user: user
password: pass
ssh_authorized_keys:
    - ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAICeyDWnYtatyEiHKjT/jpLUA7FLMoe97ItrkaLA2cYsX qemu_machine
chpasswd:
    expire: false
users:
    - default

Currently, an unencrypted password (pass) is provided in the config, so we highly recommend not using this in production. Future updates plan to offer an option to set up the VM without a password.

Network Data

This file provides network configuration parameters to the VM. devmachines/runtime retrieves network information from the container's network interface. For more details, see the SetupNetwork section.

Example content of the network-config file:

version: 2
ethernets:
    ens3:
        dhcp4: false
        addresses:
            - 172.18.0.2/16
        gateway4: 172.18.0.1
        nameservers:
            addresses:
                - 8.8.8.8
                - 1.1.1.1

By default, 8.8.8.8 and 1.1.1.1 are set as DNS servers, and ens3 is configured as the network interface inside the VM.

Exploring the Content

You can inspect the contents of cloudinit.iso using the following commands.

To mount the disk to /mnt/iso:

sudo mkdir /mnt/iso
sudo mount -o loop disks/seed.iso /mnt/iso

To unmount cloudinit.iso:

sudo umount /mnt/iso

cdrkit

Currently, the cloudinit.iso file is generated using genisoimage from the cdrkit package. However, in future releases, this method will be deprecated and replaced with QEMU-native image generation.

The following arguments can be used to attach a qcow2 image as a CD drive:

-drive file=/dev/pve/vm-107-cloudinit,if=none,id=drive-ide2,media=cdrom,aio=io_uring \
-device ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2