Restart quadlet when mounted host files changed the state

[SrX]

Looking for advice on how to mount host files with configuration into containers, and get restarted containers if changes occur in the configuration files.

In the example below configuration file for caddy mounted properly, but it not reflect later changes on it, since the role cannot detect "dependant" services of the configuration file and restart it.

Is there any workaround for this case or already available configuration model?

- name: Manage caddy via podman quadlet
  hosts: nms
  become: true
  tags:
    - caddy
  vars:
    podman_create_host_directories: true
    podman_quadlet_specs:
      - name: caddy
        file: /opt/nms/Caddyfile
        file_content: |
          {
            auto_https off
          }

          http://127.0.0.1 {
            respond "ok (loopback)" 200
          }

          https://127.0.0.1 {
            tls internal
            respond "ok (loopback)" 200
          }

      - name: caddy
        type: container
        Unit:
          Description: caddy
        Install:
          WantedBy: default.target
        Container:
          Image: "docker.io/caddy:2.10.2"
          ContainerName: caddy
          Network: nms
          Volume: "/opt/nms/Caddyfile:/etc/caddy/Caddyfile:ro"
          PublishPort:
            - 80:80
            - 443:443

  roles:
    - fedora.linux_system_roles.podman

[richm]

hmm - not sure how to do that - the "Ansible way" would be for the task which writes the file https://github.com/linux-system-roles/podman/blob/main/tasks/create_update_quadlet_spec.yml#L37-L60 to do a notify: something, and have a handler restart. I suppose the simple way to do it would be to assume all of the containers specified in the podman_quadlet_specs depend on the file elements, and just restart all of the services if any of the file elements change.

I think for more fine grained control, and especially to handle cases where you want to restart specific services when a specific event changes e.g. "when I change secret X, restart services A and B, but not C". One way would be to add a "restart_services: list" to the secret spec and the quadlet spec. e.g.

      - name: caddy
        file: /opt/nms/Caddyfile
        restart_services: [caddy]

Then, if the role sees that Caddyfile changed, it would restart the caddy service. I suppose the dependency could go the other way too - have a watch_files: [/opt/nms/Caddyfile] on the caddy container entry.

For now - the workaround is not pretty:

• stat the config file to get the sha hash before
• run the podman role
• stat the config file to get the sha hash after
• restart the service if sha before != sha after

[SrX]

I've solved it via writing the hash of config file to environment vars, since container unit changes the state, it get restarted:

      - name: caddy.config
        file: /opt/nms/Caddyfile
        file_content: "{{ caddy_file }}"
      - name: caddy
        type: container
        Unit:
          Description: caddy
        Install:
          WantedBy: default.target
        Container:  
          ...
          Volume: "/opt/nms/Caddyfile:/etc/caddy/Caddyfile:ro"
          Environment:
            - Caddyfile_sha1="{{ caddy_file | sha1 }}"

In terms of managing dependencies of service to config files, it's not easy, as file has to be rendered before the containers, and service cannot be restarted when files has changes, service may not exists yet or be restarted multiple times for each file that depends on it.

Using handlers and notifies seems right, but handlers cannot be dynamically called with names of services, quadlet definition can have many services.