podman-container-systemd

Role sets up container(s) to be run on host with help of systemd. Podman implements container events but does not control or keep track of the life-cycle. That's job of external tool as Kubernetes in clusters, and systemd in local installs.

I wrote this role in order to help managing podman containers life-cycle on my personal server which is not a cluster. Thus I want to use systemd for keeping them enabled and running over reboots.

What role does:

installs Podman
pulls required images
on consecutive runs it pulls image again, and restarts container if image changed (not for pod yet)
creates systemd file for container or pod
creates kubernetes yaml for pod
creates volume directories for containers if they do not exist. (for pod use DirectoryOrCreate)
set's container or pod to be always automatically restarted if container dies.
makes container or pod enter run state at system boot
adds or removes containers exposed ports to firewall.
It takes parameter for running rootless containers under given user

For reference, see these two blogs about the role:

Blogs describe how you can single container, or several containers as one pod using this module.

Note for running rootless containers:

You need to have the user created prior running this role.
The user should have entries in /etc/sub[gu]id files for namespace range. If not, this role adds some variables there in order to get something going, but preferrably you check them.
Some control things like memory or other resource limit's won't work as user.
You want to increase systemd_TimeoutStartSec heavily, as we can not prefetch the images before systemd unit start. So systemd needs to wait for podman to pull images prior it starts container. Might take minutes depending on your network connection, and container image size.

Requirements

Requires system which is capable of running podman, and that podman is found from package repositories. Role installs podman. Role also installs firewalld if user has defined container_firewall_ports -variable. Installs kubeval for a pod if container_pod_yaml_template_validation: true.

Role Variables

Role uses variables that are required to be passed while including it. As there is option to run one container separately or multiple containers in pod, note that some options apply only to other method.

container_image_list - list of container images to run. If more than one image is defined, then the containers will be run in a pod. It is possible to define it as a dictionary to include authentication information per image, like so:

container_image_list:
  - image: docker.io/imagename
    user: exampleuser
    password: examplepw
  - image: docker.io/imagename2

container_image_user - optional default username to use when authenticating to remote registries
container_image_password - optional default password to use when authenticating to remote registries
container_name - Identify the container in systemd and podman commands. Systemd service file be named container_name--container-pod.service. This can be overwritten with service_name.
container_run_args - Anything you pass to podman, except for the name and image while running single container. Not used for pod.
container_cmd_args - Any command and arguments passed to podman-run after specifying the image name. Not used for pod.
container_run_as_user - Which user should systemd run container as. Defaults to root.
container_run_as_group - Which group should systemd run container as. Defaults to root.
container_dir_owner - Which owner should the volume dirs have. Defaults to container_run_as_user. If you use :U as a volume option podman will set the permissions for the user inside the container automatically. Quote: The :U suffix tells Podman to use the correct host UID and GID based on the UID and GID within the container, to change recursively the owner and group of the source volume. Warning use with caution since this will modify the host filesystem.
container_dir_group - Which group should the volume dirs have. Defaults to container_run_as_group.
container_dir_mode - Which permissions should the volume dirs have. Defaults to '0755'.
container_state - container is installed and run if state is running, and stopped and systemd file removed if absent
container_firewall_ports - list of ports you have exposed from container and want to open firewall for. When container_state is absent, firewall ports get closed. If you don't want firewalld installed, don't define this.
systemd_TimeoutStartSec - how long does systemd wait for container to start?
systemd_tempdir - Where to store conmon-pidfile and cidfile for single containers. Defaults to %T on systems supporting this specifier (see man 5 systemd.unit) /tmp otherwise.
service_name - How the systemd service files are named. Defaults to "{{ container_name }}-container-pod-{{ container_run_as_user }}.service".
service_files_dir - Where to store the systemd service files. Defaults to /usr/local/lib/systemd/system for root and "{{ user_info.home }}/.config/systemd/user for a rootless user
service_files_owner - Which user should own the systemd service files. Defaults to root.
service_files_group - Which group should own the systemd service files. Defaults to root.
service_files_mode - Which permissions should the systemd service files have. Defaults to 0644.
container_pod_yaml - Path to the pod yaml file. Required for a pod.
container_pod_yaml_deploy - Wheter to deploy the pod yaml file. Defaults to false
container_pod_yaml_template - Template to use for pod yaml deploy. As the template doesn't include every possible configuration option it is possible to overwrite it with your own template. Defaults to templates/container-pod-yaml.j2.
container_pod_yaml_template_validation - Wheter to validate the deployed pod yaml file. Defaults to false.
container_pod_labels - Defines labels for container_pod_yaml_deploy.
container_pod_volumes - Defines volumes for container_pod_yaml_deploy.
container_pod_containers - Defines containers for container_pod_yaml_deploy.

This playbook doesn't have python module to parse parameters for podman command. Until that you just need to pass all parameters as you would use podman from command line. See man podman or podman tutorials for info.

If you want your images to be automatically updated, add this label to container_cmd_args: --label "io.containers.autoupdate=image"

Never use ansible.builtin.import_role to execute this role if you intend to use it more than once per playbook, or you will fall in this anti-pattern.

Dependencies

containers.podman (collection)
ansible.posix (collection)

Example Playbook

See the tests/main.yml for sample. In short, include role with vars.

Root container:

- name: tests container
  vars:
    container_image_list: 
      - sebp/lighttpd:latest
    container_name: lighttpd
    container_run_args: >-
      --rm
      -v /tmp/podman-container-systemd:/var/www/localhost/htdocs:Z,U
      --label "io.containers.autoupdate=image"
      -p 8080:80
    #container_state: absent
    container_state: running
    container_firewall_ports:
      - 8080/tcp
      - 8443/tcp
  ansible.builtin.include_role:
    name: podman-container-systemd

Rootless container:

- name: ensure user
  user:
    name: rootless_user
    comment: I run sample container

- name: tests container
  vars:
    container_run_as_user: rootless_user
    container_run_as_group: rootless_user
    container_image_list: 
      - sebp/lighttpd:latest
    container_name: lighttpd
    container_run_args: >-
      --rm
      -v /tmp/podman-container-systemd:/var/www/localhost/htdocs:Z,U
      -p 8080:80
    #container_state: absent
    container_state: running
    container_firewall_ports:
      - 8080/tcp
      - 8443/tcp
  ansible.builtin.include_role:
    name: podman-container-systemd

Rootless Pod:

- name: ensure user
  user:
    name: rootless_user
    comment: I run sample container

- name: tests pod
  vars:
    container_run_as_user: rootless_user
    container_run_as_group: rootless_user
    container_image_list:
      - sebp/lighttpd:latest
    container_name: lighttpd-pod
    container_pod_yaml: /home/rootless_user/lighttpd-pod.yml
    container_pod_yaml_deploy: true
    container_pod_yaml_template_validation: true
    container_pod_labels:
      app: "{{ container_name }}"
      io.containers.autoupdate: 'image(1)'
    container_pod_volumes:
      - name: htdocs
        hostPath:
          path: /tmp/podman-container-systemd
          type: DirectoryOrCreate
    container_pod_containers:
      - name: lighttpd
        image: sebp/lighttpd:latest
        volumeMounts:
          - name: htdocs
            mountPath: /var/www/localhost/htdocs:Z
        ports:
          - containerPort: 80
            hostPort: 8080
    container_state: running
    container_firewall_ports:
      - 8080/tcp
      - 8443/tcp
  ansible.builtin.include_role:
    name: podman-container-systemd

License

GPLv3

Author Information

Ilkka Tengvall ilkka.tengvall@iki.fi

grizz/podman-container-systemd