Add my docker and docker_compose role

Do this in preparation for the keycloak deployment.

playbooks/roles/docker_compose/README.md

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+# Role `docker_compose`
+
+A role for deploying a Docker-Compose-based application.
+It deploys the given Compose file as well as configuration files to the specified hosts and makes sure all services are up-to-date and running.
+The Compose file gets deployed to `/ansible_docker_compose/compose.yaml` and the configuration files get deployed into the `/ansible_docker_compose/configs/` directory.
+A use case for the deployment of the additional configuration files is Composes top-level element `configs` in conjunction with the `configs` option for services.
+
+## Supported Distributions
+
+The following distributions are supported:
+
+- Debian 11
+
+## Required Arguments
+
+For the required arguments look at the [`argument_specs.yaml`](./meta/argument_specs.yaml).
+
+## `hosts`
+
+The `hosts` for this role need to be the machines, for which you want to make sure the given Compose file is deployed and all services of it are up-to-date and running.
+
+## Links & Resources
+
+- <https://docs.docker.com/compose/>
+- <https://docs.docker.com/compose/compose-v2/>
+- <https://docs.docker.com/compose/production/>
+- <https://docs.docker.com/compose/startup-order/>
+- <https://docs.docker.com/compose/compose-file/>
+- <https://docs.docker.com/compose/compose-file/03-compose-file/>
+- <https://docs.docker.com/compose/compose-file/08-configs/>
+- <https://docs.docker.com/compose/compose-file/05-services/#configs>
+- <https://docs.docker.com/engine/reference/commandline/compose_up/>
+- <https://docs.docker.com/engine/reference/commandline/compose_ps/>
+- <https://docs.docker.com/engine/reference/commandline/compose_down/>

playbooks/roles/docker_compose/defaults/main.yaml

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+docker_compose__configuration_files: [ ]

playbooks/roles/docker_compose/handlers/main.yaml

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+- name: docker compose down
+  ansible.builtin.command:
+    cmd: /usr/bin/docker compose down
+    chdir: /ansible_docker_compose
+  become: true
+  changed_when: true  # This is always changed.

playbooks/roles/docker_compose/meta/argument_specs.yaml

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+argument_specs:
+  main:
+    options:
+      docker_compose__compose_file_content:
+        description: >-
+          The content of the Compose file at
+          `/ansible_docker_compose/compose.yaml`.
+        type: str
+        required: true
+      docker_compose__configuration_files:
+        description: >-
+          A list of configuration files to be deployed in the
+          `/ansible_docker_compose/configs/` directory.
+        type: list
+        elements: dict
+        required: false
+        default: [ ]
+        options:
+          name:
+            description: The name of the configuration file.
+            type: str
+            required: true
+          content:
+            description: The content of the configuration file.
+            type: str
+            required: true

playbooks/roles/docker_compose/meta/main.yaml

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+---
+dependencies:
+  - role: distribution_check
+    vars:
+      distribution_check__distribution_support_spec:
+        - name: Debian
+          versions:
+            - 11
+  - role: docker

playbooks/roles/docker_compose/tasks/main.yaml

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+- name: make sure the `/ansible_docker_compose` directory exists
+  ansible.builtin.file:
+    path: /ansible_docker_compose
+    state: directory
+    mode: "0755"
+    owner: root
+    group: root
+  become: true
+
+- name: deploy the Compose file
+  ansible.builtin.copy:
+    content: "{{ docker_compose__compose_file_content }}"
+    dest: /ansible_docker_compose/compose.yaml
+    mode: "0644"
+    owner: root
+    group: root
+  become: true
+  notify: docker compose down
+
+- name: make sure the `/ansible_docker_compose/configs` directory exists
+  ansible.builtin.file:
+    path: /ansible_docker_compose/configs
+    state: directory
+    mode: "0755"
+    owner: root
+    group: root
+  become: true
+
+- name: set `docker_compose__config_files_to_exist` fact initially to an empty list
+  ansible.builtin.set_fact:
+    docker_compose__config_files_to_exist: [ ]
+
+- name: add names from `docker_compose__configuration_files` to `docker_compose__config_files_to_exist` fact
+  ansible.builtin.set_fact:
+    docker_compose__config_files_to_exist: "{{ docker_compose__config_files_to_exist + [ item.name ] }}"  # noqa: jinja[spacing]
+  loop: "{{ docker_compose__configuration_files }}"
+
+- name: find configuration files to remove
+  ansible.builtin.find:
+    paths: /ansible_docker_compose/configs/
+    recurse: false
+    excludes: "{{ docker_compose__config_files_to_exist }}"
+  register: docker_compose__config_files_to_remove
+
+- name: remove all configuration files, which should be removed
+  ansible.builtin.file:
+    path: "{{ item.path }}"
+    state: absent
+  become: true
+  loop: "{{ docker_compose__config_files_to_remove.files }}"
+  notify: docker compose down
+
+- name: make sure all given configuration files are deployed
+  ansible.builtin.copy:
+    content: "{{ item.content }}"
+    dest: "/ansible_docker_compose/configs/{{ item.name }}"
+    mode: "0644"
+    owner: root
+    group: root
+  become: true
+  loop: "{{ docker_compose__configuration_files }}"
+  notify: docker compose down
+
+- name: Flush handlers to make "docker compose down" handler run now
+  ansible.builtin.meta: flush_handlers
+
+- name: docker compose ps --format json before docker compose up
+  ansible.builtin.command:
+    cmd: /usr/bin/docker compose ps --format json
+    chdir: /ansible_docker_compose
+  become: true
+  changed_when: false
+  register: docker_compose__ps_json_before_up
+
+- name: docker compose up --detach --pull always
+  ansible.builtin.command:
+    cmd: /usr/bin/docker compose up --detach --pull always
+    chdir: /ansible_docker_compose
+  become: true
+  changed_when: false
+  # The changed for this task is tried to be determined by the "potentially
+  # report changed" task together with the "docker compose ps --format json
+  # [...]" tasks.
+
+- name: docker compose ps --format json after docker compose up
+  ansible.builtin.command:
+    cmd: /usr/bin/docker compose ps --format json
+    chdir: /ansible_docker_compose
+  become: true
+  changed_when: false
+  register: docker_compose__ps_json_after_up
+
+- name: potentially report changed
+  ansible.builtin.debug:
+    msg: "If this reports changed, then the docker compose containers changed."
+  changed_when: (docker_compose__ps_json_before_up.stdout | from_json | community.general.json_query('[].ID') | sort)
+                != (docker_compose__ps_json_after_up.stdout | from_json | community.general.json_query('[].ID') | sort)