---
# Upgrading docker engine may cause containers to stop. Take a snapshot of the
# running containers prior to a potential upgrade of Docker.

- name: Check which containers are running
  command: docker ps -f 'status=running' -q
  become: true
  # If Docker is not installed this command may exit non-zero.
  failed_when: false
  changed_when: false
  register: running_containers

# APT starts Docker engine right after installation, which creates
# iptables rules before we disable iptables in Docker config
- block:
    - name: Check if docker systemd unit exists
      stat:
        path: /etc/systemd/system/docker.service
      register: docker_unit_file

    - name: Mask the docker systemd unit on Debian/Ubuntu
      file:
        src: /dev/null
        dest: /etc/systemd/system/docker.service
        owner: root
        group: root
        state: link
      become: true
      when: not docker_unit_file.stat.exists
  when: ansible_facts.os_family == 'Debian'

- name: Install packages
  package:
    name: "{{ docker_packages | select | list }}"
    cache_valid_time: "{{ apt_cache_valid_time if ansible_facts.os_family == 'Debian' else omit }}"
    update_cache: true
    state: present
  become: true
  register: docker_install_result

# If any packages were updated, and any containers were running, wait for the
# daemon to come up and start all previously running containers.

- block:
    # At some point (at least on CentOS 7) Docker CE stopped starting
    # automatically after an upgrade from legacy docker . Start it manually.
    - name: Start docker
      systemd:
        name: docker
        state: started
        enabled: true
        masked: false
      become: true

    - name: Wait for Docker to start
      command: docker info
      become: true
      changed_when: false
      register: result
      until: result is success
      retries: 6
      delay: 10

    - name: Ensure containers are running after Docker upgrade
      # noqa no-changed-when
      command: "docker start {{ running_containers.stdout }}"
      become: true
      changed_when: true
  when:
    - docker_install_result is changed
    - running_containers.rc == 0
    - running_containers.stdout != ''