---
- name: Verify and configure Docker storage driver
  hosts: docker
  tags:
    - docker
    - docker-devicemapper
  tasks:
    - name: Check for existing Docker configuration using devicemapper
      block:
      - name: Query Docker daemon for storage driver
        docker_host_info:
        failed_when: false
        register: docker

      - block:
        - name: Check for a Docker configuration file
          become: True
          stat:
            path: /etc/docker/daemon.json
          register: docker_config_file

        - name: Check whether devicemapper is used in configuration file
          lineinfile:
            path: /etc/docker/daemon.json
            regexp: 'storage-driver.*devicemapper'
            state: absent
          become: True
          changed_when: False
          # `check_mode: True` ensures that we don't modify daemon.json
          check_mode: True
          register: devicemapper_docker
          when: docker_config_file.stat.exists
        when: not (docker.can_talk_to_docker | default(true))

      - name: Fail if devicemapper is in use while another storage driver was requested
        fail:
          msg: "Docker storage driver {{ docker_storage_driver }} was requested, but devicemapper is in use"
        when: (docker.can_talk_to_docker | default(true) and docker.host_info.Driver == 'devicemapper') or (devicemapper_docker.found | default(0) == 1)
      when: docker_storage_driver != 'devicemapper'

    - name: Ensure Docker devicemapper storage is configured
      include_role:
        name: docker-devicemapper
      when: docker_storage_driver == 'devicemapper'