Implement tripleo-docker-rm role

tripleo-docker-rm
=================

An Ansible role to remove Docker containers when Podman is enabled.

Requirements
------------

It requires python-docker on the host.

Role variables
--------------

- container_cli: -- Name of the Container CLI tool (default to docker).
- containers_to_rm: -- List of containers to remove.

Example Playbook
----------------

Sample playbook to call the role:

  - name: Remove Nova API docker containers
    hosts: all
    roles:
      - tripleo-docker-rm
    vars:
      containers_to_rm:
        - nova_api
        - nova_api_cron
      container_cli: podman

This role will be consummed by THT in post_upgrade_tasks.

Change-Id: I03ad922c61ddd0b4a34935e1e17c0b37cd71ee03

releasenotes/notes/tripleo-docker-rm-b64297d5f9f42988.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - |
+    The new tripleo-docker-rm will be useful to remove the containers that
+    were managed by Docker and that are now managed by Podman.

roles/tripleo-docker-rm/README.md

@@ -0,0 +1,40 @@
+tripleo-docker-rm
+=================
+
+An Ansible role to remove Docker containers when Podman is enabled.
+
+Requirements
+------------
+
+It requires python-docker on the host.
+
+Role variables
+--------------
+
+- container_cli: -- Name of the Container CLI tool (default to docker).
+- containers_to_rm: -- List of containers to remove.
+
+Example Playbook
+----------------
+
+Sample playbook to call the role:
+
+  - name: Remove Nova API docker containers
+    hosts: all
+    roles:
+      - tripleo-docker-rm
+    vars:
+      containers_to_rm:
+        - nova_api
+        - nova_api_cron
+      container_cli: podman
+
+License
+-------
+
+Free software: Apache License (2.0)
+
+Author Information
+------------------
+
+OpenStack TripleO team

roles/tripleo-docker-rm/defaults/main.yaml

@@ -0,0 +1,2 @@
+---
+container_cli: docker

roles/tripleo-docker-rm/tasks/main.yaml

@@ -0,0 +1,17 @@
+---
+- name: Check if docker is installed
+  stat:
+    path: /usr/bin/docker
+  register: docker_path_stat
+
+- set_fact:
+    docker_installed: "{{ docker_path_stat.results | map(attribute='stat') | map(attribute='exists') is any }}"
+
+- name: remove "{{ containers_to_rm|join(', ') }}" containers
+  docker_container:
+    name: "{{ item }}"
+    state: absent
+  when:
+    - container_cli == 'podman'
+    - docker_installed
+  with_items: "{{ containers_to_rm }}"