install-docker: option to install docker-compose

The install-docker role currently takes care of setting up Docker
however it lacks the ability to install docker-compose at the moment
which is quite useful.

This adds a variable which defaults to false that allows you to use the
role to install docker-compose.  It was decided to be put within the
install-docker role because that role already manages the repository
configuration and therefore provide consistency with the repository that
is used to install docker-compose.

Change-Id: Ia6f4ed88b4baf53bd671c7a7b48a1564ff2c866d

roles/install-docker/README.rst

@@ -18,6 +18,12 @@ An ansible role to install docker and configure it to use mirrors if available.
    By default this role adds repositories to install docker from upstream
    docker. Set this to False to use the docker that comes with the distro.
 
+.. zuul:rolevar:: docker_compose_install
+   :default: False
+
+   This role does not install docker-compose by default but you can use
+   this setting to install docker-compose as well.
+
 .. zuul:rolevar:: docker_update_channel
    :default: stable
 

roles/install-docker/defaults/main.yaml

@@ -4,6 +4,7 @@ docker_group: docker
 #                  The default option will return an empty list which
 #                  allows folks to override these lists as they see fit.
 docker_distro_packages: "{{ _docker_distro_packages | default([]) }}"
+docker_compose_install: false
 docker_upstream_distro_packages: "{{ _docker_upstream_distro_packages | default([]) }}"
 docker_upstream_distro_required_packages: "{{ _docker_upstream_distro_required_packages | default([]) }}"
 docker_update_channel: stable

roles/install-docker/tasks/main.yaml

@@ -57,6 +57,13 @@
 
 - include_tasks: "docker-{{ (use_upstream_docker | bool) | ternary('upstream', 'distro') }}.yaml"
 
+- name: Install docker-compose
+  become: true
+  package:
+    name: docker-compose
+    state: present
+  when: docker_compose_install | bool
+
 - name: Flush handlers before role exit
   meta: flush_handlers