library/roles/docker: add a user to run the docker containers not as root.

docker/defaults/main.yml

@@ -5,9 +5,11 @@ docker_repo_key: '58118E89F3A912897C070ADBF76221572C52609D'
 docker_repo_keyserver: 'hkp://ha.pool.sks-keyservers.net:80'
 # Set to the Debian distribution name if not Ubuntu
 docker_distribution: '{{ ansible_distribution_release | lower }}'
-docker_repo: 'deb https://apt.dockerproject.org/repo {{ ansible_distribution }}-{{ docker_distribution }} main'
+docker_repo: 'deb https://apt.dockerproject.org/repo {{ ansible_distribution | lower }}-{{ docker_distribution }} main'
 
 docker_pkg_status: latest
 docker_packages:
   - docker-engine
 
+docker_run_as_docker_user: True
+docker_user_home: /home/docker

docker/tasks/pkgs.yml

@@ -1,11 +1,15 @@
 ---
 - block:
     - name: Add the Docker repository key
-      apt_key: keyserver={{ docker_repo_keyserver }} id=docker_repo_key state=present
+      apt_key: keyserver={{ docker_repo_keyserver }} id={{ docker_repo_key }} state=present
 
     - name: Add the Docker repository
       apt_repository: repo='{{ docker_repo }}' update_cache=yes
 
+    - name: Create the docker user
+      user: name=docker comment="Docker User" shell=/bin/bash home={{ docker_user_home }} system=yes
+      when: docker_run_as_docker_user
+
     - name: Install Docker
       apt: pkg={{ item }} state={{ docker_pkg_status }} update_cache=yes cache_valid_time=3600
       with_items: '{{ docker_packages }}'
@@ -24,8 +28,11 @@
       apt: pkg={{ item }} state=absent
       with_items: '{{ docker_packages }}'
 
+    - name: Remove the docker user
+      user: name=docker state=absent
+
     - name: Remove the Docker repository key
-      apt_key: keyserver={{ docker_repo_keyserver }} id=docker_repo_key state=absent
+      apt_key: keyserver={{ docker_repo_keyserver }} id={{ docker_repo_key }} state=absent
 
     - name: Remove the Docker repository
       apt_repository: repo='{{ docker_repo }}' state=absent update_cache=yes