Rearanged the playbook to use ansible roles:

http://docs.ansible.com/ansible/playbooks_roles.html

also made keystone run

roles/mariadb/tasks/main.yml

@@ -0,0 +1,16 @@
+# Install a docker based mariadb.
+---
+- include: ../common/tasks/docker.yml
+- name: install service file.
+  template:
+    src: files/mysql.service
+    dest: /etc/systemd/system/mysql.service
+    mode: 644
+    owner: root
+    group: root
+- name: install service file
+  command: systemctl daemon-reload
+- name: make sure service is started
+  systemd:
+    name: mysql.service
+    state: started