Setup log rotation for docker.

roles/docker/files/daemon.json

@@ -0,0 +1,7 @@
+{
+  "log-driver": "json-file",
+  "log-opts": {
+    "max-size": "10m",
+    "max-file": "10"
+  }
+}

roles/docker/tasks/main.yml

@@ -15,10 +15,16 @@
 - name: install docker
   apt: pkg={{ item }} state=latest
   with_items:
-     - docker-engine
-     - python-docker
+    - docker-engine
+    - python-docker
   when: ansible_distribution == 'Ubuntu' and ansible_distribution_release == 'xenial'
 
+- name: Setup log rotation.
+  copy:
+    src: files/daemon.json
+    dest: /etc/docker/daemon.json
+  tags: ['settings']
+
 - name: make sure service is started
   systemd:
     name: docker.service