Check that docker daemon is running before continuing with install/ch…

…anges (#39)

* #38 - Prevent potential unnecessary service restarts by sorting daemon.json by keys to ensure a net-zero changes to the config don\t cause diffs.

* #38 - Check that docker daemon is running any time the service is potentially started/restarted.

roles/docker_node/tasks/docker-daemon-running.yml

@@ -0,0 +1,10 @@
+# before moving on, make sure the docker daemon is actually up, by asking it for a list of images
+- name: ask docker for a list of images
+  docker_image_info: {}
+  become: "{{ true if docker_become_user is defined else false }}"
+  become_user: "{{ docker_become_user }}"
+  # try every 10 seconds for a minute to see if the service comes up
+  delay: 10
+  retries: 6
+  register: docker_image_info_result
+  until: docker_image_info_result is not failed

roles/docker_node/tasks/main.yml

@@ -20,6 +20,9 @@
 # also restart the service if any chnages to the packages were made
 - include_tasks: docker-enable-start-restart.yml
 
+- name: make sure docker is running
+  include_tasks: docker-daemon-running.yml
+
 - name: install /etc/docker/daemon.json
   template:
     src: daemon.json
@@ -32,3 +35,6 @@
   vars:
     docker_service_state: restarted
   when: docker_daemon_json_result.changed
+
+- name: make sure docker is running
+  include_tasks: docker-daemon-running.yml

roles/docker_node/templates/daemon.json

@@ -1 +1 @@
-{{ docker_daemon_config | to_nice_json(indent=2) }}
+{{ docker_daemon_config | to_nice_json(indent=2, sort_keys=True) }}