Fixed some swarm-related bugs

roles/docker/files/daemon.json

@@ -0,0 +1,4 @@
+{
+    "metrics-addr" : "0.0.0.0:9323",
+    "experimental" : true
+}

roles/docker/handlers/main.yml

@@ -0,0 +1,5 @@
+---
+- name: restart docker
+  service:
+    name: docker
+    state: restarted

roles/docker/tasks/main.yml

@@ -58,3 +58,12 @@
     name: debian
     groups: docker
     append: true
+
+- name: Enable metric endpoint for Prometheus
+  copy:
+    src: daemon.json
+    dest: /etc/docker/daemon.json
+    owner: root
+    group: root
+    mode: '644'
+  notify: restart docker