docker: restart docker and containerd in handlers

This is more efficient when there are no changes.

Change-Id: I50ef8ea28e7d83e2788e1ceaee93c97765031a15

roles/docker/handlers/main.yml

@@ -0,0 +1,21 @@
+---
+- name: Reload docker service file
+  become: True
+  systemd:
+    name: docker
+    daemon_reload: yes
+  notify:
+    - Restart docker
+
+- name: Restart docker
+  systemd:
+    name: docker
+    state: restarted
+    masked: no
+  become: True
+
+- name: Restart containerd
+  service:
+    name: containerd
+    state: restarted
+  become: True

roles/docker/tasks/config.yml

@@ -35,7 +35,8 @@
     content: "{{ docker_config | to_nice_json }}"
     dest: /etc/docker/daemon.json
     mode: 0644
-  register: docker_configured
+  notify:
+    - Restart docker
 
 - name: Remove old docker options file
   become: True
@@ -47,6 +48,8 @@
     - not docker_http_proxy
     - not docker_https_proxy
     - not docker_no_proxy
+  notify:
+    - Reload docker service file
 
 - name: Ensure docker service directory exists
   become: True
@@ -70,32 +73,16 @@
     docker_http_proxy | length > 0 or
     docker_https_proxy | length > 0 or
     docker_no_proxy | length > 0
+  notify:
+    - Reload docker service file
 
-- name: Reload docker service file
-  become: True
-  systemd:
-    name: docker
-    daemon_reload: yes
-  register: docker_reloaded
+- name: Flush handlers
+  meta: flush_handlers
 
-- name: Start docker
+- name: Start and enable docker
   systemd:
     name: docker
     state: started
-    masked: no
-  become: True
-
-- name: Restart docker
-  systemd:
-    name: docker
-    state: restarted
-    masked: no
-  become: True
-  when: docker_configured.changed or docker_reloaded.changed
-
-- name: Enable docker
-  systemd:
-    name: docker
     enabled: yes
     masked: no
   become: True

roles/docker/tasks/configure-containerd-for-zun.yml

@@ -16,7 +16,8 @@
     owner: "{{ config_owner_user }}"
     group: "{{ config_owner_group }}"
   become: True
-  register: cni_configured
+  notify:
+    - Restart containerd
 
 - name: Ensuring CNI bin directory exist
   file:
@@ -40,11 +41,5 @@
     dest: "/etc/containerd/config.toml"
     mode: "0660"
   become: true
-  register: containerd_configured
-
-- name: Restart containerd
-  service:
-    name: containerd
-    state: restarted
-  become: True
-  when: cni_configured.changed or containerd_configured.changed
+  notify:
+    - Restart containerd

roles/docker/tasks/install.yml

@@ -12,23 +12,22 @@
 
 # APT starts Docker engine right after installation, which creates
 # iptables rules before we disable iptables in Docker config
+- block:
+    - name: Check if docker systemd unit exists
+      stat:
+        path: /etc/systemd/system/docker.service
+      register: docker_unit_file
 
-- name: Check if docker systemd unit exists
-  stat:
-    path: /etc/systemd/system/docker.service
-  register: docker_unit_file
-
-- name: Mask the docker systemd unit on Debian/Ubuntu
-  file:
-    src: /dev/null
-    dest: /etc/systemd/system/docker.service
-    owner: root
-    group: root
-    state: link
-  become: true
-  when:
-    - ansible_facts.os_family == 'Debian'
-    - not docker_unit_file.stat.exists
+    - name: Mask the docker systemd unit on Debian/Ubuntu
+      file:
+        src: /dev/null
+        dest: /etc/systemd/system/docker.service
+        owner: root
+        group: root
+        state: link
+      become: true
+      when: not docker_unit_file.stat.exists
+  when: ansible_facts.os_family == 'Debian'
 
 - name: Install packages
   package: