Restart Mailman 3 containers when configs change

Add a handler for restarting Mailman 3 containers if they're up, and
notify it from all of the copy tasks for configuration files. Check
for the uwsgi processes that Django runs under to determine whether
the containers are running.

Change-Id: I73be59be773fdde100999c7872520aab1d9e2066

playbooks/roles/mailman3/handlers/main.yaml

@@ -7,3 +7,6 @@
   service:
     name: apache2
     state: reloaded
+
+- name: mailman restart containers
+  include_tasks: roles/mailman3/handlers/restart_mailman.yaml

playbooks/roles/mailman3/handlers/restart_mailman.yaml

@@ -0,0 +1,15 @@
+- name: mailman check for running containers
+  command: pgrep -f uwsgi
+  ignore_errors: yes
+  register: uwsgi_pids
+
+- name: mailman restart containers if running
+  # Also makes sure the containers weren't just restarted by an image update
+  when: uwsgi_pids.rc == 0 and "is up-to-date" in mailman_dcup.stdout
+  block:
+    - name: down containers
+      shell:
+        cmd: docker-compose -f /etc/mailman-compose/docker-compose.yaml down
+    - name: up containers
+      shell:
+        cmd: docker-compose -f /etc/mailman-compose/docker-compose.yaml up -d

playbooks/roles/mailman3/tasks/main.yaml

@@ -43,6 +43,7 @@
     owner: 100
     group: 65533
     mode: '0644'
+  notify: mailman restart containers
 
 - name: Ensure Mailman database volume directory exists
   file:
@@ -76,6 +77,7 @@
     owner: 100
     group: 101
     mode: '0644'
+  notify: mailman restart containers
 
 - name: Check for initial setup flag file
   stat:
@@ -100,6 +102,7 @@
     owner: 100
     group: 101
     mode: '0644'
+  notify: mailman restart containers
 
 - name: Copy our max_allowed_packet override config
   copy:
@@ -108,6 +111,7 @@
     owner: 999
     group: 999
     mode: '0644'
+  notify: mailman restart containers
 
 - name: Ensure /etc/mailman-compose directory
   file:
@@ -120,6 +124,7 @@
     src: docker-compose.yaml.j2
     dest: /etc/mailman-compose/docker-compose.yaml
     mode: '0600'
+  notify: mailman restart containers
 
 - name: Run docker-compose pull
   shell:
@@ -130,6 +135,7 @@
   shell:
     cmd: docker-compose up -d
     chdir: /etc/mailman-compose/
+  register: mailman_dcup
 
 - name: Run docker prune to cleanup unneeded images
   shell: