Update pm2 tasks to update the config correctly

Previously, if you changed the pm2 ecosystem file content, it wouldn't actually be reflected in the running services. Now it will be!

deploy/playbooks/setup.yml

@@ -65,7 +65,7 @@
 
     - name: Create pm2 ecosystem file
       copy:
-        content: >
+        content: |
           module.exports = {
             apps: [
               {
@@ -78,12 +78,26 @@
               }
             ]
           }
-        dest: "/srv/impress-2020/ecosystem.config.js"
+        dest: "~/ecosystem.config.js"
+        # Create a temporary backup file, so we can use it to delete the old
+        # version of the services. (This is important if e.g. a service is
+        # removed or renamed, in which case deleting from the *new* config file
+        # wouldn't include it.)
+        backup: yes
+      register: pm2_ecosystem_file
 
-    - name: Start pm2 ecosystem (even if the app isn't ready yet)
-      command:
-        chdir: "/srv/impress-2020"
-        cmd: "pm2 start ecosystem.config.js"
+    - name: Delete old pm2 services if config file changed
+      command: "pm2 delete {{ pm2_ecosystem_file.backup_file | quote }}"
+      when: pm2_ecosystem_file is changed and pm2_ecosystem_file.backup_file is defined
+
+    - name: Delete old pm2 config file if it changed
+      file:
+        path: "{{ pm2_ecosystem_file.backup_file }}"
+        state: absent
+      when: pm2_ecosystem_file is changed and pm2_ecosystem_file.backup_file is defined
+
+    - name: Start pm2 services
+      command: "pm2 start ~/ecosystem.config.js"
 
     - name: Save pm2 startup script
       command: pm2 save