Exclude mastodon cache from backups

tasks/main.yml

@@ -31,6 +31,13 @@
     - "{{ mastodon_docker_backup_storage }}"
     # cache storage intentionally omitted
 
+- name: Make sure cache directory is excluded from backup
+  lineinfile:
+    path: "/backup-dirs-exclude"
+    line: "{{ item }}"
+  loop:
+    - "{{ mastodon_docker_cache_storage }}"
+
 - name: Copy the docker compose file to server
   template:
     src: "docker-compose.yml.j2"