Add a script for trimming storage

roles/mastodon/tasks/main.yml

@@ -28,3 +28,5 @@
     src: docker-compose.yml.j2
     dest: /home/mastodon/live/docker-compose.yml
   notify: "docker-compose up"
+
+- import_tasks: maintenance.yml

roles/mastodon/tasks/maintenance.yml

@@ -0,0 +1,5 @@
+---
+- name: Install storage trimmer
+  template:
+    src: trim_storage.sh.j2
+    dest: /usr/local/bin/trim_storage.sh