Disable GitLab Prometheus and set tsdb retention time to 12h

TODO.md

@@ -6,3 +6,4 @@
     - [x] Make it inaccessible to anyone but root (`-rw------`)
 - [x] Add [Drone runner](https://docs.drone.io/runner/docker/installation/linux/)
 - [ ] Figure out how to dependably store `.env` files (Ansible vault? Something else?)
+- [ ] Check out docker swarm and current best practices for Ansible

docker/web/docker-compose.yaml

@@ -79,11 +79,17 @@ services:
         # https://docs.gitlab.com/omnibus/settings/rpi.html
         puma['worker_processes'] = 2
         sidekiq['concurrency'] = 9
-        prometheus_monitoring['enable'] = false
 
         nginx['listen_port'] = 80
         nginx['listen_https'] = false
 
+        # https://forum.gitlab.com/t/clear-up-postges-prometheus-data/38216/3
+        prometheus_monitoring['enable'] = false
+        prometheus['enable'] = false
+        prometheus['flags'] = {
+          'storage.tsdb.retention.time' => "12h"
+        }
+
   jupyter:
     image: ihaskell-docker:1.0
     # ports: