Merge pull request #244 from grimneko/master

added new section to the Dovecot expunge page explaining a way to automatize with Ofelia

docs/u_e-dovecot-expunge.md

@@ -31,7 +31,9 @@ docker-compose exec dovecot-mailcow doveadm expunge -u 'mailbox@example.com' mai
 !!! info
     For possible [time spans](https://wiki.dovecot.org/Tools/Doveadm/SearchQuery#section_date_specification) or [search keys](https://wiki.dovecot.org/Tools/Doveadm/SearchQuery#section_search_keys) have a look at [man doveadm-search-query](https://wiki.dovecot.org/Tools/Doveadm/SearchQuery)
 
-## Make it automatic
+## Job scheduler
+
+### via the host system cron
 
 If you want to automate such a task you can create a cron job on your host that calls a script like the one below:
 
@@ -51,3 +53,41 @@ To create a cron job you may execute `crontab -e` and insert something like the
 # Execute everyday at 04:00 A.M.
 0 4 * * * /path/to/your/expunge_mailboxes.sh
 ```
+
+### via Docker job scheduler
+
+To archive this with a docker job scheduler use this docker-compose.override.yml with your mailcow: 
+
+```
+version: '2.1'
+
+ services:
+  
+  ofelia:
+    image: mcuadros/ofelia:latest
+    restart: always
+    command: daemon --docker
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro   
+    network_mode: none
+
+  dovecot-mailcow:
+    labels:
+      - "ofelia.enabled=true"
+      - "ofelia.job-exec.dovecot-expunge-trash.schedule=0 4 * * *"
+      - "ofelia.job-exec.dovecot-expunge-trash.command=doveadm expunge -A mailbox 'Junk' savedbefore 2w"
+      - "ofelia.job-exec.dovecot-expunge-trash.tty=false"
+
+```
+
+The job controller just need access to the docker control socket to be able to emulate the behavior of "exec". Then we add a few label to our dovecot-container to activate the job scheduler and tell him in a cron compatible scheduling format when to run. If you struggle with that schedule string you can use [crontab guru](https://crontab.guru/). 
+This docker-compose.override.yml deletes all mails older then 2 weeks from the "Junk" folder every day at 4 am. To see if things ran proper, you can not only see in your mailbox but also check Ofelia's docker log if it looks something like this:
+
+```
+common.go:124 ▶ NOTICE [Job "dovecot-expunge-trash" (8759567efa66)] Started - doveadm expunge -A mailbox 'Junk' savedbefore 2w,
+common.go:124 ▶ NOTICE [Job "dovecot-expunge-trash" (8759567efa66)] Finished in "285.032291ms", failed: false, skipped: false, error: none,
+```
+
+If it failed it will say so and give you the output of the doveadm in the log to make it easy on you to debug.
+
+In case you want to add more jobs, ensure you change the "dovecot-expunge-trash" part after "ofelia.job-exec." to something else, it defines the name of the job. Syntax of the labels you find at [mcuadros/ofelia](https://github.com/mcuadros/ofelia).