ejabberd: mom_mam throws error

Question

I've just installed ejabberd from the sources (18.04) with MySQL support and changed the configuration file respectively. Basically everything works: ejabberd starts, I can register users, users can connect and send messages. I also see all users in the database so I assume the setup is so far correct.

Now I want to use the mod mod_mam to archive all messages. For this I added to the ejabberd.yaml file the following lines:

modules:
  ...
  mod_mam:
    db_type: sql
    default: always
  ...

However, when I sent an offline message, I get the following error -- actually two similar errors for two functions using both the offline message hook:

[error] <0.541.0>@ejabberd_hooks:safe_apply:383 Hook offline_message_hook crashed when running mod_mam:offline_message/1: 
** Reason = {error,function_clause,[{mod_mam,offline_message,[{file,"src/mod_mam.erl"},{line,366}],[ok]},{ejabberd_hooks,safe_apply,[{file,"src/ejabberd_hooks.erl"},{line,380}],4},{ejabberd_hooks,run_fold1,[{file,"src/ejabberd_hooks.erl"},{line,364}],4},{ejabberd_sm,route,[{file,"src/ejabberd_sm.erl"},{line,143}],1},{ejabberd_local,route,[{file,"src/ejabberd_local.erl"},{line,73}],1},{ejabberd_router,do_route,[{file,"src/ejabberd_router.erl"},{line,368}],1},{ejabberd_router,route,[{file,"src/ejabberd_router.erl"},{line,93}],1},{ejabberd_c2s,check_privacy_then_route,[{file,"src/ejabberd_c2s.erl"},{line,823}],2}]}

With an older installation (17.01) everything worked fine. But I don't know if additional MySQL tables are required. When I look into my current database, I actually all messages (including offline message) get stored in table archive.

Do you use only the modules included in ejabberd, or did you install any of the contributed, or other custom modules? — Badlop
Your question steered me in the right direction. I do have mine own module that uses that hook. In case of an offline message, the function sent_notification({Action,Packet} = Acc) gets called. However, I returned with an ok. If I return with Acc., everything seems to work. So I assume I have to pass the input through for the next module (just a guess, I'm not very familiar with ejabberd/erlang). I'm sure my module worked with ejabberd 17.01, when the signature had to be sent_notification(From, To, Packet) and returning with ok. worked. If you provide this as answer, I can accept it. — Christian

Badlop Badlop · Accepted Answer · 2018-05-22T20:40:27

Do you use only the modules included in ejabberd, or did you install any of the contributed, or other custom modules?

Notice that offline_message_hook changed in 17.03 from "run" (without accumulator) to "run_fold" (with accumulator), which means that the result of a function call is passed to the next one, until all finish or one stops the hook.

See commit: https://github.com/processone/ejabberd/commit/e564f9ae31d2c5345be4eed66e70037ba8145dc1 and hook docs: https://docs.ejabberd.im/developer/guide/#hooks

ejabberd: mom_mam throws error

1 Answers