ejabberd: Set mod_mam default to always

This helps various clients to use MAM.

Fixes: #2338

Tests:

- Functional tests for ejabberd pass.

- Install ejabberd and enable MAM. Check that default is set to always
  in the configuration.

- Without this change, install ejabberd and enable MAM. Then restart
  plinth with this change. The configuration is changed from never to
  always. After several minutes, ejabberd is running again.

Signed-off-by: James Valleroy <jvalleroy@mailbox.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>

plinth/modules/ejabberd/__init__.py

@@ -50,7 +50,7 @@ class EjabberdApp(app_module.App):
 
     app_id = 'ejabberd'
 
-    _version = 8
+    _version = 9
 
     def __init__(self) -> None:
         """Create components for the app."""
@@ -159,6 +159,10 @@ class EjabberdApp(app_module.App):
                 'turn-ejabberd').get_configuration()
             update_turn_configuration(configuration, force=True)
 
+        if old_version and old_version < 9 and privileged.mam('status'):
+            # Re-enable to change configuration
+            privileged.mam('enable')
+
 
 class EjabberdTurnConsumer(TurnConsumer):
     """Component to manage Coturn configuration for ejabberd."""

plinth/modules/ejabberd/privileged.py

@@ -261,7 +261,7 @@ def mam(command: str) -> bool | None:
             'mod_mam': {
                 'db_type':
                     'mnesia',  # default is 'mnesia' (w/o set default_db)
-                'default': 'never',  # policy, default 'never'
+                'default': 'always',  # helps various clients to use mam
                 'request_activates_archiving': False,  # default False
                 'assume_mam_usage': False,  # for non-ack'd msgs, default False
                 'cache_size': 1000,  # default is 1000 items