miniflux: Add management of postgresql daemon in a shared manner

- This allows miniflux to disabled postgresql if it is not needed by any other
app and enable postgresql if it is disabled and miniflux is being enabled.

Tests:

- When disabling miniflux and it is the last app using postgresql, it will be
disabled too.

- When disabling miniflux and it is not the last app using postgresql, it will
not be disabled too.

- When enabling miniflux if postgresql is disabled, it will be enabled too.

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

plinth/modules/miniflux/__init__.py

@@ -6,7 +6,7 @@ from django.utils.translation import gettext_lazy as _
 from plinth import app as app_module
 from plinth import frontpage, menu
 from plinth.config import DropinConfigs
-from plinth.daemon import Daemon
+from plinth.daemon import Daemon, SharedDaemon
 from plinth.modules.apache.components import Webserver
 from plinth.modules.backups.components import BackupRestore
 from plinth.modules.firewall.components import Firewall
@@ -74,6 +74,10 @@ class MinifluxApp(app_module.App):
                               urls=['https://{host}/miniflux/'])
         self.add(webserver)
 
+        daemon = SharedDaemon('shared-daemon-miniflus-postgresql',
+                              'postgresql')
+        self.add(daemon)
+
         daemon = Daemon('daemon-miniflux', 'miniflux',
                         listen_ports=[(8788, 'tcp4'), (8788, 'tcp6')])
         self.add(daemon)