Merge ~jk0ne/charm-k8s-discourse/+git/charm-k8s-discourse:master into charm-k8s-discourse:master

[Jay Kuri]

Bring in updates made as part of charmcraft review

[Jay Kuri (jk0ne)]

Self approved per Tom as this has already passed charmcraft-review

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change cannot be self approved, setting status to needs review.

[Gareth Woolridge (moon127)]

LGTM

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 7e73fc91c771eb031ce47ff72e63d7bbe23a4a2b

diff --git a/src/charm.py b/src/charm.py
index bb33602..5bb75ad 100755
--- a/src/charm.py
+++ b/src/charm.py
@@ -138,7 +138,7 @@ def check_for_missing_config_fields(config):
         'external_hostname',
     ]
     for key in needed_fields:
-        if (config.get(key) is None) or (len(config[key]) == 0):
+        if not config.get(key):
             missing_fields.append(key)
 
     return sorted(missing_fields)
@@ -228,7 +228,13 @@ class DiscourseCharm(CharmBase):
         # Per https://github.com/canonical/ops-lib-pgsql/issues/2,
         # changing the setting in the config will not take effect,
         # unless the relation is dropped and recreated.
-        event.database = self.model.config["db_name"]
+        if self.model.unit.is_leader():
+            event.database = self.model.config["db_name"]
+        elif event.database != self.model.config["db_name"]:
+            # Leader has not yet set requirements. Defer, in case this unit
+            # becomes leader and needs to perform that operation.
+            event.defer()
+            return
 
     def on_database_changed(self, event):
         """Event handler for database relation change.
diff --git a/tests/unit/test_charm.py b/tests/unit/test_charm.py
index 214bfa1..8dc65d8 100644
--- a/tests/unit/test_charm.py
+++ b/tests/unit/test_charm.py
@@ -114,3 +114,22 @@ class TestDiscourseK8sCharmHooksDisabled(unittest.TestCase):
         self.harness.charm.on_database_changed(db_event)
         configured_spec = self.harness.get_pod_spec()
         self.assertEqual(configured_spec, None, 'Lost DB relation does not result in empty spec as expected')
+
+    def test_on_database_relation_joined(self):
+        """Test joining the DB relation."""
+        # First test with a non-leader, confirm the database property isn't set.
+        non_leader_harness = testing.Harness(DiscourseCharm)
+        non_leader_harness.disable_hooks()
+        non_leader_harness.set_leader(False)
+        non_leader_harness.begin()
+
+        action_event = mock.Mock()
+        action_event.database = None
+        non_leader_harness.update_config(self.configs['config_valid_complete']['config'])
+        non_leader_harness.charm.on_database_relation_joined(action_event)
+        self.assertEqual(action_event.database, None)
+
+        # Now test with a leader, the database property is set.
+        self.harness.update_config(self.configs['config_valid_complete']['config'])
+        self.harness.charm.on_database_relation_joined(action_event)
+        self.assertEqual(action_event.database, "discourse")