[DPE-8550] Check juju version before removing revision

src/charm.py

@@ -62,7 +62,7 @@
 from lightkube.models.core_v1 import ServicePort, ServiceSpec
 from lightkube.models.meta_v1 import ObjectMeta
 from lightkube.resources.core_v1 import Endpoints, Node, Pod, Service
-from ops import main
+from ops import JujuVersion, main
 from ops.charm import (
     ActionEvent,
     HookEvent,
@@ -1365,6 +1365,12 @@ def promote_primary_unit(self, event: ActionEvent) -> None:
                 event.fail("Switchover failed or timed out, check the logs for details")
 
     def _on_secret_remove(self, event: SecretRemoveEvent) -> None:
+        if self.model.juju_version < JujuVersion("3.6.11"):
+            logger.warning(
+                "Skipping secret revision removal due to https://github.com/juju/juju/issues/20782"
+            )
+            return
+
         # A secret removal (entire removal, not just a revision removal) causes
         # https://github.com/juju/juju/issues/20794. This check is to avoid the
         # errors that would happen if we tried to remove the revision in that case

tests/unit/test_charm.py

@@ -11,6 +11,7 @@
 from charms.postgresql_k8s.v0.postgresql import PostgreSQLUpdateUserPasswordError
 from lightkube import ApiError
 from lightkube.resources.core_v1 import Endpoints, Pod, Service
+from ops import JujuVersion
 from ops.model import (
     ActiveStatus,
     BlockedStatus,
@@ -1905,13 +1906,25 @@ def test_get_ldap_parameters(harness):
         _get_relation_data.reset_mock()
 
 
-def test_on_secret_remove(harness):
-    event = Mock()
-    harness.charm._on_secret_remove(event)
-    event.remove_revision.assert_called_once_with()
-    event.reset_mock()
+def test_on_secret_remove(harness, only_with_juju_secrets):
+    with (
+        patch("ops.model.Model.juju_version", new_callable=PropertyMock) as _juju_version,
+    ):
+        event = Mock()
 
-    # No secret
-    event.secret.label = None
-    harness.charm._on_secret_remove(event)
-    assert not event.remove_revision.called
+        # New juju
+        _juju_version.return_value = JujuVersion("3.6.11")
+        harness.charm._on_secret_remove(event)
+        event.remove_revision.assert_called_once_with()
+        event.reset_mock()
+
+        # Old juju
+        _juju_version.return_value = JujuVersion("3.6.9")
+        harness.charm._on_secret_remove(event)
+        assert not event.remove_revision.called
+        event.reset_mock()
+
+        # No secret
+        event.secret.label = None
+        harness.charm._on_secret_remove(event)
+        assert not event.remove_revision.called