added grafana uid

lib/charms/grafana_k8s/v0/grafana_source.py

@@ -154,6 +154,8 @@ def __init__(self, *args):
 )
 from ops.model import Relation
 
+from charms.observability_libs.v0.juju_topology import JujuTopology
+
 # The unique Charmhub library identifier, never change it
 LIBID = "974705adb86f40228298156e34b460dc"
 
@@ -162,7 +164,7 @@ def __init__(self, *args):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 23
+LIBPATCH = 24
 
 logger = logging.getLogger(__name__)
 
@@ -432,13 +434,22 @@ def update_source(self, source_url: Optional[str] = ""):
     def get_source_uids(self) -> Dict[str, Dict[str, str]]:
         """Get the datasource UID(s) assigned by the remote end(s) to this datasource.
 
-        Returns a mapping from remote application names to unit names to datasource uids.
+        Returns a mapping from remote application UIDs to unit names to datasource uids.
         """
         uids = {}
         for rel in self._charm.model.relations.get(self._relation_name, []):
             if not rel:
                 continue
-            uids[rel.app.name] = json.loads(rel.data[rel.app].get("datasource_uids", "{}"))
+            app_databag = rel.data[rel.app]
+            grafana_uid = app_databag.get("grafana_uid")
+            if not grafana_uid:
+                logger.warning(
+                    "remote end is using an old grafana_datasource interface: "
+                    "`grafana_uid` field not found."
+                )
+                continue
+
+            uids[grafana_uid] = json.loads(app_databag.get("datasource_uids", "{}"))
         return uids
 
     def _set_sources_from_event(self, event: RelationJoinedEvent) -> None:
@@ -568,6 +579,16 @@ def _publish_source_uids(self, rel: Relation, uids: Dict[str, str]):
 
         Assumes only leader unit will call this method
         """
+        juju_topology = JujuTopology.from_charm(self._charm)
+        unique_grafana_name = "juju_{}_{}_{}_{}".format(
+            juju_topology.model,
+            juju_topology.model_uuid,
+            juju_topology.application,
+            # we inited it from_charm(), so .unit is guaranteed to be set.
+            juju_topology.unit.split("/")[1],  # type: ignore
+        )
+
+        rel.data[self._charm.app]["grafana_uid"] = unique_grafana_name
         rel.data[self._charm.app]["datasource_uids"] = json.dumps(uids)
 
     def _get_source_config(self, rel: Relation):

tests/scenario/test_datasources.py

@@ -42,6 +42,7 @@ def test_datasource_sharing(ctx):
         "remote_host/0": "juju_foo_bar_baz_0",
         "remote_host/1": "juju_foo_bar_baz_1",
     }
+    assert local_app_data["grafana_uid"]
 
 
 def test_datasource_get():
@@ -59,7 +60,10 @@ def test_datasource_get():
                 {"model": "foo", "model_uuid": "bar", "application": "baz", "type": "tempo"}
             )
         },
-        remote_app_data={"datasource_uids": json.dumps(local_ds_uids)},
+        remote_app_data={
+            "grafana_uid": "foo-grafana-1",
+            "datasource_uids": json.dumps(local_ds_uids),
+        },
     )
     state = State(leader=True, relations={datasource})
 
@@ -85,6 +89,7 @@ def __init__(self, framework: Framework):
 
 def test_datasource_get_nodata():
     # GIVEN a datasource relation with two remote units, but which hasn't shared any datasource uids
+    #  for example because the remote end is using an older charm lib
     datasource = Relation(
         "grafana-source",
         remote_app_name="remote_host",
@@ -115,5 +120,5 @@ def __init__(self, framework: Framework):
     ctx = Context(MyProviderCharm, MyProviderCharm.META)
     with ctx(ctx.on.relation_changed(datasource), state) as mgr:
         charm = mgr.charm
-        # THEN we can see our datasource uids via the provider
-        assert list(charm.source_provider.get_source_uids().values())[0] == {}
+        # THEN we can see no datasource uids via the provider
+        assert not charm.source_provider.get_source_uids()