PR comments

src/charm.py

@@ -252,12 +252,23 @@ def __init__(self, *args):
         self.framework.observe(self.alertmanager_consumer.on.cluster_changed, self._configure)
         self.framework.observe(self.resources_patch.on.patch_failed, self._on_k8s_patch_failed)
         self.framework.observe(self.on.validate_configuration_action, self._on_validate_config)
-        self.framework.observe(self.on.send_datasource_relation_changed, self._configure)
-        self.framework.observe(self.on.send_datasource_relation_departed, self._configure)
-        self.framework.observe(self.on.grafana_source_relation_changed, self._configure)
-        self.framework.observe(self.on.grafana_source_relation_departed, self._configure)
+        self.framework.observe(
+            self.on.send_datasource_relation_changed, self._on_grafana_source_changed
+        )
+        self.framework.observe(
+            self.on.send_datasource_relation_departed, self._on_grafana_source_changed
+        )
+        self.framework.observe(
+            self.on.grafana_source_relation_changed, self._on_grafana_source_changed
+        )
+        self.framework.observe(
+            self.on.grafana_source_relation_departed, self._on_grafana_source_changed
+        )
         self.framework.observe(self.on.collect_unit_status, self._on_collect_unit_status)
 
+    def _on_grafana_source_changed(self, _):
+        self._update_datasource_exchange()
+
     def _on_collect_unit_status(self, event: CollectStatusEvent):
         # "Pull" statuses
         retention_time = self.model.config.get("metrics_retention_time", "")
@@ -586,7 +597,6 @@ def _configure(self, _):
         )
         self.remote_write_provider.update_endpoint()
         self.catalogue.update_item(item=self._catalogue_item)
-        self._update_datasource_exchange()
 
         try:
             # Need to reload if config or alerts changed.
@@ -1122,6 +1132,10 @@ def _update_datasource_exchange(self) -> None:
         if not self.unit.is_leader():
             return
 
+        # we might have multiple grafana-source relations, this method collects them all and returns a mapping from
+        # the `grafana_uid` to the contents of the `datasource_uids` field
+        # for simplicity, we assume that we're sending the same data to different grafanas.
+        # read more in https://discourse.charmhub.io/t/tempo-ha-docs-correlating-traces-metrics-logs/16116
         grafana_uids_to_units_to_uids = self.grafana_source_provider.get_source_uids()
         raw_datasources: List[DatasourceDict] = []
 

tests/integration/helpers.py

@@ -352,7 +352,7 @@ async def deploy_tempo_cluster(ops_test: OpsTest):
             status="active",
             timeout=2000,
             idle_period=30,
-            # TODO: intermittent issue where tempo momentarily goes into error state
+            # TODO: remove when https://github.com/canonical/tempo-coordinator-k8s-operator/issues/90 is fixed
             raise_on_error=False,
         )