feat: add support for disabling alert rules forwarding

charmcraft.yaml

@@ -231,3 +231,8 @@ config:
         Ref (__path_exclude__): https://grafana.com/docs/loki/latest/send-data/promtail/scraping/
       type: string
       default: ""
+    disable_forwarding_alert_rules:
+      description: >
+        Toggle forwarding of alert rules.
+      type: boolean
+      default: false

lib/charms/prometheus_k8s/v1/prometheus_remote_write.py

@@ -46,7 +46,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 5
+LIBPATCH = 6
 
 PYDEPS = ["cosl"]
 
@@ -401,6 +401,7 @@ def __init__(
         charm: CharmBase,
         relation_name: str = DEFAULT_CONSUMER_NAME,
         alert_rules_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH,
+        disable_forwarding_alert_rules: bool = False,
     ):
         """API to manage a required relation with the `prometheus_remote_write` interface.
 
@@ -409,6 +410,7 @@ def __init__(
             relation_name: Name of the relation with the `prometheus_remote_write` interface as
                 defined in metadata.yaml.
             alert_rules_path: Path of the directory containing the alert rules.
+            disable_forwarding_alert_rules: Flag to toggle alert rule forwarding.
 
         Raises:
             RelationNotFoundError: If there is no relation in the charm's metadata.yaml
@@ -437,6 +439,7 @@ def __init__(
         self._charm = charm
         self._relation_name = relation_name
         self._alert_rules_path = alert_rules_path
+        self._disable_alerts = disable_forwarding_alert_rules
 
         self.topology = JujuTopology.from_charm(charm)
 
@@ -453,6 +456,9 @@ def __init__(
         self.framework.observe(
             self._charm.on.upgrade_charm, self._push_alerts_to_all_relation_databags
         )
+        self.framework.observe(
+            self._charm.on.config_changed, self._push_alerts_to_all_relation_databags
+        )
 
     def _on_relation_broken(self, event: RelationBrokenEvent) -> None:
         self.on.endpoints_changed.emit(relation_id=event.relation.id)
@@ -484,11 +490,12 @@ def _push_alerts_to_relation_databag(self, relation: Relation) -> None:
             return
 
         alert_rules = AlertRules(query_type="promql", topology=self.topology)
-        alert_rules.add_path(self._alert_rules_path)
+        if not self._disable_alerts:
+            alert_rules.add_path(self._alert_rules_path)
 
         alert_rules_as_dict = alert_rules.as_dict()
 
-        if alert_rules_as_dict:
+        if alert_rules_as_dict or self._disable_alerts:
             relation.data[self._charm.app]["alert_rules"] = json.dumps(alert_rules_as_dict)
 
     def reload_alerts(self) -> None:

src/grafana_agent.py

@@ -132,6 +132,7 @@ def __init__(self, *args):
         self.status = CompoundStatus()
 
         charm_root = self.charm_dir.absolute()
+        self._disable_alerts = cast(bool, self.config["disable_forwarding_alert_rules"])
         self.loki_rules_paths = RulesMapping(
             # TODO how to inject topology only for this charm's own rules?
             # FIXED: this is already handled by reusing the *Rules classes
@@ -155,8 +156,11 @@ def __init__(self, *args):
                 rules.src.mkdir(parents=True, exist_ok=True)
                 shutil.copytree(rules.src, rules.dest, dirs_exist_ok=True)
 
+        alert_rules_path = self.metrics_rules_paths.dest
         self._remote_write = PrometheusRemoteWriteConsumer(
-            self, alert_rules_path=self.metrics_rules_paths.dest
+            self,
+            alert_rules_path=alert_rules_path,
+            disable_forwarding_alert_rules=self._disable_alerts,
         )
 
         self._loki_consumer = LokiPushApiConsumer(