fix: configure prometheus_remote_write config for non-leader

lib/charms/grafana_cloud_integrator/v0/cloud_config_requirer.py

@@ -57,7 +57,7 @@ def _on_relation_changed(self, event):
 
     def _on_relation_broken(self, event):
         self.on.cloud_config_revoked.emit()  # pyright: ignore
-    
+
     def _is_not_empty(self, s):
         return bool(s and not s.isspace())
 
@@ -124,7 +124,7 @@ def prometheus_endpoint(self) -> dict:
         """Return the prometheus endpoint dict."""
         if not self.prometheus_ready:
             return {}
-        
+
         endpoint = {}
         endpoint["url"] = self.prometheus_url
         if self.credentials:

tests/unit/test_cloud_integration.py

@@ -0,0 +1,65 @@
+import tempfile
+import unittest
+from pathlib import Path
+from unittest.mock import patch
+
+import yaml
+from ops import ActiveStatus, BlockedStatus
+from ops.testing import Harness
+
+from charm import GrafanaAgentMachineCharm as GrafanaAgentCharm
+
+
+class TestUpdateStatus(unittest.TestCase):
+    def setUp(self, *unused):
+        patcher = patch.object(GrafanaAgentCharm, "_agent_version", property(lambda *_: "0.0.0"))
+        self.mock_version = patcher.start()
+        self.addCleanup(patcher.stop)
+
+        temp_config_path = tempfile.mkdtemp() + "/grafana-agent.yaml"
+        # otherwise will attempt to write to /etc/grafana-agent.yaml
+        patcher = patch("grafana_agent.CONFIG_PATH", temp_config_path)
+        self.config_path_mock = patcher.start()
+        self.addCleanup(patcher.stop)
+
+        patcher = patch("charm.snap")
+        self.mock_snap = patcher.start()
+        self.addCleanup(patcher.stop)
+
+        patcher = patch.object(GrafanaAgentCharm, "_install")
+        self.mock_install = patcher.start()
+        self.addCleanup(patcher.stop)
+
+    def test_prometheus_remote_write_config_with_grafana_cloud_integrator(self):
+        """Asserts that the prometheus remote write config is written correctly for leaders and non-leaders."""
+        for leader in (True, False):
+            with self.subTest(leader=leader):
+                harness = Harness(GrafanaAgentCharm)
+                harness.set_model_name(self.__class__.__name__)
+                harness.set_leader(True)
+                harness.begin_with_initial_hooks()
+
+                # WHEN an incoming relation is added
+                rel_id = harness.add_relation("juju-info", "grafana-agent")
+                harness.add_relation_unit(rel_id, "grafana-agent/0")
+
+                # THEN the charm goes into blocked status
+                assert isinstance(harness.charm.unit.status, BlockedStatus)
+
+                # AND WHEN the necessary outgoing relations are added
+                harness.add_relation(
+                    "grafana-cloud-config",
+                    "grafana-cloud-integrator",
+                    app_data={"prometheus_url": "http://some.domain.name:9090/api/v1/write"},
+                )
+
+                # THEN the charm goes into active status
+                assert isinstance(harness.charm.unit.status, ActiveStatus)
+
+                # THEN with the expected prometheus endpoint settings are written to the config file
+                config = yaml.safe_load(Path(self.config_path_mock).read_text())
+                assert len(config["integrations"]["prometheus_remote_write"]) == 1
+                self.assertEqual(
+                    config["integrations"]["prometheus_remote_write"][0]["url"],
+                    "http://some.domain.name:9090/api/v1/write",
+                )