Alerting: Fix attachment of external labels to Loki state history log streams (#65140)

Fix attachment of external labels, add tests

pkg/services/ngalert/state/historian/loki_http.go

@@ -74,6 +74,7 @@ func NewLokiConfig(cfg setting.UnifiedAlertingStateHistorySettings) (LokiConfig,
 		BasicAuthUser:     cfg.LokiBasicAuthUsername,
 		BasicAuthPassword: cfg.LokiBasicAuthPassword,
 		TenantID:          cfg.LokiTenantID,
+		ExternalLabels:    cfg.ExternalLabels,
 		// Snappy-compressed protobuf is the default, same goes for Promtail.
 		Encoder: SnappyProtoEncoder{},
 	}, nil

pkg/services/ngalert/state/historian/loki_http_test.go

@@ -77,6 +77,18 @@ func TestLokiConfig(t *testing.T) {
 			})
 		}
 	})
+
+	t.Run("captures external labels", func(t *testing.T) {
+		set := setting.UnifiedAlertingStateHistorySettings{
+			LokiRemoteURL:  "http://url.com",
+			ExternalLabels: map[string]string{"a": "b"},
+		}
+
+		res, err := NewLokiConfig(set)
+
+		require.NoError(t, err)
+		require.Contains(t, res.ExternalLabels, "a")
+	})
 }
 
 func TestLokiHTTPClient(t *testing.T) {

pkg/services/ngalert/state/historian/loki_test.go

@@ -346,14 +346,32 @@ grafana_alerting_state_history_writes_total{org="1"} 2
 		require.Contains(t, sent, "contains=equals")
 		require.Contains(t, sent, "contains🤔emoji")
 	})
+
+	t.Run("adds external labels to log lines", func(t *testing.T) {
+		req := NewFakeRequester()
+		loki := createTestLokiBackend(req, metrics.NewHistorianMetrics(prometheus.NewRegistry()))
+		rule := createTestRule()
+		states := singleFromNormal(&state.State{
+			State: eval.Alerting,
+		})
+
+		err := <-loki.Record(context.Background(), rule, states)
+
+		require.NoError(t, err)
+		require.Contains(t, "/loki/api/v1/push", req.lastRequest.URL.Path)
+		sent := string(readBody(t, req.lastRequest))
+		require.Contains(t, sent, "externalLabelKey")
+		require.Contains(t, sent, "externalLabelValue")
+	})
 }
 
 func createTestLokiBackend(req client.Requester, met *metrics.Historian) *RemoteLokiBackend {
 	url, _ := url.Parse("http://some.url")
 	cfg := LokiConfig{
-		WritePathURL: url,
-		ReadPathURL:  url,
-		Encoder:      JsonEncoder{},
+		WritePathURL:   url,
+		ReadPathURL:    url,
+		Encoder:        JsonEncoder{},
+		ExternalLabels: map[string]string{"externalLabelKey": "externalLabelValue"},
 	}
 	return NewRemoteLokiBackend(cfg, req, met)
 }