Alerting: Attach hash of instance labels to state history log lines (#65968)

* Add instanceID which is hash of labels

* Rename field to fingerprint

* Move to prometheus style signature

* Appease linter

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

@@ -1,10 +1,12 @@
 package historian
 
 import (
+	"fmt"
 	"strings"
 	"time"
 
 	"github.com/grafana/grafana-plugin-sdk-go/data"
+	prometheus "github.com/prometheus/common/model"
 
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/services/ngalert/eval"
@@ -42,6 +44,12 @@ func removePrivateLabels(labels data.Labels) data.Labels {
 	return result
 }
 
+// labelFingerprint calculates a stable Prometheus-style signature for a label set.
+func labelFingerprint(labels data.Labels) string {
+	sig := prometheus.LabelsToSignature(labels)
+	return fmt.Sprintf("%016x", sig)
+}
+
 // panelKey uniquely identifies a panel.
 type panelKey struct {
 	orgID   int64

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

@@ -255,6 +255,7 @@ func statesToStream(rule history_model.RuleMeta, states []state.StateTransition,
 			continue
 		}
 
+		sanitizedLabels := removePrivateLabels(state.Labels)
 		entry := lokiEntry{
 			SchemaVersion:  1,
 			Previous:       state.PreviousFormatted(),
@@ -263,7 +264,8 @@ func statesToStream(rule history_model.RuleMeta, states []state.StateTransition,
 			Condition:      rule.Condition,
 			DashboardUID:   rule.DashboardUID,
 			PanelID:        rule.PanelID,
-			InstanceLabels: removePrivateLabels(state.Labels),
+			Fingerprint:    labelFingerprint(sanitizedLabels),
+			InstanceLabels: sanitizedLabels,
 		}
 		if state.State.State == eval.Error {
 			entry.Error = state.Error.Error()
@@ -306,6 +308,7 @@ type lokiEntry struct {
 	Condition     string           `json:"condition"`
 	DashboardUID  string           `json:"dashboardUID"`
 	PanelID       int64            `json:"panelID"`
+	Fingerprint   string           `json:"fingerprint"`
 	// InstanceLabels is exactly the set of labels associated with the alert instance in Alertmanager.
 	// These should not be conflated with labels associated with log streams.
 	InstanceLabels map[string]string `json:"labels"`

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

@@ -154,6 +154,25 @@ func TestRemoteLokiBackend(t *testing.T) {
 			entry := requireSingleEntry(t, res)
 			require.Equal(t, rule.Condition, entry.Condition)
 		})
+
+		t.Run("stores fingerprint of instance labels", func(t *testing.T) {
+			rule := createTestRule()
+			l := log.NewNopLogger()
+			states := singleFromNormal(&state.State{
+				State: eval.Alerting,
+				Labels: data.Labels{
+					"statelabel": "labelvalue",
+					"labeltwo":   "labelvalue",
+					"labelthree": "labelvalue",
+				},
+			})
+
+			res := statesToStream(rule, states, nil, l)
+
+			entry := requireSingleEntry(t, res)
+			exp := labelFingerprint(states[0].Labels)
+			require.Equal(t, exp, entry.Fingerprint)
+		})
 	})
 
 	t.Run("selector string", func(t *testing.T) {