chore(unified-storage): add dual writer metric to track instance modes (#105144)

pkg/services/apiserver/builder/helper.go

@@ -298,6 +298,7 @@ func InstallAPIs(
 	// this is needed to support setting a default RESTOptionsGetter for new APIs that don't
 	// support the legacy storage type.
 	var dualWrite grafanarest.DualWriteBuilder
+	metrics := newBuilderMetrics(reg)
 
 	// nolint:staticcheck
 	if storageOpts.StorageType != options.StorageTypeLegacy {
@@ -359,6 +360,9 @@ func InstallAPIs(
 			if err != nil {
 				return nil, err
 			}
+
+			metrics.recordDualWriterModes(gr.Resource, gr.Group, mode, currentMode)
+
 			switch currentMode {
 			case grafanarest.Mode0:
 				return legacy, nil
@@ -366,6 +370,7 @@ func InstallAPIs(
 				return storage, nil
 			default:
 			}
+
 			if dualWriterPeriodicDataSyncJobEnabled {
 				// The mode might have changed in SetDualWritingMode, so apply current mode first.
 				syncerCfg.Mode = currentMode

pkg/services/apiserver/builder/metrics.go

@@ -0,0 +1,30 @@
+package builder
+
+import (
+	grafanarest "github.com/grafana/grafana/pkg/apiserver/rest"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
+)
+
+type builderMetrics struct {
+	dualWriterTargetMode  *prometheus.GaugeVec
+	dualWriterCurrentMode *prometheus.GaugeVec
+}
+
+func newBuilderMetrics(reg prometheus.Registerer) *builderMetrics {
+	return &builderMetrics{
+		dualWriterTargetMode: promauto.With(reg).NewGaugeVec(prometheus.GaugeOpts{
+			Name: "unified_storage_dual_writer_target_mode",
+			Help: "Unified Storage dual writer target mode",
+		}, []string{"resource", "group"}),
+		dualWriterCurrentMode: promauto.With(reg).NewGaugeVec(prometheus.GaugeOpts{
+			Name: "unified_storage_dual_writer_current_mode",
+			Help: "Unified storage dual writer current mode",
+		}, []string{"resource", "group"}),
+	}
+}
+
+func (m *builderMetrics) recordDualWriterModes(resource, group string, targetMode, currentMode grafanarest.DualWriterMode) {
+	m.dualWriterTargetMode.WithLabelValues(resource, group).Set(float64(targetMode))
+	m.dualWriterCurrentMode.WithLabelValues(resource, group).Set(float64(currentMode))
+}

pkg/services/apiserver/service.go

@@ -27,7 +27,6 @@ import (
 	"github.com/grafana/grafana/pkg/infra/db"
 	"github.com/grafana/grafana/pkg/infra/kvstore"
 	"github.com/grafana/grafana/pkg/infra/log"
-	"github.com/grafana/grafana/pkg/infra/metrics"
 	"github.com/grafana/grafana/pkg/infra/serverlock"
 	"github.com/grafana/grafana/pkg/infra/tracing"
 	"github.com/grafana/grafana/pkg/middleware"
@@ -122,6 +121,7 @@ func ProvideService(
 	restConfigProvider RestConfigProvider,
 	buildHandlerChainFuncFromBuilders builder.BuildHandlerChainFuncFromBuilders,
 	eventualRestConfigProvider *eventualRestConfigProvider,
+	reg prometheus.Registerer,
 ) (*service, error) {
 	scheme := builder.ProvideScheme()
 	codecs := builder.ProvideCodecFactory(scheme)
@@ -137,7 +137,7 @@ func ProvideService(
 		authorizer:                        authorizer.NewGrafanaAuthorizer(cfg),
 		tracing:                           tracing,
 		db:                                db, // For Unified storage
-		metrics:                           metrics.ProvideRegisterer(),
+		metrics:                           reg,
 		kvStore:                           kvStore,
 		pluginClient:                      pluginClient,
 		datasources:                       datasources,