Add central logic to check obj layer initialized

cmd/metrics-v3-cluster-config.go

@@ -42,10 +42,8 @@ func loadClusterConfigMetrics(ctx context.Context, m MetricValues, c *metricsCac
 	m.Set(configRRSParity, float64(clusterDriveMetrics.storageInfo.Backend.RRSCParity))
 
 	objLayer := newObjectLayerFn()
-	if objLayer != nil {
-		result := objLayer.Health(ctx, HealthOptions{})
-		m.Set(configWriteQuorum, float64(result.WriteQuorum))
-	}
+	result := objLayer.Health(ctx, HealthOptions{})
+	m.Set(configWriteQuorum, float64(result.WriteQuorum))
 
 	return nil
 }

cmd/metrics-v3-types.go

@@ -358,6 +358,9 @@ type MetricsGroup struct {
 	// Collect() call. This is protected by the `bucketsLock`.
 	bucketsLock sync.Mutex
 	buckets     []string
+
+	// metricsGroupOpts - options for the metrics group.
+	metricsGroupOpts MetricsGroupOpts
 }
 
 // NewMetricsGroup creates a new MetricsGroup. To create a metrics group for
@@ -408,6 +411,14 @@ func (mg *MetricsGroup) AddExtraLabels(labels ...string) {
 	}
 }
 
+// requiresObjectLayer - use to add dependency on the global object layer API
+// when creating the metrics group
+// e.g. myMG := NewMetricsGroup(...).requiresObjectLayer()
+func (mg *MetricsGroup) requiresObjectLayer(labels ...string) *MetricsGroup {
+	mg.metricsGroupOpts.dependGlobalObjectAPI = true
+	return mg
+}
+
 // IsBucketMetricsGroup - returns true if the given MetricsGroup is a bucket
 // metrics group.
 func (mg *MetricsGroup) IsBucketMetricsGroup() bool {
@@ -421,6 +432,10 @@ func (mg *MetricsGroup) Describe(ch chan<- *prometheus.Desc) {
 	}
 }
 
+func isObjectLayerInitialized() bool {
+	return newObjectLayerFn() != nil
+}
+
 // Collect - implements prometheus.Collector interface.
 func (mg *MetricsGroup) Collect(ch chan<- prometheus.Metric) {
 	metricValues := newMetricValues(mg.descriptorMap)
@@ -429,7 +444,13 @@ func (mg *MetricsGroup) Collect(ch chan<- prometheus.Metric) {
 	if mg.IsBucketMetricsGroup() {
 		err = mg.bucketLoader(GlobalContext, metricValues, mg.cache, mg.buckets)
 	} else {
-		err = mg.loader(GlobalContext, metricValues, mg.cache)
+		canLoad := true
+		if mg.metricsGroupOpts.dependGlobalObjectAPI && !isObjectLayerInitialized() {
+			canLoad = false
+		}
+		if canLoad {
+			err = mg.loader(GlobalContext, metricValues, mg.cache)
+		}
 	}
 
 	// There is no way to handle errors here, so we panic the current goroutine

cmd/metrics-v3.go

@@ -286,7 +286,7 @@ func newMetricGroups(r *prometheus.Registry) *metricsV3Collection {
 			configStandardParityMD,
 		},
 		loadClusterConfigMetrics,
-	)
+	).requiresObjectLayer()
 
 	allMetricGroups := []*MetricsGroup{
 		apiRequestsMG,