Emit the node group metrics behind a flag

cluster-autoscaler/core/scale_up_test.go

@@ -978,7 +978,7 @@ func TestCheckScaleUpDeltaWithinLimits(t *testing.T) {
 }
 
 func TestAuthError(t *testing.T) {
-	metrics.RegisterAll()
+	metrics.RegisterAll(false)
 	context, err := NewScaleTestAutoscalingContext(config.AutoscalingOptions{}, &fake.Clientset{}, nil, nil, nil)
 	assert.NoError(t, err)
 

cluster-autoscaler/main.go

@@ -179,6 +179,8 @@ var (
 	cordonNodeBeforeTerminate          = flag.Bool("cordon-node-before-terminating", false, "Should CA cordon nodes before terminating during downscale process")
 	daemonSetEvictionForEmptyNodes     = flag.Bool("daemonset-eviction-for-empty-nodes", false, "DaemonSet pods will be gracefully terminated from empty nodes")
 	userAgent                          = flag.String("user-agent", "cluster-autoscaler", "User agent used for HTTP calls.")
+
+	emitPerNodeGroupMetrics = flag.Bool("emit-per-nodegroup-metrics", false, "If true, emit per node group metrics.")
 )
 
 func createAutoscalingOptions() config.AutoscalingOptions {
@@ -340,7 +342,7 @@ func buildAutoscaler() (core.Autoscaler, error) {
 }
 
 func run(healthCheck *metrics.HealthCheck) {
-	metrics.RegisterAll()
+	metrics.RegisterAll(*emitPerNodeGroupMetrics)
 
 	autoscaler, err := buildAutoscaler()
 	if err != nil {

cluster-autoscaler/metrics/metrics.go

@@ -330,7 +330,7 @@ var (
 )
 
 // RegisterAll registers all metrics.
-func RegisterAll() {
+func RegisterAll(emitPerNodeGroupMetrics bool) {
 	legacyregistry.MustRegister(clusterSafeToAutoscale)
 	legacyregistry.MustRegister(nodesCount)
 	legacyregistry.MustRegister(nodeGroupsCount)
@@ -340,8 +340,6 @@ func RegisterAll() {
 	legacyregistry.MustRegister(cpuLimitsCores)
 	legacyregistry.MustRegister(memoryCurrentBytes)
 	legacyregistry.MustRegister(memoryLimitsBytes)
-	legacyregistry.MustRegister(nodesGroupMinNodes)
-	legacyregistry.MustRegister(nodesGroupMaxNodes)
 	legacyregistry.MustRegister(lastActivity)
 	legacyregistry.MustRegister(functionDuration)
 	legacyregistry.MustRegister(functionDurationSummary)
@@ -359,6 +357,11 @@ func RegisterAll() {
 	legacyregistry.MustRegister(napEnabled)
 	legacyregistry.MustRegister(nodeGroupCreationCount)
 	legacyregistry.MustRegister(nodeGroupDeletionCount)
+
+	if emitPerNodeGroupMetrics {
+		legacyregistry.MustRegister(nodesGroupMinNodes)
+		legacyregistry.MustRegister(nodesGroupMaxNodes)
+	}
 }
 
 // UpdateDurationFromStart records the duration of the step identified by the

cluster-autoscaler/metrics/metrics_test.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2021 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metrics
+
+import (
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus/testutil"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDisabledPerNodeGroupMetrics(t *testing.T) {
+	RegisterAll(false)
+	assert.False(t, nodesGroupMinNodes.IsCreated())
+	assert.False(t, nodesGroupMaxNodes.IsCreated())
+}
+
+func TestEnabledPerNodeGroupMetrics(t *testing.T) {
+	RegisterAll(true)
+	assert.True(t, nodesGroupMinNodes.IsCreated())
+	assert.True(t, nodesGroupMaxNodes.IsCreated())
+
+	UpdateNodeGroupMin("foo", 2)
+	UpdateNodeGroupMax("foo", 100)
+
+	assert.Equal(t, 2, int(testutil.ToFloat64(nodesGroupMinNodes.GaugeVec.WithLabelValues("foo"))))
+	assert.Equal(t, 100, int(testutil.ToFloat64(nodesGroupMaxNodes.GaugeVec.WithLabelValues("foo"))))
+}