refactor: Move leader election logic into csi-lib-utils and genericize

Author: DerekFrank

config/config.go

@@ -0,0 +1,105 @@
+package config
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/kubernetes-csi/csi-lib-utils/features"
+	"github.com/kubernetes-csi/csi-lib-utils/leaderelection"
+	"github.com/kubernetes-csi/csi-lib-utils/metrics"
+	"github.com/kubernetes-csi/csi-lib-utils/standardflags"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/klog/v2"
+)
+
+func BuildConfig(kubeconfig string, opts standardflags.SidecarConfiguration) (*rest.Config, error) {
+	config, err := buildConfig(kubeconfig)
+	if err != nil {
+		return config, err
+	}
+	config.QPS = float32(opts.KubeAPIQPS)
+	config.Burst = opts.KubeAPIBurst
+	return config, nil
+}
+
+
+func buildConfig(kubeconfig string) (*rest.Config, error) {
+	if kubeconfig != "" {
+		return clientcmd.BuildConfigFromFlags("", kubeconfig)
+	}
+	return rest.InClusterConfig()
+}
+
+func RunWithLeaderElection(ctx context.Context, 
+	config *rest.Config, 
+	opts standardflags.SidecarConfiguration, 
+	run func(context.Context), 
+	driverName string, 
+	metricsManager metrics.CSIMetricsManager) {
+	
+	logger := klog.Background()
+	
+	// Prepare http endpoint for metrics + leader election healthz
+	mux := http.NewServeMux()
+	addr := opts.MetricsAddress
+	if addr == "" {
+		addr = opts.HttpEndpoint
+	}
+
+	if addr != "" {
+		metricsManager.RegisterToServer(mux, opts.MetricsPath)
+		metricsManager.SetDriverName(driverName)
+		go func() {
+			logger.Info("ServeMux listening", "address", addr, "metricsPath", opts.MetricsPath)
+			err := http.ListenAndServe(addr, mux)
+			if err != nil {
+				logger.Error(err, "Failed to start HTTP server at specified address and metrics path", "address", addr, "metricsPath", opts.MetricsPath)
+				klog.FlushAndExit(klog.ExitFlushTimeout, 1)
+			}
+		}()
+	}
+	
+	if !opts.LeaderElection {
+		run(klog.NewContext(context.Background(), logger))
+	} else {
+		// Create a new clientset for leader election. When the attacher
+		// gets busy and its client gets throttled, the leader election
+		// can proceed without issues.
+		leClientset, err := kubernetes.NewForConfig(config)
+		if err != nil {
+			logger.Error(err, "Failed to create leaderelection client")
+			klog.FlushAndExit(klog.ExitFlushTimeout, 1)
+		}
+
+		// Name of config map with leader election lock
+		le := leaderelection.NewLeaderElection(leClientset, driverName, run)
+		if opts.HttpEndpoint != "" {
+			le.PrepareHealthCheck(mux, leaderelection.DefaultHealthCheckTimeout)
+		}
+
+		if opts.LeaderElectionNamespace != "" {
+			le.WithNamespace(opts.LeaderElectionNamespace)
+		}
+
+		// TODO: uncomment once https://github.com/kubernetes-csi/csi-lib-utils/pull/200 is merged
+		//if opts.LeaderElectionLabels != nil {
+			// le.WithLabels(opts.LeaderElectionLabels)
+		//}
+
+		le.WithLeaseDuration(opts.LeaderElectionLeaseDuration)
+		le.WithRenewDeadline(opts.LeaderElectionRenewDeadline)
+		le.WithRetryPeriod(opts.LeaderElectionRetryPeriod)
+		if utilfeature.DefaultFeatureGate.Enabled(features.ReleaseLeaderElectionOnExit) {
+			le.WithReleaseOnCancel(true)
+			le.WithContext(ctx)
+		}
+
+		if err := le.Run(); err != nil {
+			logger.Error(err, "Failed to initialize leader election")
+			klog.FlushAndExit(klog.ExitFlushTimeout, 1)
+		}
+	}
+}

features/features.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2025 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 features
+
+import (
+	"k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/component-base/featuregate"
+)
+
+const (
+	// owner: @torredil @gnufied @msau42
+	// kep: https://kep.k8s.io/4876
+	// alpha: v1.33
+	// beta: v1.34
+	//
+	// Makes CSINode.Spec.Drivers[*].Allocatable.Count mutable, allowing CSI drivers to
+	// update the number of volumes that can be allocated on a node. Additionally, enables
+	// setting ErrorCode field in VolumeAttachment status.
+	MutableCSINodeAllocatableCount featuregate.Feature = "MutableCSINodeAllocatableCount"
+
+	// owner: @rhrmo
+	// alpha: v1.34
+	//
+	// Releases leader election lease on sigterm / sigint.
+	ReleaseLeaderElectionOnExit featuregate.Feature = "ReleaseLeaderElectionOnExit"
+)
+
+func init() {
+	feature.DefaultMutableFeatureGate.Add(defaultKubernetesFeatureGates)
+}
+
+// defaultKubernetesFeatureGates consists of all known feature keys specific to external-attacher.
+// To add a new feature, define a key for it above and add it here.
+var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
+	ReleaseLeaderElectionOnExit:    {Default: false, PreRelease: featuregate.Alpha},
+	MutableCSINodeAllocatableCount: {Default: false, PreRelease: featuregate.Beta},
+}
+

go.mod

@@ -1,19 +1,19 @@
 module github.com/kubernetes-csi/csi-lib-utils
 
-go 1.24.0
+go 1.24.6
 
 require (
 	github.com/container-storage-interface/spec v1.11.0
 	github.com/prometheus/client_golang v1.22.0
 	github.com/stretchr/testify v1.10.0
-	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.58.0
-	go.opentelemetry.io/otel/trace v1.33.0
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.60.0
+	go.opentelemetry.io/otel/trace v1.35.0
 	go.uber.org/automaxprocs v1.6.0
-	google.golang.org/grpc v1.69.0
+	google.golang.org/grpc v1.72.1
 	google.golang.org/protobuf v1.36.5
-	k8s.io/api v0.33.1
-	k8s.io/client-go v0.33.1
-	k8s.io/component-base v0.33.1
+	k8s.io/api v0.34.1
+	k8s.io/client-go v0.34.1
+	k8s.io/component-base v0.34.1
 	k8s.io/klog/v2 v2.130.1
 )
 
@@ -22,49 +22,52 @@ require (
 	github.com/blang/semver/v4 v4.0.0 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/emicklei/go-restful/v3 v3.12.1 // indirect
-	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
+	github.com/emicklei/go-restful/v3 v3.12.2 // indirect
+	github.com/fxamacker/cbor/v2 v2.9.0 // indirect
 	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-openapi/jsonpointer v0.21.0 // indirect
 	github.com/go-openapi/jsonreference v0.21.0 // indirect
 	github.com/go-openapi/swag v0.23.0 // indirect
 	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/google/gnostic-models v0.6.9 // indirect
+	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/mailru/easyjson v0.9.0 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
-	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/prometheus/client_model v0.6.1 // indirect
 	github.com/prometheus/common v0.62.0 // indirect
 	github.com/prometheus/procfs v0.15.1 // indirect
-	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/spf13/pflag v1.0.6 // indirect
 	github.com/x448/float16 v0.8.4 // indirect
 	go.opentelemetry.io/auto/sdk v1.1.0 // indirect
-	go.opentelemetry.io/otel v1.33.0 // indirect
-	go.opentelemetry.io/otel/metric v1.33.0 // indirect
+	go.opentelemetry.io/otel v1.35.0 // indirect
+	go.opentelemetry.io/otel/metric v1.35.0 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/net v0.38.0 // indirect
 	golang.org/x/oauth2 v0.27.0 // indirect
 	golang.org/x/sys v0.31.0 // indirect
 	golang.org/x/term v0.30.0 // indirect
 	golang.org/x/text v0.23.0 // indirect
 	golang.org/x/time v0.9.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20241216192217-9240e9c98484 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20250303144028-a0af3efb3deb // indirect
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
-	k8s.io/apimachinery v0.33.1 // indirect
-	k8s.io/kube-openapi v0.0.0-20250318190949-c8a335a9a2ff // indirect
-	k8s.io/utils v0.0.0-20241210054802-24370beab758 // indirect
+	k8s.io/apimachinery v0.34.1 // indirect
+	k8s.io/apiserver v0.34.1
+	k8s.io/kube-openapi v0.0.0-20250710124328-f3f2b991d03b // indirect
+	k8s.io/utils v0.0.0-20250604170112-4c0f3b243397 // indirect
 	sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8 // indirect
 	sigs.k8s.io/randfill v1.0.0 // indirect
-	sigs.k8s.io/structured-merge-diff/v4 v4.6.0 // indirect
-	sigs.k8s.io/yaml v1.4.0 // indirect
+	sigs.k8s.io/structured-merge-diff/v6 v6.3.0 // indirect
+	sigs.k8s.io/yaml v1.6.0 // indirect
 )