Adding a package to contain common sidecar flags

config/config.go

@@ -0,0 +1,39 @@
+/*
+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 config
+
+import (
+	"github.com/kubernetes-csi/csi-lib-utils/standardflags"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+)
+
+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()
+}

go.mod

@@ -1,6 +1,6 @@
 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

leaderelection/leader_election.go

@@ -25,10 +25,12 @@ import (
 	"strings"
 	"time"
 
+	"github.com/kubernetes-csi/csi-lib-utils/standardflags"
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/kubernetes/scheme"
 	corev1 "k8s.io/client-go/kubernetes/typed/core/v1"
+	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/leaderelection"
 	"k8s.io/client-go/tools/leaderelection/resourcelock"
 	"k8s.io/client-go/tools/record"
@@ -215,6 +217,58 @@ func (l *leaderElection) Run() error {
 	return nil // should never reach here
 }
 
+func RunWithLeaderElection(
+	ctx context.Context,
+	config *rest.Config,
+	opts standardflags.SidecarConfiguration,
+	run func(context.Context),
+	driverName string,
+	mux *http.ServeMux,
+	releaseOnExit bool) {
+
+	logger := klog.FromContext(ctx)
+
+	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 := NewLeaderElection(leClientset, driverName, run)
+		if opts.HttpEndpoint != "" {
+			le.PrepareHealthCheck(mux, DefaultHealthCheckTimeout)
+		}
+
+		if opts.LeaderElectionNamespace != "" {
+			le.WithNamespace(opts.LeaderElectionNamespace)
+		}
+
+		if opts.LeaderElectionLabels != nil {
+			le.WithLabels(opts.LeaderElectionLabels)
+		}
+
+		le.WithLeaseDuration(opts.LeaderElectionLeaseDuration)
+		le.WithRenewDeadline(opts.LeaderElectionRenewDeadline)
+		le.WithRetryPeriod(opts.LeaderElectionRetryPeriod)
+		if releaseOnExit {
+			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)
+		}
+	}
+}
+
 func defaultLeaderElectionIdentity() (string, error) {
 	return os.Hostname()
 }

standardflags/flags.go

@@ -0,0 +1,83 @@
+/*
+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 standardflags
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+	"time"
+)
+
+type SidecarConfiguration struct {
+	ShowVersion bool
+
+	KubeConfig string
+	CSIAddress string
+
+	LeaderElection              bool
+	LeaderElectionNamespace     string
+	LeaderElectionLeaseDuration time.Duration
+	LeaderElectionRenewDeadline time.Duration
+	LeaderElectionRetryPeriod   time.Duration
+	LeaderElectionLabels        stringMap
+
+	KubeAPIQPS   float64
+	KubeAPIBurst int
+
+	HttpEndpoint   string
+	MetricsAddress string
+	MetricsPath    string
+}
+
+var Configuration = SidecarConfiguration{}
+
+func RegisterCommonFlags(flags *flag.FlagSet) {
+	flags.BoolVar(&Configuration.ShowVersion, "version", false, "Show version.")
+	flags.StringVar(&Configuration.KubeConfig, "kubeconfig", "", "Absolute path to the kubeconfig file. Required only when running out of cluster.")
+	flags.StringVar(&Configuration.CSIAddress, "csi-address", "/run/csi/socket", "The gRPC endpoint for Target CSI Volume.")
+	flags.BoolVar(&Configuration.LeaderElection, "leader-election", false, "Enable leader election.")
+	flags.StringVar(&Configuration.LeaderElectionNamespace, "leader-election-namespace", "", "Namespace where the leader election resource lives. Defaults to the pod namespace if not set.")
+	flags.DurationVar(&Configuration.LeaderElectionLeaseDuration, "leader-election-lease-duration", 15*time.Second, "Duration, in seconds, that non-leader candidates will wait to force acquire leadership. Defaults to 15 seconds.")
+	flags.DurationVar(&Configuration.LeaderElectionRenewDeadline, "leader-election-renew-deadline", 10*time.Second, "Duration, in seconds, that the acting leader will retry refreshing leadership before giving up. Defaults to 10 seconds.")
+	flags.DurationVar(&Configuration.LeaderElectionRetryPeriod, "leader-election-retry-period", 5*time.Second, "Duration, in seconds, the LeaderElector clients should wait between tries of actions. Defaults to 5 seconds.")
+	flags.Var(&Configuration.LeaderElectionLabels, "leader-election-labels", "List of labels to add to lease when given replica becomes leader. Formatted as a comma seperated list of key:value labels. Example: 'my-label:my-value,my-second-label:my-second-value'")
+	flags.Float64Var(&Configuration.KubeAPIQPS, "kube-api-qps", 5, "QPS to use while communicating with the kubernetes apiserver. Defaults to 5.0.")
+	flags.IntVar(&Configuration.KubeAPIBurst, "kube-api-burst", 10, "Burst to use while communicating with the kubernetes apiserver. Defaults to 10.")
+	flags.StringVar(&Configuration.HttpEndpoint, "http-endpoint", "", "The TCP network address where the HTTP server for diagnostics, including metrics and leader election health check, will listen (example: `:8080`). The default is empty string, which means the server is disabled. Only one of `--metrics-address` and `--http-endpoint` can be set.")
+	flags.StringVar(&Configuration.MetricsAddress, "metrics-address", "", "(deprecated) The TCP network address where the prometheus metrics endpoint will listen (example: `:8080`). The default is empty string, which means metrics endpoint is disabled. Only one of `--metrics-address` and `--http-endpoint` can be set.")
+	flag.StringVar(&Configuration.MetricsPath, "metrics-path", "/metrics", "The HTTP path where prometheus metrics will be exposed. Default is `/metrics`.")
+}
+
+type stringMap map[string]string
+
+func (sm *stringMap) String() string {
+	return fmt.Sprintf("%s", *sm)
+}
+
+func (sm *stringMap) Set(value string) error {
+	outMap := *sm
+	items := strings.Split(value, ",")
+	for _, i := range items {
+		label := strings.Split(i, ":")
+		if len(label) != 2 {
+			return fmt.Errorf("malformed item in list of labels: %s", i)
+		}
+		outMap[label[0]] = label[1]
+	}
+	return nil
+}