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137 lines
3.3 KiB
Go
137 lines
3.3 KiB
Go
package leaderelection
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import (
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"context"
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"fmt"
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"os"
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"sync/atomic"
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"time"
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"github.com/go-logr/logr"
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"k8s.io/client-go/kubernetes"
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"k8s.io/client-go/tools/leaderelection"
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"k8s.io/client-go/tools/leaderelection/resourcelock"
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)
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const DefaultRetryPeriod = 2 * time.Second
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type Interface interface {
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// Run is a blocking call that runs a leader election
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Run(ctx context.Context)
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// ID returns this instances unique identifier
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ID() string
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// Name returns the name of the leader election
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Name() string
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// Namespace is the Kubernetes namespace used to coordinate the leader election
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Namespace() string
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// IsLeader indicates if this instance is the leader
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IsLeader() bool
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// GetLeader returns the leader ID
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GetLeader() string
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}
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type config struct {
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name string
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namespace string
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startWork func(context.Context)
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stopWork func()
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kubeClient kubernetes.Interface
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lock resourcelock.Interface
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leaderElectionCfg leaderelection.LeaderElectionConfig
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leaderElector *leaderelection.LeaderElector
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isLeader int64
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log logr.Logger
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}
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func New(log logr.Logger, name, namespace string, kubeClient kubernetes.Interface, id string, retryPeriod time.Duration, startWork func(context.Context), stopWork func()) (Interface, error) {
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lock, err := resourcelock.New(
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resourcelock.LeasesResourceLock,
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namespace,
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name,
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kubeClient.CoreV1(),
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kubeClient.CoordinationV1(),
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resourcelock.ResourceLockConfig{
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Identity: id,
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},
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)
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if err != nil {
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return nil, fmt.Errorf("error initializing resource lock: %s/%s: %w", namespace, name, err)
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}
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e := &config{
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name: name,
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namespace: namespace,
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kubeClient: kubeClient,
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lock: lock,
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startWork: startWork,
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stopWork: stopWork,
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log: log.WithValues("id", lock.Identity()),
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}
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e.leaderElectionCfg = leaderelection.LeaderElectionConfig{
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Lock: e.lock,
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ReleaseOnCancel: false,
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LeaseDuration: 6 * retryPeriod,
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RenewDeadline: 5 * retryPeriod,
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RetryPeriod: retryPeriod,
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Callbacks: leaderelection.LeaderCallbacks{
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OnStartedLeading: func(ctx context.Context) {
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atomic.StoreInt64(&e.isLeader, 1)
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e.log.Info("started leading")
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if e.startWork != nil {
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e.startWork(ctx)
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}
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},
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OnStoppedLeading: func() {
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atomic.StoreInt64(&e.isLeader, 0)
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e.log.Info("leadership lost, stopped leading")
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if e.stopWork != nil {
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e.stopWork()
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}
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},
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OnNewLeader: func(identity string) {
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if identity == e.lock.Identity() {
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e.log.Info("still leading")
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} else {
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e.log.Info("another instance has been elected as leader", "leader", identity)
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}
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},
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},
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}
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e.leaderElector, err = leaderelection.NewLeaderElector(e.leaderElectionCfg)
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if err != nil {
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e.log.Error(err, "failed to create leaderElector")
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os.Exit(1)
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}
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if e.leaderElectionCfg.WatchDog != nil {
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e.leaderElectionCfg.WatchDog.SetLeaderElection(e.leaderElector)
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}
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return e, nil
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}
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func (e *config) Name() string {
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return e.name
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}
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func (e *config) Namespace() string {
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return e.namespace
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}
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func (e *config) ID() string {
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return e.lock.Identity()
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}
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func (e *config) IsLeader() bool {
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return atomic.LoadInt64(&e.isLeader) == 1
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}
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func (e *config) GetLeader() string {
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return e.leaderElector.GetLeader()
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}
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func (e *config) Run(ctx context.Context) {
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e.leaderElector.Run(ctx)
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}
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