What is Kubernetes Lease objects?

Question

Accepted Answer

**Lease** — lightweight coordination mechanism for distributed systems.

```yaml
apiVersion: coordination.k8s.io/v1
kind: Lease
metadata:
  name: my-app-leader
  namespace: kube-system
spec:
  holderIdentity: "pod-abc123"
  leaseDurationSeconds: 15
  leaseTransitions: 0
  acquireTime: "2024-01-15T10:00:00Z"
  renewTime: "2024-01-15T10:00:15Z"
  strategy: LeaseCandidate
```

```go
// Go example for leader election
import (
    "context"
    "k8s.io/client-go/tools/leaderelection"
    "k8s.io/client-go/tools/leaderelection/resourcelock"
)

lock := &resourcelock.LeaseLock{
    LeasesMeta: metav1.ObjectMeta{
        Name:      "my-app-leader",
        Namespace: "kube-system",
    },
    LockConfig: resourcelock.ResourceLockConfig{
        Identity: hostname,
    },
    Client: clientset.CoordinationV1(),
}

leaderelection.RunOrDie(ctx, leaderelection.LeaderElectionConfig{
    Lock:            lock,
    LeaseDuration:   15 * time.Second,
    RenewDeadline:   10 * time.Second,
    RetryPeriod:     2 * time.Second,
    Callbacks: leaderelection.LeaderCallbacks{
        OnStartedLeading: func(ctx context.Context) {
            // Start controller
        },
        OnStoppedLeading: func() {
            // Cleanup
        },
    },
})
```

**Use cases:**
- Leader election for controllers.
- Distributed locks.
- Node heartbeats.

**vs ConfigMap/Endpoints for locking:**
- Lighter weight.
- Better performance.
- Automatic renewal.

DevOps: What is Kubernetes Lease objects?