---
title: Leases
content_type: concept
weight: 30
---

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Distributed systems often have a need for _leases_, which provide a mechanism to lock shared resources
and coordinate activity between members of a set.
In Kubernetes, the lease concept is represented by [Lease](/docs/reference/kubernetes-api/cluster-resources/lease-v1/)
objects in the `coordination.k8s.io` {{< glossary_tooltip text="API Group" term_id="api-group" >}},
which are used for system-critical capabilities such as node heartbeats and component-level leader election.

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## Node heartbeats {#node-heart-beats}

Kubernetes uses the Lease API to communicate kubelet node heartbeats to the Kubernetes API server.
For every `Node` , there is a `Lease` object with a matching name in the `kube-node-lease`
namespace. Under the hood, every kubelet heartbeat is an **update** request to this `Lease` object, updating
the `spec.renewTime` field for the Lease. The Kubernetes control plane uses the time stamp of this field
to determine the availability of this `Node`.

See [Node Lease objects](/docs/concepts/architecture/nodes/#heartbeats) for more details.

## Leader election

Kubernetes also uses Leases to ensure only one instance of a component is running at any given time.
This is used by control plane components like `kube-controller-manager` and `kube-scheduler` in
HA configurations, where only one instance of the component should be actively running while the other
instances are on stand-by.

## API server identity

{{< feature-state feature_gate_name="APIServerIdentity" >}}

Starting in Kubernetes v1.26, each `kube-apiserver` uses the Lease API to publish its identity to the
rest of the system. While not particularly useful on its own, this provides a mechanism for clients to
discover how many instances of `kube-apiserver` are operating the Kubernetes control plane.
Existence of kube-apiserver leases enables future capabilities that may require coordination between
each kube-apiserver.

You can inspect Leases owned by each kube-apiserver by checking for lease objects in the `kube-system` namespace
with the name `kube-apiserver-<sha256-hash>`. Alternatively you can use the label selector `apiserver.kubernetes.io/identity=kube-apiserver`:

```shell
kubectl -n kube-system get lease -l apiserver.kubernetes.io/identity=kube-apiserver
```
```
NAME                                        HOLDER                                                                           AGE
apiserver-07a5ea9b9b072c4a5f3d1c3702        apiserver-07a5ea9b9b072c4a5f3d1c3702_0c8914f7-0f35-440e-8676-7844977d3a05        5m33s
apiserver-7be9e061c59d368b3ddaf1376e        apiserver-7be9e061c59d368b3ddaf1376e_84f2a85d-37c1-4b14-b6b9-603e62e4896f        4m23s
apiserver-1dfef752bcb36637d2763d1868        apiserver-1dfef752bcb36637d2763d1868_c5ffa286-8a9a-45d4-91e7-61118ed58d2e        4m43s

```

The SHA256 hash used in the lease name is based on the OS hostname as seen by that API server. Each kube-apiserver should be
configured to use a hostname that is unique within the cluster. New instances of kube-apiserver that use the same hostname
will take over existing Leases using a new holder identity, as opposed to instantiating new Lease objects. You can check the
hostname used by kube-apisever by checking the value of the `kubernetes.io/hostname` label:

```shell
kubectl -n kube-system get lease apiserver-07a5ea9b9b072c4a5f3d1c3702 -o yaml
```
```yaml
apiVersion: coordination.k8s.io/v1
kind: Lease
metadata:
  creationTimestamp: "2023-07-02T13:16:48Z"
  labels:
    apiserver.kubernetes.io/identity: kube-apiserver
    kubernetes.io/hostname: master-1
  name: apiserver-07a5ea9b9b072c4a5f3d1c3702
  namespace: kube-system
  resourceVersion: "334899"
  uid: 90870ab5-1ba9-4523-b215-e4d4e662acb1
spec:
  holderIdentity: apiserver-07a5ea9b9b072c4a5f3d1c3702_0c8914f7-0f35-440e-8676-7844977d3a05
  leaseDurationSeconds: 3600
  renewTime: "2023-07-04T21:58:48.065888Z"
```

Expired leases from kube-apiservers that no longer exist are garbage collected by new kube-apiservers after 1 hour.

You can disable API server identity leases by disabling the `APIServerIdentity`
[feature gate](/docs/reference/command-line-tools-reference/feature-gates/).

## Workloads {#custom-workload}

Your own workload can define its own use of Leases. For example, you might run a custom
{{< glossary_tooltip term_id="controller" text="controller" >}} where a primary or leader member
performs operations that its peers do not. You define a Lease so that the controller replicas can select
or elect a leader, using the Kubernetes API for coordination.
If you do use a Lease, it's a good practice to define a name for the Lease that is obviously linked to
the product or component. For example, if you have a component named Example Foo, use a Lease named
`example-foo`.

If a cluster operator or another end user could deploy multiple instances of a component, select a name
prefix and pick a mechanism (such as hash of the name of the Deployment) to avoid name collisions
for the Leases.

You can use another approach so long as it achieves the same outcome: different software products do
not conflict with one another.