open-consul/website/content/docs/connect/cluster-peering/k8s.mdx

---
layout: docs
page_title: Cluster Peering on Kubernetes
description: >-
  This page describes how to create peering connections, deploy services, export cluster services, and end peering connections for Consul cluster peering using Kubernetes (K8s).
---

# Cluster Peering on Kubernetes

~> **Cluster peering is currently in beta:** Functionality associated
with cluster peering is subject to change. You should never use the beta release in secure environments or production scenarios. Features in
beta may have performance issues, scaling issues, and limited support.<br/><br/>Cluster peering is not currently available in the HCP Consul offering.

To establish a cluster peering connection on Kubernetes, you need to enable the feature in the Helm chart and create custom resource definitions (CRDs) for each side of the peering.

The following CRDs are used to create and manage a peering connection:

- `PeeringAcceptor`: Generates a peering token and accepts an incoming peering connection.
- `PeeringDialer`: Uses a peering token to make an outbound peering connection with the cluster that generated the token.

## Prerequisites

You must implement the following requirements to create and use cluster peering connections with Kubernetes:
- Consul version 1.13.1 or later
- At least two Kubernetes clusters
- The installation must be running on Consul on Kubernetes version 0.47.1 or later

### Helm chart configuration

To establish cluster peering through Kubernetes, deploy clusters with the following Helm values.

  <CodeBlockConfig filename="values.yaml">

  ```yaml
  global:
    image: "hashicorp/consul:1.13.1"
    peering:
      enabled: true
  connectInject:
    enabled: true
  controller:
    enabled: true
  meshGateway:
    enabled: true
    replicas: 1
  ```

  </CodeBlockConfig>

Install Consul on Kubernetes on each Kubernetes cluster by applying `values.yaml` using the Helm CLI. With these values,
the servers in each cluster will be exposed over a Kubernetes Load balancer service. This service can be customized
using [`server.exposeService`](/docs/k8s/helm#v-server-exposeservice). When generating a peering token from one of the
clusters, the address(es) of the load balancer will be used in the peering token, so the peering stream will go through
the load balancer in front of the servers. For customizing the addresses used in the peering token, see
[`global.peering.tokenGeneration`](/docs/k8s/helm#v-global-peering-tokengeneration).

```shell-session
$ export HELM_RELEASE_NAME=cluster-name
```

```shell-session
$ helm install ${HELM_RELEASE_NAME} hashicorp/consul --version "0.47.1" --values values.yaml
```

## Create a peering token

To peer Kubernetes clusters running Consul, you need to create a peering token and share it with the other cluster.

1. In `cluster-01`, create the `PeeringAcceptor` custom resource.

    <CodeBlockConfig filename="acceptor.yml">

    ```yaml
    apiVersion: consul.hashicorp.com/v1alpha1
    kind: PeeringAcceptor
    metadata:
      name: cluster-02 ## The name of the peer you want to connect to
    spec:
      peer:
        secret:
          name: "peering-token"
          key: "data"
          backend: "kubernetes"
    ```

    </CodeBlockConfig>

1. Apply the `PeeringAcceptor` resource to the first cluster.

    ```shell-session
    $ kubectl apply --filename acceptor.yml
    ````

1. Save your peering token so that you can export it to the other cluster.

    ```shell-session
    $ kubectl get secret peering-token --output yaml > peering-token.yml
    ```

## Establish a peering connection between clusters

1. Apply the peering token to the second cluster.

    ```shell-session
    $ kubectl apply --filename peering-token.yml
    ```

1. In `cluster-02`, create the `PeeringDialer` custom resource.

    <CodeBlockConfig filename="dialer.yml">

    ```yaml
    apiVersion: consul.hashicorp.com/v1alpha1
    kind: PeeringDialer
    metadata:
      name: cluster-01 ## The name of the peer you want to connect to
    spec:
      peer:
        secret:
          name: "peering-token"
          key: "data"
          backend: "kubernetes"
    ```

    </CodeBlockConfig>

1. Apply the `PeeringDialer` resource to the second cluster.

    ```shell-session
    $ kubectl apply --filename dialer.yml
    ```

## Export services between clusters

1. For the service in "cluster-02" that you want to export, add the following [annotation](/docs/k8s/annotations-and-labels) to your service's pods.

    <CodeBlockConfig filename="backend-service.yml">

    ```yaml
    ##…
    annotations:
      "consul.hashicorp.com/connect-inject": "true"
    ##…
    ```

    </CodeBlockConfig>

1. In `cluster-02`, create an `ExportedServices` custom resource.

    <CodeBlockConfig filename="exportedsvc.yml">

    ```yaml
    apiVersion: consul.hashicorp.com/v1alpha1
    kind: ExportedServices
    metadata:
      name: default ## The name of the partition containing the service
    spec:
      services:
        - name: backend-service ## The name of the service you want to export
          consumers:
          - peer: cluster-01 ## The name of the peer that receives the service
    ```

    </CodeBlockConfig>

1. Apply the service file and the `ExportedServices` resource for the second cluster.

    ```shell-session
    $ kubectl apply --filename backend-service.yml --filename exportedsvc.yml
    ```

## Authorize services for peers

1. Create service intentions for the second cluster.

    <CodeBlockConfig filename="intention.yml">

    ```yaml
    apiVersion: consul.hashicorp.com/v1alpha1
    kind: ServiceIntentions
    metadata:
      name: backend-deny
    spec:
      destination:
        name: backend-service
      sources:
       - name: "*"
         action: deny
       - name: frontend-service
         action: allow
    ```

    </CodeBlockConfig>

1. Apply the intentions to the second cluster.

    ```shell-session
    $ kubectl apply --filename intention.yml
    ```

1. For the services in `cluster-01` that you want to access the "backend-service," add the following annotations to the service file.

    <CodeBlockConfig filename="frontend-service.yml">

    ```yaml
    ##…
    annotations:
      "consul.hashicorp.com/connect-inject": "true"
    ##…
    ```

    </CodeBlockConfig>

1. Apply the service file to the first cluster.

    ```shell-session
    $ kubectl apply --filename frontend-service.yml
    ```

1. Run the following command in `frontend-service` and check the output to confirm that you peered your clusters successfully.

    ```shell-session
    $ kubectl exec -it $(kubectl get pod -l app=frontend -o name) -- curl localhost:1234
    {
        "name": "backend-service",
        ##…
        "body": "Response from backend",
        "code": 200
    }
    ```

## End a peering connection

To end a peering connection, delete both the `PeeringAcceptor` and `PeeringDialer` resources.

To confirm that you deleted your peering connection, in `cluster-01`, query the `/health` HTTP endpoint. The peered services should no longer appear.

```shell-session
$ curl "localhost:8500/v1/health/connect/backend?peer=cluster-02"
```

## Recreate or reset a peering connection

To recreate or reset the peering connection, you need to generate a new peering token on the cluster where you created the `PeeringAcceptor` (in this example, `cluster-01`).

1. You can do this by creating or updating the annotation `consul.hashicorp.com/peering-version` on the `PeeringAcceptor`. If the annotation already exists, update its value to a version that is higher.

    <CodeBlockConfig filename="acceptor.yml" highlight="6" hideClipboard>

    ```yaml
    apiVersion: consul.hashicorp.com/v1alpha1
    kind: PeeringAcceptor
    metadata:
      name: cluster-02
      annotations:
        consul.hashicorp.com/peering-version: 1 ## The peering version you want to set.
    spec:
      peer:
        secret:
          name: "peering-token"
          key: "data"
          backend: "kubernetes"
    ```

    </CodeBlockConfig>

1. Once you have done this, repeat the steps in the peering process. This includes saving your peering token so that you can export it to the other cluster. This will re-establish peering with the updated token.

~> **Note:** A new peering token is only generated upon manually setting and updating the value of the annotation `consul.hashicorp.com/peering-version`. Creating a new token will cause the previous token to expire.