--- title: Connect self-managed clusters to Elastic Cloud on Kubernetes description: These steps describe how to configure a remote cluster connection from a self-managed Elasticsearch cluster, to an Elastic Cloud on Kubernetes (ECK) managed... url: https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/self-remote-cluster-eck products: - Elastic Cloud on Kubernetes applies_to: - Elastic Cloud on Kubernetes: Generally available --- # Connect self-managed clusters to Elastic Cloud on Kubernetes These steps describe how to configure a remote cluster connection from a self-managed Elasticsearch cluster, to an Elastic Cloud on Kubernetes (ECK) managed cluster. After the connection is established, you’ll be able to [run CCS queries from Elasticsearch](https://www.elastic.co/elastic/docs-builder/docs/3016/explore-analyze/cross-cluster-search) or [set up CCR](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/tools/cross-cluster-replication/set-up-cross-cluster-replication). In the case of remote clusters, the Elasticsearch cluster or deployment initiating the connection and requests is often referred to as the **local cluster**, while the Elasticsearch cluster or deployment receiving the requests is referred to as the **remote cluster**. For other remote cluster scenarios with ECK, refer to [Remote clusters on ECK](/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/eck-remote-clusters-landing#eck-rcs-setup). ## Allow the remote connection Before you start, consider the [security model](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/security-models) that you would prefer to use for authenticating remote connections between clusters, and follow the corresponding steps. For deployments based on Elastic Stack 8.14 or later, you can use an API key to authenticate and authorize cross-cluster operations to a remote cluster. This model uses a dedicated service endpoint, on port `9443` by default, and gives administrators fine-grained control over remote access. The API key is created on the remote cluster and defines the permissions available to all cross-cluster requests, while local user roles can further restrict, but not extend, those permissions. Starting with Elastic Stack 9.3, the API key security model also supports [strong identity verification](/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/security-models#remote-cluster-strong-verification), adding an extra layer of security. With this feature, the API key can be restricted to only be usable by requests that present an allowed certificate identity, which the remote cluster validates during authentication. This model uses mutual TLS authentication over the Elasticsearch transport interface for cross-cluster operations. User authentication is performed on the local cluster and a user's role names are passed to the remote cluster for authorization. Because a superuser on the local cluster automatically gains full read access to the remote cluster, this model is only suitable for clusters within the same security domain. Follow these steps to configure the [API key security model](/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/security-models#api-key) for remote clusters. If you run into any issues, refer to [Troubleshooting](https://www.elastic.co/elastic/docs-builder/docs/3016/troubleshoot/elasticsearch/remote-clusters). #### Prerequisites and limitations - The local and remote deployments must be on Elastic Stack 8.14 or later. - Unlike the certificate-based security model, the API key model does not require mutual trust between clusters; only the local cluster is required to trust the remote cluster's certificate. #### Enable the remote cluster server interface on the remote ECK cluster By default, the remote cluster server interface is not enabled on ECK-managed clusters. To use the API key–based security model for cross-cluster connections, you must first enable it on the remote Elasticsearch cluster by setting `spec.remoteClusterServer.enabled: true`: ```yaml apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: namespace: spec: version: 9.3.2 remoteClusterServer: enabled: true nodeSets: - name: default count: 3 ... ... ``` Enabling the remote cluster server triggers a restart of the Elasticsearch cluster. #### Configure external access to the remote cluster server interface When the remote cluster server is enabled, ECK automatically creates a Kubernetes service named `-es-remote-cluster` that exposes the server internally on port `9443`. To allow clusters running outside your Kubernetes environment to connect to this Elasticsearch cluster, you must expose this service externally. The way to expose this service depends on your ECK version. You can customize how the remote cluster service is exposed by overriding its service specification directly under `spec.remoteClusterServer.service` in the Elasticsearch resource. By default, this service listens on port 9443. ```yaml apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: namespace: spec: version: 9.2.1 remoteClusterServer: enabled: true service: spec: type: LoadBalancer nodeSets: - name: default count: 3 ... ... ``` 1. On cloud providers that support external load balancers, setting the type to `LoadBalancer` provisions a load balancer for your service. Alternatively, expose the service `-es-remote-cluster` through one of the Kubernetes Ingress controllers that support TCP services. You can't customize the service that ECK generates for the remote cluster interface, but you can create your own `LoadBalancer` service, `Ingress` object, or use another method available in your environment.For example, for a cluster named `quickstart`, the following command creates a separate `LoadBalancer` service named `quickstart-es-remote-cluster-lb`, pointing to the ECK-managed service `quickstart-es-remote-cluster`: ```sh kubectl expose service quickstart-es-remote-cluster \ --name=quickstart-es-remote-cluster-lb \ --type=LoadBalancer \ --port=9443 --target-port=9443 ``` 1. On cloud providers that support external load balancers, setting the type to `LoadBalancer` provisions a load balancer for your service. Alternatively, expose the service `-es-remote-cluster` through one of the Kubernetes Ingress controllers that support TCP services. If you change the service’s `port` to expose a different port externally, set `targetPort` explicitly to `9443`, which is the default remote cluster server listening port. Otherwise, Kubernetes uses the same value for both fields, resulting in failed connections. #### Retrieve the ECK-managed CA certificate of the remote cluster server The certificate authority (CA) used by ECK to issue certificates for the remote cluster server interface is stored in the `ca.crt` key of the secret named `-es-transport-certs-public`. If the external connections reach the Elasticsearch Pods on port `9443` without any intermediate TLS termination, you need to retrieve this CA because it is required in the local cluster configuration to establish trust. If TLS is terminated by any intermediate component and the certificate presented is not the ECK-managed one, use the CA associated with that component, or omit the CA entirely if it uses a publicly trusted certificate. To save the transport CA certificate of a cluster named `quickstart` into a local file, run the following command: ```sh kubectl get secret quickstart-es-transport-certs-public \ -o go-template='{{index .data "ca.crt" | base64decode}}' > eck_transport_ca.crt ``` ECK-managed CA certificates are automatically rotated after one year by default, but you can [configure](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/deploy/cloud-on-k8s/configure-eck) a different validity period. When the CA certificate is rotated, ensure that this CA is updated in all environments where it's used to preserve trust. #### Create a cross-cluster API key on the remote cluster 1. On the remote cluster, use the [Elasticsearch API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-security-create-cross-cluster-api-key) or [Kibana](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/api-keys/elasticsearch-api-keys) to create a cross-cluster API key. Configure it to include access to the indices you want to use for cross-cluster search or cross-cluster replication. 2. Copy the encoded key (`encoded` in the response) to a safe location. It is required for the local cluster configuration. #### Configure the local deployment The API key created previously is needed by the local cluster to authenticate with the corresponding set of permissions to the remote cluster. To enable this, add the API key to the local cluster's keystore. 1. On every node of the local cluster: 1. Copy the `ca.crt` file generated on the remote cluster earlier into the `config` directory, renaming the file `remote-cluster-ca.crt`. 2. Add following configuration to [`elasticsearch.yml`](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/stack-settings): ```yaml xpack.security.remote_cluster_client.ssl.enabled: true xpack.security.remote_cluster_client.ssl.certificate_authorities: [ "remote-cluster-ca.crt" ] ``` If the remote cluster uses a publicly trusted certificate, don't include the `certificate_authorities` setting. This example assumes the remote is using certificates signed by a private certificate authority (CA), which requires the CA to be added. 3. Add the cross-cluster API key, created on the remote cluster earlier, to the keystore: ```sh ./bin/elasticsearch-keystore add cluster.remote..credentials ``` Replace `ALIAS` with the same name that you intend to use to create the remote cluster entry later. When prompted, enter the encoded cross-cluster API key created on the remote cluster earlier. 2. Restart the local cluster to load changes to the keystore and settings. If you are configuring only the cross-cluster API key, you can use the [Nodes reload secure settings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-nodes-reload-secure-settings) instead of restarting the cluster. Configuring the `remote_cluster_client` settings in `elasticsearch.yml` still requires a restart. Follow these steps to configure the [TLS certificate security model](/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/security-models#tls-certificate-authentication) for remote clusters. If you run into any issues, refer to [Troubleshooting](https://www.elastic.co/elastic/docs-builder/docs/3016/troubleshoot/elasticsearch/remote-clusters). #### Make sure both clusters trust each other's certificate authority When using TLS certificate–based authentication, the first step is to establish mutual trust between the clusters at the transport layer. This requires exchanging and trusting each cluster's transport certificate authority (CA): - The transport CA of the remote cluster must be added as a trusted CA in the local cluster. - The local cluster’s transport CA must be added as a trusted CA in the remote cluster. In this example: - The remote cluster resides inside Kubernetes and is managed by ECK - The local cluster is a self-managed cluster running outside of Kubernetes. To allow mutual TLS authentication between the clusters: 1. Extract and save the transport CAs of both clusters: 1. For the ECK-managed cluster: ECK stores the CA used to issue certificates for the Elasticsearch transport layer in a secret named `-es-transport-certs-public`. For example, to save the transport CA certificate of a cluster named `quickstart` into a local file, run the following command: ```sh kubectl get secret quickstart-es-transport-certs-public \ -o go-template='{{index .data "ca.crt" | base64decode}}' > quickstart_transport_ca.crt ``` Beware of copying the source secret as-is into a different namespace. Refer to [Copying secrets with Owner References](/elastic/docs-builder/docs/3016/troubleshoot/deployments/cloud-on-k8s/common-problems#k8s-common-problems-owner-refs) for more information. CA certificates are automatically rotated after one year by default. You can [configure](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/deploy/cloud-on-k8s/configure-eck) this period. Make sure to keep the copy of the certificates secret up-to-date. 2. For the self-managed cluster, retrieve the transport CA from any of the nodes of the cluster. You can save it as `self-managed_ca.crt`. 2. Configure the self-managed cluster to trust the transport CA of the ECK-managed cluster as follows: Add the ECK-managed cluster’s CA to the list of CAs in [`xpack.security.transport.ssl.certificate_authorities`](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/3016/reference/elasticsearch/configuration-reference/security-settings#_pem_encoded_files_3). 3. Configure the ECK-managed cluster to trust the transport CA of the self-managed cluster: 1. Create a ConfigMap with the CA certificate you extracted previously: ```sh kubectl create configmap remote-certs --from-file=ca.crt= ``` 2. Configure the Elasticsearch resource manifest to trust the config map's CA through the `spec.transport.tls.certificate_authorities` setting: ```yaml apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: spec: version: 9.3.2 transport: tls: certificateAuthorities: configMapName: remote-certs nodeSets: - count: 3 name: default ``` #### Configure external access to the transport interface of the remote cluster Expose the transport service (defaults to port `9300`) of your ECK cluster to allow external Elasticsearch clusters to connect: ```yaml apiVersion: elasticsearch.k8s.elastic.co/v1 kind: Elasticsearch metadata: name: spec: transport: service: spec: type: LoadBalancer ``` 1. On cloud providers which support external load balancers, setting the `type` field to `LoadBalancer` provisions a load balancer for your service. Alternatively, expose the service `-es-transport` through one of the Kubernetes Ingress controllers that support TCP services. If you change the service’s `port` to expose a different port externally, set `targetPort` explicitly to `9300`, which is the default transport service listening port. Otherwise, Kubernetes uses the same value for both fields, resulting in failed connections. ## Connect to the remote cluster On the local cluster, use Kibana or the Elasticsearch API to add the remote ECK cluster with the following connection settings: - **Remote address**: Use the FQDN or IP address of the LoadBalancer service or alternative resource that you created to expose the remote cluster. - For API key-based authentication, use the server interface address and port. - For TLS certificate-based authentication, use the transport interface address and port. If you haven't changed the external listening port of the kubernetes service, the port should be `9443` for API key-based authentication, or `9300` for TLS certificate-based authentication. - **TLS server name**: You can try leaving this field empty first. If the connection fails, and your environment is presenting the ECK-managed certificates during the TLS handshake, use `-es-remote-cluster..svc` as the server name. For example, for a cluster named `quickstart` in the `default` namespace, use `quickstart-es-remote-cluster.default.svc`. This guide uses the `proxy` connection mode, connecting to the remote cluster through the Kubernetes service abstraction. Refer to [connection modes](https://www.elastic.co/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/connection-modes) documentation for details on each mode and their connectivity requirements. ### Using Kibana To add a remote cluster in Kibana: 1. Go to the **Remote Clusters** management page in the navigation menu or use the [global search field](https://www.elastic.co/elastic/docs-builder/docs/3016/explore-analyze/find-and-organize/find-apps-and-objects). 2. Select **Add a remote cluster**. 3. In **Select connection type**, choose the authentication mechanism you prepared earlier (**API keys** or **Certificates**), and click **Next**. 4. Set the **Remote cluster name**: This *cluster alias* is a unique identifier that represents the connection to the remote cluster and is used to distinguish local and remote indices. When using API key authentication, this alias must match the **Remote cluster name** you configured when [adding the API key](#configure-local-cluster). 5. In **Connection mode**, select **Manually enter proxy address and server name** to enable the proxy mode and fill in the following fields: - **Proxy address**: Enter the endpoint of the remote cluster, including the hostname, FQDN, or IP address, and the port: Make sure you use the correct port for your authentication method: - **API keys**: Use the port configured in the remote cluster interface of the remote cluster (defaults to `9443`). - **TLS certificates**: Use the Elasticsearch transport port (defaults to `9300`). Starting with Kibana 9.2, this field also supports IPv6 addresses. When using an IPv6 address, enclose it in square brackets followed by the port number. For example: `[2001:db8::1]:9443`. - **Server name (optional)**: Specify a value if the TLS certificate presented by the remote cluster is signed for a different name than the remote address. 6. Click **Next**. 7. In **Confirm setup**, click **Add remote cluster** (you have already established trust in a previous step). ### Using the Elasticsearch API To add a remote cluster, use the [cluster update settings API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-cluster-put-settings). Configure the following fields: - **Remote cluster alias**: When using API key authentication, the cluster alias must match the one you configured when [adding the API key](#configure-local-cluster). - **mode**: `proxy` - **proxy_address**: Enter the endpoint of the remote cluster, including the hostname, FQDN, or IP address, and the port. Both IPv4 and IPv6 addresses are supported. Make sure you use the correct port for your authentication method: - **API keys**: Use the port configured in the remote cluster interface of the remote cluster (defaults to `9443`). - **TLS Certificates**: Use the Elasticsearch transport port (defaults to `9300`). When using an IPv6 address, enclose it in square brackets followed by the port number. For example: `[2001:db8::1]:9443`. - **server_name**: Specify a value if the certificate presented by the remote cluster is signed for a different name than the proxy_address. This is an example of the API call to add or update a remote cluster: ```json PUT /_cluster/settings { "persistent": { "cluster": { "remote": { "alias-for-my-remote-cluster": { "mode":"proxy", "proxy_address": ":9443", "server_name": "" } } } } } ``` For a full list of available client connection settings in proxy mode, refer to the [remote cluster settings reference](https://docs-v3-preview.elastic.dev/elastic/docs-builder/docs/3016/reference/elasticsearch/configuration-reference/remote-clusters#remote-cluster-proxy-settings). ## Configure roles and users If you're using the API key–based security model for cross-cluster replication or cross-cluster search, you can define user roles with [remote indices privileges](/elastic/docs-builder/docs/3016/deploy-manage/users-roles/cluster-or-deployment-auth/role-structure#roles-remote-indices-priv) on the local cluster to further restrict the permissions granted by the API key. For more details, refer to [Configure roles and users](/elastic/docs-builder/docs/3016/deploy-manage/remote-clusters/remote-clusters-api-key#remote-clusters-privileges-api-key).