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Access clusters of a self-managed environment

This section explains how to configure a deployment to connect remotely to self-managed clusters.

Allow the remote connection

Before you start, consider the security model that you would prefer to use for authenticating remote connections between clusters, and follow the corresponding steps.

API key: For deployments based on Elastic Stack version 8.10 or later, you can use an API key to authenticate and authorize cross-cluster operations to a remote cluster. This model offers administrators of both the local and the remote deployment fine-grained access controls.
TLS certificate: This model uses mutual TLS authentication for cross-cluster operations. User authentication is performed on the local cluster and a user’s role names are passed to the remote cluster. A superuser on the local deployment gains total read access to the remote deployment, so it is only suitable for deployments that are in the same security domain.

Specify the deployments trusted to be used as remote clusters

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A deployment can be configured to trust all or specific deployments in any environment:

From the Security menu, select Remote Connections > Add trusted environment and choose Self-managed, then click Next.
Select Certificates as authentication mechanism and click Next.
Upload the public certificate for the Certificate Authority of the self-managed environment (the one used to sign all the cluster certificates). The certificate needs to be in PEM format and should not contain the private key. If you only have the key in p12 format, then you can create the necessary file like this: openssl pkcs12 -in elastic-stack-ca.p12 -out newfile.crt.pem -clcerts -nokeys
Select the clusters to trust. There are two options here depending on the subject name of the certificates presented by the nodes in your self managed cluster:
- Following the Elastic Cloud pattern. In Elastic Cloud, the certificates of all Elasticsearch nodes follow this convention: CN = {node_id}.node.{cluster_id}.cluster.{scope_id}. If you follow the same convention in your self-managed environment, then choose this option and you will be able to select all or specific clusters to trust.
- If your clusters don’t follow the previous convention for the certificates subject name of your nodes, you can still specify the node name of each of the nodes that should be trusted by this deployment. (Keep in mind that following this convention will simplify the management of this cluster since otherwise this configuration will need to be updated every time the topology of your self-managed cluster changes along with the trust restriction file. For this reason, it is recommended migrating your cluster certificates to follow the previous convention).
  
  Trust management will not work properly in clusters without an otherName value specified, as is the case by default in an out-of-the-box Elasticsearch installation. To have the Elasticsearch certutil generate new certificates with the otherName attribute, use the file input with the cn attribute as in the example below.
. Provide a name for the trusted environment. That name will appear in the trust summary of your deployment’s Security page.
Select Create trust to complete the configuration.
Configure the self-managed cluster to trust this deployment, so that both deployments are configured to trust each other:
- Download the Certificate Authority used to sign the certificates of your deployment nodes (it can be found in the Security page of your deployment)
- Trust this CA either using the setting xpack.security.transport.ssl.certificate_authorities in elasticsearch.yml or by adding it to the trust store.
Generate certificates with an otherName attribute using the Elasticsearch certutil. Create a file called instances.yaml with all the details of the nodes in your on-premise cluster like below. The dns and ip settings are optional, but cn is mandatory for use with the trust_restrictions path setting in the next step. Next, run ./bin/elasticsearch-certutil cert --ca elastic-stack-ca.p12 -in instances.yaml to create new certificates for all the nodes at once. You can then copy the resulting files into each node.
```
instances:
  - name: "node1"
    dns: ["node1.mydomain.com"]
    ip: ["192.168.1.1"]
    cn: ["node1.node.1234567abcd.cluster.myscope.account"]
  - name: "node2"
    dns: ["node2.mydomain.com"]
    ip: ["192.168.1.2"]
    cn: ["node2.node.1234567abcd.cluster.myscope.account"]
```
Restrict the trusted clusters to allow only the ones which your self-managed cluster should trust.
- All the clusters in an Elastic Cloud region are signed by the same certificate authority. Therefore, adding this CA would make the self-managed cluster trust all the clusters in that region, including clusters from other organizations. This can be limited using the setting xpack.security.transport.ssl.trust_restrictions.path which points to a file that limits the certificates to trust based on their otherName-attribute.
- For example, the following file would trust:
  - two specific clusters with the cluster IDs aaaabbbbaaaabbbb<1> and xxxxyyyyxxxxyyyy<2> from an organization with organization ID 1053523734
  - <3> any cluster from an organization with organization ID 83988631
  - <4> The nodes from its own cluster (whose certificates follow a different convention: CN = node1.example.com, CN = node2.example.com and CN = node3.example.com)

  trust.subject_name:
  - *.node.aaaabbbbaaaabbbb.cluster.1053523734.account 
  - *.node.xxxxyyyyxxxxyyyy.cluster.1053523734.account 
  - *.node.*.cluster.83988631.account 
  - node*.example.com

Generate new node certificates for an entire cluster using the file input mode of the certutil.

Using the API

You can update a deployment using the appropriate trust settings for the Elasticsearch payload.

In order to trust a cluster whose nodes present certificates with the subject names: "CN = node1.example.com", "CN = node2.example.com" and "CN = node3.example.com" in a self-managed environment, you could update the trust settings with an additional direct trust relationship like this:

{
  "trust":{
    "accounts":[
      {
         "account_id":"ec38dd0aa45f4a69909ca5c81c27138a",
         "trust_all":true
      }
    ],
    "direct": [
      {
        "type" : "generic",
        "name" : "My Self-managed environment",
        "additional_node_names" : ["node1.example.com", "node2.example.com", "node3.example.com",],
        "certificates" : [
            {
                "pem" : "-----BEGIN CERTIFICATE-----\nMIIDTzCCA...H0=\n-----END CERTIFICATE-----"
            }
         ],
         "trust_all":false
       }
    ]
  }
}

API key authentication enables a local cluster to authenticate itself with a remote cluster via a cross-cluster API key. The API key needs to be created by an administrator of the remote cluster. The local cluster is configured to provide this API key on each request to the remote cluster. The remote cluster verifies the API key and grants access, based on the API key’s privileges.

All cross-cluster requests from the local cluster are bound by the API key’s privileges, regardless of local users associated with the requests. For example, if the API key only allows read access to my-index on the remote cluster, even a superuser from the local cluster is limited by this constraint. This mechanism enables the remote cluster’s administrator to have full control over who can access what data with cross-cluster search and/or cross-cluster replication. The remote cluster’s administrator can be confident that no access is possible beyond what is explicitly assigned to the API key.

On the local cluster side, not every local user needs to access every piece of data allowed by the API key. An administrator of the local cluster can further configure additional permission constraints on local users so each user only gets access to the necessary remote data. Note it is only possible to further reduce the permissions allowed by the API key for individual local users. It is impossible to increase the permissions to go beyond what is allowed by the API key.

If you run into any issues, refer to Troubleshooting.

Prerequisites and limitations

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The local and remote deployments must be on version 8.12 or later.
API key authentication can’t be used in combination with traffic filters.
Contrary to the certificate security model, the API key security model does not require that both local and remote clusters trust each other.

Create a cross-cluster API key on the remote deployment

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On the deployment you will use as remote, use the Elasticsearch API or Kibana to create a cross-cluster API key. Configure it with access to the indices you want to use for cross-cluster search or cross-cluster replication.
Copy the encoded key (encoded in the response) to a safe location. You will need it in the next step.

Configure the local deployment

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The API key created previously will be used by the local deployment to authenticate with the corresponding set of permissions to the remote deployment. For that, you need to add the API key to the local deployment’s keystore.

The steps to follow depend on whether the Certificate Authority (CA) of the remote environment’s Elasticsearch HTTPS server, proxy or, load balancing infrastructure is public or private.

The CA is public

Details

Log in to the Elasticsearch Service Console.
Find your deployment on the home page in the Elasticsearch Service card and select Manage to access it directly. Or, select Hosted deployments to go to the deployments page to view all of your deployments.

On the deployments page you can narrow your deployments by name, ID, or choose from several other filters. To customize your view, use a combination of filters, or change the format from a grid to a list.
From the deployment menu, select Security.
Locate Remote connections and select Add an API key.
1. Add a setting:
  - For the Setting name, enter the the alias of your choice. You will use this alias to connect to the remote cluster later. It must be lowercase and only contain letters, numbers, dashes and underscores.
  - For the Secret, paste the encoded cross-cluster API key.
2. Click Add to save the API key to the keystore.
Restart the local deployment to reload the keystore with its new setting. To do that, go to the deployment’s main page (named after your deployment’s name), locate the Actions menu, and select Restart Elasticsearch.

If the local deployment runs on version 8.13 or greater, you no longer need to perform this step because the keystore is reloaded automatically with the new API keys.

If you later need to update the remote connection with different permissions, you can replace the API key as detailed in Update the access level of a remote cluster connection relying on a cross-cluster API key.

The CA is private

Details

Log in to the Elasticsearch Service Console.
Find your deployment on the home page in the Elasticsearch Service card and select Manage to access it directly. Or, select Hosted deployments to go to the deployments page to view all of your deployments.

On the deployments page you can narrow your deployments by name, ID, or choose from several other filters. To customize your view, use a combination of filters, or change the format from a grid to a list.
Access the Security page of the deployment.
Select Remote Connections > Add trusted environment and choose Self-managed. Then click Next.
Select API keys as authentication mechanism and click Next.
Add a the API key:
1. Fill both fields.
  - For the Setting name, enter the the alias of your choice. You will use this alias to connect to the remote cluster later. It must be lowercase and only contain letters, numbers, dashes and underscores.
  - For the Secret, paste the encoded cross-cluster API key.
2. Click Add to save the API key to the keystore.
3. Repeat these steps for each API key you want to add. For example, if you want to use several clusters of the remote environment for CCR or CCS.
Add the CA certificate of the remote self-managed environment.
Provide a name for the trusted environment. That name will appear in the trust summary of your deployment’s Security page.
Select Create trust to complete the configuration.
Restart the local deployment to reload the keystore with its new setting. To do that, go to the deployment’s main page (named after your deployment’s name), locate the Actions menu, and select Restart Elasticsearch.

If the local deployment runs on version 8.13 or greater, you no longer need to perform this step because the keystore is reloaded automatically with the new API keys.

You can now connect remotely to the trusted clusters.

Connect to the remote cluster

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On the local cluster, add the remote cluster using Kibana or the Elasticsearch API.

Using Kibana

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Open the Kibana main menu, and select Stack Management > Data > Remote Clusters > Add a remote cluster.
Enable Manually enter proxy address and server name.
Fill in the following fields:
- Name: This cluster alias is a unique identifier that represents the connection to the remote cluster and is used to distinguish between local and remote indices.
- Proxy address: This value can be found on the Security page of the Elasticsearch Service deployment you want to use as a remote.
  
  If you’re using API keys as security model, change the port into 9443.
- Server name: This value can be found on the Security page of the Elasticsearch Service deployment you want to use as a remote.
  
  If you’re having issues establishing the connection and the remote cluster is part of an Elastic Cloud Enterprise environment with a private certificate, make sure that the proxy address and server name match with the the certificate information. For more information, refer to Administering endpoints in Elastic Cloud Enterprise.
Click Next.
Click Add remote cluster (you have already established trust in a previous step).

Using the Elasticsearch API

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To configure a deployment as a remote cluster, use the cluster update settings API. Configure the following fields:

mode: proxy
proxy_address: This value can be found on the Security page of the Elasticsearch Service deployment you want to use as a remote. Also, using the API, this value can be obtained from the Elasticsearch resource info, concatenating the field metadata.endpoint and port 9400 using a semicolon.

If you’re using API keys as security model, change the port into 9443.

server_name: This value can be found on the Security page of the Elasticsearch Service deployment you want to use as a remote. Also, using the API, this can be obtained from the Elasticsearch resource info field metadata.endpoint.

This is an example of the API call to _cluster/settings:

PUT /_cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "alias-for-my-remote-cluster": {
          "mode":"proxy",
          "proxy_address": "a542184a7a7d45b88b83f95392f450ab.192.168.44.10.ip.es.io:9400",
          "server_name": "a542184a7a7d45b88b83f95392f450ab.192.168.44.10.ip.es.io"
        }
      }
    }
  }
}

Stack Version above 6.7.0 and below 7.6.0

This section only applies if you’re using TLS certificates as cross-cluster security model.

When the cluster to be configured as a remote is above 6.7.0 and below 7.6.0, the remote cluster must be configured using the sniff mode with the proxy field. For each remote cluster you need to pass the following fields:

Proxy: This value can be found on the Security page of the deployment you want to use as a remote under the name Proxy Address. Also, using the API, this can be obtained from the elasticsearch resource info, concatenating the fields metadata.endpoint and metadata.ports.transport_passthrough using a semicolon.
Seeds: This field is an array that must contain only one value, which is the server name that can be found on the Security page of the {s} deployment you want to use as a remote concatenated with :1. Also, using the API, this can be obtained from the Elasticsearch resource info, concatenating the fields metadata.endpoint and 1 with a semicolon.
Mode: sniff (or empty, since sniff is the default value)

This is an example of the API call to _cluster/settings:

{
  "persistent": {
    "cluster": {
      "remote": {
        "my-remote-cluster-1": {
          "seeds": [
            "a542184a7a7d45b88b83f95392f450ab.192.168.44.10.ip.es.io:1"
          ],
          "proxy": "a542184a7a7d45b88b83f95392f450ab.192.168.44.10.ip.es.io:9400"
        }
      }
    }
  }
}

Using the Elasticsearch Service RESTful API

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This section only applies if you’re using TLS certificates as cross-cluster security model and when both clusters belong to the same organization (for other scenarios,the Elasticsearch API should be used instead):

curl -H 'Content-Type: application/json' -X PUT -H "Authorization: ApiKey $EC_API_KEY" https://api.elastic-cloud.com/api/v1/deployments/$DEPLOYMENT_ID/elasticsearch/$REF_ID/remote-clusters -d '
{
  "resources" : [
    {
      "deployment_id": "$DEPLOYMENT_ID_REMOTE",
      "elasticsearch_ref_id": "$REF_ID_REMOTE",
      "alias": "alias-your-remote",
      "skip_unavailable" : true
    }
  ]
}'

DEPLOYMENT_ID_REMOTE: The ID of your remote deployment, as shown in the Cloud UI or obtained through the API.
REF_ID_REMOTE: The unique ID of the Elasticsearch resources inside your remote deployment (you can obtain these values through the API).

Note the following when using the Elasticsearch Service RESTful API:

A cluster alias must contain only letters, numbers, dashes (-), or underscores (_).
To learn about skipping disconnected clusters, refer to the Elasticsearch documentation.
When remote clusters are already configured for a deployment, the PUT request replaces the existing configuration with the new configuration passed. Passing an empty array of resources will remove all remote clusters.

The following API request retrieves the remote clusters configuration:

curl -X GET -H "Authorization: ApiKey $EC_API_KEY" https://api.elastic-cloud.com/api/v1/deployments/$DEPLOYMENT_ID/elasticsearch/$REF_ID/remote-clusters

The response will include just the remote clusters from the same organization in Elasticsearch Service. In order to obtain the whole list of remote clusters, use Kibana or the Elasticsearch API Elasticsearch API directly.

Configure roles and users

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To use a remote cluster for cross-cluster replication or cross-cluster search, you need to create user roles with remote indices privileges on the local cluster. Refer to Configure roles and users.

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