Note: If you are configuring only the cross-cluster API key, you can call the Nodes reload secure settings API, instead of restarting the cluster. Configuring the remote_cluster_client settings in elasticsearch.yml still requires a restart.

Use the cluster update settings API to dynamically configure remote settings on every node in the cluster. The following request adds three remote clusters: cluster_one, cluster_two, and cluster_three.

The seeds parameter specifies the hostname and remote cluster port (default 9443) of a seed node in the remote cluster.

The mode parameter determines the configured connection mode, which defaults to sniff. Because cluster_one doesn’t specify a mode, it uses the default. Both cluster_two and cluster_three explicitly use different modes.

PUT _cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "cluster_one": {
          "seeds": [
            "127.0.0.1:9443"
          ]
        },
        "cluster_two": {
          "mode": "sniff",
          "seeds": [
            "127.0.0.1:9444"
          ],
          "transport.compress": true,
          "skip_unavailable": true
        },
        "cluster_three": {
          "mode": "proxy",
          "proxy_address": "127.0.0.1:9445"
        }
      }
    }
  }
}

You can dynamically update settings for a remote cluster after the initial configuration. The following request updates the compression settings for cluster_two, and the compression and ping schedule settings for cluster_three.

response = client.cluster.put_settings(
  body: {
    persistent: {
      cluster: {
        remote: {
          cluster_two: {
            'transport.compress' => false
          },
          cluster_three: {
            'transport.compress' => true,
            'transport.ping_schedule' => '60s'
          }
        }
      }
    }
  }
)
puts response

PUT _cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "cluster_two": {
          "transport.compress": false
        },
        "cluster_three": {
          "transport.compress": true,
          "transport.ping_schedule": "60s"
        }
      }
    }
  }
}

You can delete a remote cluster from the cluster settings by passing null values for each remote cluster setting. The following request removes cluster_two from the cluster settings, leaving cluster_one and cluster_three intact:

response = client.cluster.put_settings(
  body: {
    persistent: {
      cluster: {
        remote: {
          cluster_two: {
            mode: nil,
            seeds: nil,
            skip_unavailable: nil,
            'transport.compress' => nil
          }
        }
      }
    }
  }
)
puts response

PUT _cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "cluster_two": {
          "mode": null,
          "seeds": null,
          "skip_unavailable": null,
          "transport.compress": null
        }
      }
    }
  }
}

If you specify settings in elasticsearch.yml, only the nodes with those settings can connect to the remote cluster and serve remote cluster requests.

In the following example, cluster_one, cluster_two, and cluster_three are arbitrary cluster aliases representing the connection to each cluster. These names are subsequently used to distinguish between local and remote indices.

cluster:
    remote:
        cluster_one:
            seeds: 127.0.0.1:9443
        cluster_two:
            mode: sniff
            seeds: 127.0.0.1:9444
            transport.compress: true      
            skip_unavailable: true        
        cluster_three:
            mode: proxy
            proxy_address: 127.0.0.1:9445 

Assuming the remote cluster is connected under the name of my_remote_cluster, the following request creates a role called remote-replication on the local cluster that allows replicating the remote leader-index index:

POST /_security/role/remote-replication
{
  "cluster": [
    "manage_ccr"
  ],
  "remote_indices": [
    {
      "clusters": [ "my_remote_cluster" ],
      "names": [
        "leader-index"
      ],
      "privileges": [
        "cross_cluster_replication"
      ]
    }
  ]
}

After creating the local remote-replication role, use the Create or update users API to create a user on the local cluster cluster and assign the remote-replication role. For example, the following request assigns the remote-replication role to a user named cross-cluster-user:

POST /_security/user/cross-cluster-user
{
  "password" : "l0ng-r4nd0m-p@ssw0rd",
  "roles" : [ "remote-replication" ]
}

Note that you only need to create this user on the local cluster.

Assuming the remote cluster is connected under the name of my_remote_cluster, the following request creates a remote-search role on the local cluster that allows searching the remote target-index index:

POST /_security/role/remote-search
{
  "remote_indices": [
    {
      "clusters": [ "my_remote_cluster" ],
      "names": [
        "target-index"
      ],
      "privileges": [
        "read",
        "read_cross_cluster",
        "view_index_metadata"
      ]
    }
  ]
}

After creating the remote-search role, use the Create or update users API to create a user on the local cluster and assign the remote-search role. For example, the following request assigns the remote-search role to a user named cross-search-user:

POST /_security/user/cross-search-user
{
  "password" : "l0ng-r4nd0m-p@ssw0rd",
  "roles" : [ "remote-search" ]
}

Note that you only need to create this user on the local cluster.