With ES|QL, you can execute a single query across multiple clusters.

Prerequisitesedit

Security modeledit

Elasticsearch supports two security models for cross-cluster search (CCS):

TLS certificate authenticationedit

TLS certificate authentication secures remote clusters with mutual TLS. This could be the preferred model when a single administrator has full control over both clusters. We generally recommend that roles and their privileges be identical in both clusters.

Refer to TLS certificate authentication for prerequisites and detailed setup instructions.

API key authenticationedit

The following information pertains to using ES|QL across clusters with the API key based security model. You’ll need to follow the steps on that page for the full setup instructions. This page only contains additional information specific to ES|QL.

API key based cross-cluster search (CCS) enables more granular control over allowed actions between clusters. This may be the preferred model when you have different administrators for different clusters and want more control over who can access what data. In this model, cluster administrators must explicitly define the access given to clusters and users.

You will need to:

Using ES|QL with the API key based security model requires some additional permissions that may not be needed when using the traditional query DSL based search. The following example API call creates a role that can query remote indices using ES|QL when using the API key based security model.

POST /_security/role/remote1
{
  "cluster": ["cross_cluster_search"], 
  "indices": [
    {
      "names" : [""], 
      "privileges": ["read"]
    }
  ],
  "remote_indices": [ 
    {
      "names": [ "logs-*" ],
      "privileges": [ "read","read_cross_cluster" ], 
      "clusters" : ["my_remote_cluster"] 
    }
  ]
}

You will then need a user or API key with the permissions you created above. The following example API call creates a user with the remote1 role.

POST /_security/user/remote_user
{
  "password" : "<PASSWORD>",
  "roles" : [ "remote1" ]
}

Remember that all cross-cluster requests from the local cluster are bound by the cross cluster API key’s privileges, which are controlled by the remote cluster’s administrator.

Remote cluster setupedit

Once the security model is configured, you can add remote clusters.

The following cluster update settings API request adds three remote clusters: cluster_one, cluster_two, and cluster_three.

response = client.cluster.put_settings(
  body: {
    persistent: {
      cluster: {
        remote: {
          cluster_one: {
            seeds: [
              '35.238.149.1:9300'
            ],
            skip_unavailable: true
          },
          cluster_two: {
            seeds: [
              '35.238.149.2:9300'
            ],
            skip_unavailable: false
          },
          cluster_three: {
            seeds: [
              '35.238.149.3:9300'
            ]
          }
        }
      }
    }
  }
)
puts response

PUT _cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "cluster_one": {
          "seeds": [
            "35.238.149.1:9300"
          ],
          "skip_unavailable": true
        },
        "cluster_two": {
          "seeds": [
            "35.238.149.2:9300"
          ],
          "skip_unavailable": false
        },
        "cluster_three": {  
          "seeds": [
            "35.238.149.3:9300"
          ]
        }
      }
    }
  }
}

Query across multiple clustersedit

In the FROM command, specify data streams and indices on remote clusters using the format <remote_cluster_name>:<target>. For instance, the following ES|QL request queries the my-index-000001 index on a single remote cluster named cluster_one:

FROM cluster_one:my-index-000001
| LIMIT 10

Similarly, this ES|QL request queries the my-index-000001 index from three clusters:

FROM my-index-000001,cluster_one:my-index-000001,cluster_two:my-index-000001
| LIMIT 10

Likewise, this ES|QL request queries the my-index-000001 index from all remote clusters (cluster_one, cluster_two, and cluster_three):

FROM *:my-index-000001
| LIMIT 10

Enrich across clustersedit

Enrich in ES|QL across clusters operates similarly to local enrich. If the enrich policy and its enrich indices are consistent across all clusters, simply write the enrich command as you would without remote clusters. In this default mode, ES|QL can execute the enrich command on either the local cluster or the remote clusters, aiming to minimize computation or inter-cluster data transfer. Ensuring that the policy exists with consistent data on both the local cluster and the remote clusters is critical for ES|QL to produce a consistent query result.

In the following example, the enrich with hosts policy can be executed on either the local cluster or the remote cluster cluster_one.

FROM my-index-000001,cluster_one:my-index-000001
| ENRICH hosts ON ip
| LIMIT 10

Enrich with an ES|QL query against remote clusters only can also happen on the local cluster. This means the below query requires the hosts enrich policy to exist on the local cluster as well.

FROM cluster_one:my-index-000001,cluster_two:my-index-000001
| LIMIT 10
| ENRICH hosts ON ip

Enrich with coordinator modeedit

ES|QL provides the enrich _coordinator mode to force ES|QL to execute the enrich command on the local cluster. This mode should be used when the enrich policy is not available on the remote clusters or maintaining consistency of enrich indices across clusters is challenging.

FROM my-index-000001,cluster_one:my-index-000001
| ENRICH _coordinator:hosts ON ip
| SORT host_name
| LIMIT 10

Enrich with remote modeedit

ES|QL also provides the enrich _remote mode to force ES|QL to execute the enrich command independently on each remote cluster where the target indices reside. This mode is useful for managing different enrich data on each cluster, such as detailed information of hosts for each region where the target (main) indices contain log events from these hosts.

In the below example, the hosts enrich policy is required to exist on all remote clusters: the querying cluster (as local indices are included), the remote cluster cluster_one, and cluster_two.

FROM my-index-000001,cluster_one:my-index-000001,cluster_two:my-index-000001
| ENRICH _remote:hosts ON ip
| SORT host_name
| LIMIT 10

A _remote enrich cannot be executed after a stats command. The following example would result in an error:

FROM my-index-000001,cluster_one:my-index-000001,cluster_two:my-index-000001
| STATS COUNT(*) BY ip
| ENRICH _remote:hosts ON ip
| SORT host_name
| LIMIT 10

Multiple enrich commandsedit

You can include multiple enrich commands in the same query with different modes. ES|QL will attempt to execute them accordingly. For example, this query performs two enriches, first with the hosts policy on any cluster and then with the vendors policy on the local cluster.

FROM my-index-000001,cluster_one:my-index-000001,cluster_two:my-index-000001
| ENRICH hosts ON ip
| ENRICH _coordinator:vendors ON os
| LIMIT 10

A _remote enrich command can’t be executed after a _coordinator enrich command. The following example would result in an error.

FROM my-index-000001,cluster_one:my-index-000001,cluster_two:my-index-000001
| ENRICH _coordinator:hosts ON ip
| ENRICH _remote:vendors ON os
| LIMIT 10

Excluding clusters or indices from ES|QL queryedit

To exclude an entire cluster, prefix the cluster alias with a minus sign in the FROM command, for example: -my_cluster:*:

FROM my-index-000001,cluster*:my-index-000001,-cluster_three:*
| LIMIT 10

To exclude a specific remote index, prefix the index with a minus sign in the FROM command, such as my_cluster:-my_index:

FROM my-index-000001,cluster*:my-index-*,cluster_three:-my-index-000001
| LIMIT 10

Optional remote clustersedit

Cross-cluster search for ES|QL currently does not respect the skip_unavailable setting. As a result, if a remote cluster specified in the request is unavailable or failed, cross-cluster search for ES|QL queries will fail regardless of the setting.

We are actively working to align the behavior of cross-cluster search for ES|QL with other cross-cluster search APIs. This includes providing detailed execution information for each cluster in the response, such as execution time, selected target indices, and shards.

Query across clusters during an upgradeedit

You can still search a remote cluster while performing a rolling upgrade on the local cluster. However, the local coordinating node’s "upgrade from" and "upgrade to" version must be compatible with the remote cluster’s gateway node.

For more information about upgrades, see Upgrading Elasticsearch.