anchor.diff:    connected to if `search.remote.node.attr` is set to `gateway`.
   
   `search.remote.connect`::
  - By default, any node in the cluster can act as a cross-cluster client and connect to remote clusters.
  - The `search.remote.connect` setting can be set to `false` (defaults to `true`) to prevent certain nodes from
  - connecting to remote clusters. Cross-cluster search requests must be sent to a node that is allowed to act as a
  - cross-cluster client.
  +
  +  By default, any node in the cluster can act as a cross-cluster client and
  +  connect to remote clusters. The `search.remote.connect` setting can be set
  +  to `false` (defaults to `true`) to prevent certain nodes from connecting to
  +  remote clusters. Cross-cluster search requests must be sent to a node that
  +  is allowed to act as a cross-cluster client.
   
   
  
positive.code: [[modules-cross-cluster-search]]
  == Cross cluster search
  
  experimental[]
  
  The _cross cluster search_ feature allows any node to act as a federated client across
  multiple clusters. In contrast to the _tribe_ feature, a  _cross cluster search_ node won't
  join the remote cluster, instead it connects to a remote cluster in a light fashion in order to execute
  federated search requests.
  
  The _cross cluster search_ feature works by configuring a remote cluster in the cluster state and connects only to a
  limited number of nodes in the remote cluster. Each remote cluster is referenced by a name and a list of seed nodes.
  Those seed nodes are used to discover other nodes eligible as so-called _gateway nodes_. Each node in a cluster that
  has remote clusters configured connects to one or more _gateway nodes_ and uses them to federate search requests to
  the remote cluster.
  
  Remote clusters can either be configured as part of the `elasticsearch.yml` file or be dynamically updated via
  the <<cluster-update-settings,cluster settings API>>. If a remote cluster is configured via `elasticsearch.yml` only
  the nodes with the configuration set will be connecting to the remote cluster in which case federated search requests
  will have to be sent specifically to those nodes. Remote clusters set via the
  <<cluster-update-settings,cluster settings API>> will be available on every node in the cluster.
  
  [WARNING]
  This feature was added in Elasticsearch `v5.3` and requires gateway eligible nodes to be on `v5.3` onwards.
  
negative.code: --------------------------------
  <1> `cluster_one` and `cluster_two` are arbitrary cluster aliases representing the connection to each cluster.
  These names are subsequently used to distinguish between local and remote indices.
  
  The equivalent example using the <<cluster-update-settings,cluster settings API>>
  to add remote clusters to all nodes in the cluster would look like the
  following:
  
  [source,js]
  --------------------------------
  PUT _cluster/settings
  {
    "persistent": {
      "search": {
        "remote": {
          "cluster_one": {
            "seeds": [
              "127.0.0.1:9300"
            ]
          },
          "cluster_two": {
            "seeds": [
              "127.0.0.1:9301"
            ]
          }
        }
      }
    }
  }
  --------------------------------
  // CONSOLE
  
  A remote cluster can be deleted from the cluster settings by setting its seeds to `null`:
  
  [source,js]
  --------------------------------
  PUT _cluster/settings
  {
    "persistent": {
      "search": {
        "remote": {
          "cluster_one": {
            "seeds": null <1>
          }
        }
      }
    }
  }
  --------------------------------
  // CONSOLE
  <1> `cluster_one` would be removed from the cluster settings, leaving `cluster_two` intact.
  
  
  [float]
  === Using cross cluster search
  