OpenSearch/docs/reference/ccr/apis/follow/put-follow.asciidoc

[role="xpack"]
[testenv="platinum"]
[[ccr-put-follow]]
=== Create follower API
++++
<titleabbrev>Create follower</titleabbrev>
++++

Creates a follower index.

[[ccr-put-follow-request]]
==== {api-request-title}

//////////////////////////

[source,console]
--------------------------------------------------
POST /follower_index/_ccr/pause_follow
--------------------------------------------------
// TEARDOWN

//////////////////////////

[source,console]
--------------------------------------------------
PUT /<follower_index>/_ccr/follow?wait_for_active_shards=1
{
  "remote_cluster" : "<remote_cluster>",
  "leader_index" : "<leader_index>"
}
--------------------------------------------------
// TEST[setup:remote_cluster_and_leader_index]
// TEST[s/<follower_index>/follower_index/]
// TEST[s/<remote_cluster>/remote_cluster/]
// TEST[s/<leader_index>/leader_index/]

[[ccr-put-follow-prereqs]]
==== {api-prereq-title}

* If the {es} {security-features} are enabled, you must have `write`, `monitor`,
and `manage_follow_index` index privileges for the follower index. You must have
`read` and `monitor` index privileges for the leader index. You must also have
`manage_ccr` cluster privileges on the cluster that contains the follower index.
For more information, see <<security-privileges>>.

[[ccr-put-follow-desc]]
==== {api-description-title}

This API creates a new follower index that is configured to follow the
referenced leader index. When this API returns, the follower index exists, and
{ccr} starts replicating operations from the leader index to the follower index.

[[ccr-put-follow-path-parms]]
==== {api-path-parms-title}

`<follower_index>`::
  (Required, string) The name of the follower index.

[[ccr-put-follow-query-params]]
==== {api-query-parms-title}

`wait_for_active_shards`::
  (Optional, integer) Specifies the number of shards to wait on being active before
  responding. This defaults to waiting on none of the shards to be active. A
  shard must be restored from the leader index being active. Restoring a
  follower shard requires transferring all the remote Lucene segment files to
  the follower index.


[[ccr-put-follow-request-body]]
==== {api-request-body-title}

`leader_index`::
  (Required, string) The name of the index in the leader cluster to follow.

`remote_cluster`::
  (Required, string) The <<modules-remote-clusters,remote cluster>> containing
  the leader index.

include::../follow-request-body.asciidoc[]

[[ccr-put-follow-examples]]
==== {api-examples-title}

This example creates a follower index named `follower_index`:

[source,console]
--------------------------------------------------
PUT /follower_index/_ccr/follow?wait_for_active_shards=1
{
  "remote_cluster" : "remote_cluster",
  "leader_index" : "leader_index",
  "settings": {
    "index.number_of_replicas": 0
  },
  "max_read_request_operation_count" : 1024,
  "max_outstanding_read_requests" : 16,
  "max_read_request_size" : "1024k",
  "max_write_request_operation_count" : 32768,
  "max_write_request_size" : "16k",
  "max_outstanding_write_requests" : 8,
  "max_write_buffer_count" : 512,
  "max_write_buffer_size" : "512k",
  "max_retry_delay" : "10s",
  "read_poll_timeout" : "30s"
}
--------------------------------------------------
// TEST[setup:remote_cluster_and_leader_index]

The API returns the following result:

[source,console-result]
--------------------------------------------------
{
  "follow_index_created" : true,
  "follow_index_shards_acked" : true,
  "index_following_started" : true
}
--------------------------------------------------