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Create follower API

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Create follower API

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Creates a follower index.

Description

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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 cross-cluster replication starts replicating operations from the leader index to the follower index.

Request

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PUT /<follower_index>/_ccr/follow?wait_for_active_shards=1
{
  "remote_cluster" : "<remote_cluster>",
  "leader_index" : "<leader_index>"
}

The wait_for_active_shards parameter 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.

Path Parameters

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follower_index (required): (string) the name of the follower index

Request Body

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remote_cluster (required): (string) the remote cluster containing the leader index
leader_index (required): (string) the name of the index in the leader cluster to follow

max_read_request_operation_count: (integer) the maximum number of operations to pull per read from the remote cluster
max_outstanding_read_requests: (long) the maximum number of outstanding reads requests from the remote cluster
max_read_request_size: (byte value) the maximum size in bytes of per read of a batch of operations pulled from the remote cluster
max_write_request_operation_count: (integer) the maximum number of operations per bulk write request executed on the follower
max_write_request_size: (byte value) the maximum total bytes of operations per bulk write request executed on the follower
max_outstanding_write_requests: (integer) the maximum number of outstanding write requests on the follower
max_write_buffer_count: (integer) the maximum number of operations that can be queued for writing; when this limit is reached, reads from the remote cluster will be deferred until the number of queued operations goes below the limit
max_write_buffer_size: (byte value) the maximum total bytes of operations that can be queued for writing; when this limit is reached, reads from the remote cluster will be deferred until the total bytes of queued operations goes below the limit
max_retry_delay: (time value) the maximum time to wait before retrying an operation that failed exceptionally; an exponential backoff strategy is employed when retrying
read_poll_timeout: (time value) the maximum time to wait for new operations on the remote cluster when the follower index is synchronized with the leader index; when the timeout has elapsed, the poll for operations will return to the follower so that it can update some statistics, and then the follower will immediately attempt to read from the leader again

Default values

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The following output from the follow info api describes all the default values for the above described index follow request parameters:

{
  "follower_indices" : [
    {
      "parameters" : {
        "max_read_request_operation_count" : 5120,
        "max_read_request_size" : "32mb",
        "max_outstanding_read_requests" : 12,
        "max_write_request_operation_count" : 5120,
        "max_write_request_size" : "9223372036854775807b",
        "max_outstanding_write_requests" : 9,
        "max_write_buffer_count" : 2147483647,
        "max_write_buffer_size" : "512mb",
        "max_retry_delay" : "500ms",
        "read_poll_timeout" : "1m"
      }
    }
  ]
}

Authorization

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If the Elasticsearch 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.

Example

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This example creates a follower index named follower_index:

PUT /follower_index/_ccr/follow?wait_for_active_shards=1
{
  "remote_cluster" : "remote_cluster",
  "leader_index" : "leader_index",
  "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"
}

The API returns the following result:

{
  "follow_index_created" : true,
  "follow_index_shards_acked" : true,
  "index_following_started" : true
}

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