A following index takes out retention leases on its leader index. These retention leases are used to increase the likelihood that the shards of the leader index retain the history of operations that the shards of the following index need to execute replication. When a follower index is converted to a regular index via the unfollow API (either via explicit execution of this API, or implicitly via index lifecycle management), these retention leases are removed. However, removing these retention leases can fail (e.g., if the remote cluster containing the leader index is unavailable). While these retention leases will eventually expire on their own, their extended existence can cause the leader index to hold more history than necessary, and prevent index lifecycle management from performing some operations on the leader index. This API exists to enable manually removing these retention leases when the unfollow API was unable to do so.

This API does not stop replication by a following index. If you use this API targeting a follower index that is still actively following, the following index will add back retention leases on the leader. The only purpose of this API is to handle the case of failure to remove the following retention leases after the unfollow API is invoked.

If the Elasticsearch security features are enabled, you must have manage_leader_index index privileges for the leader index. For more information, see Security privileges.

This example removes the follower retention leases for follower_index from leader_index.

POST /leader_index/_ccr/forget_follower
{
  "follower_cluster" : "follower_cluster",
  "follower_index" : "follower_index",
  "follower_index_uuid" : "vYpnaWPRQB6mNspmoCeYyA",
  "leader_remote_cluster" : "leader_cluster"
}

The API returns the following result:

{
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0,
    "failures" : [ ]
  }
}