The Forget Follower API allows you to manually remove the follower retention leases from the leader. Note that these retention leases are automatically managed by the following index. This API exists only for cases when invoking the unfollow API on the follower index is unable to remove the follower retention leases.

final ForgetFollowerRequest request = new ForgetFollowerRequest(
        followerCluster, 
        followerIndex, 
        followerIndexUUID, 
        leaderCluster, 
        leaderIndex); 

The returned BroadcastResponse indicates if the response was successful.

final BroadcastResponse.Shards shards = response.shards(); 
final int total = shards.total(); 
final int successful = shards.successful(); 
final int skipped = shards.skipped(); 
final int failed = shards.failed(); 
shards.failures().forEach(failure -> {}); 

When executing a ForgetFollowerRequest in the following manner, the client waits for the BroadcastResponse to be returned before continuing with code execution:

final BroadcastResponse response = client
        .ccr()
        .forgetFollower(request, RequestOptions.DEFAULT);

Synchronous calls may throw an IOException in case of either failing to parse the REST response in the high-level REST client, the request times out or similar cases where there is no response coming back from the server.

In cases where the server returns a 4xx or 5xx error code, the high-level client tries to parse the response body error details instead and then throws a generic ElasticsearchException and adds the original ResponseException as a suppressed exception to it.

Executing a ForgetFollowerRequest can also be done in an asynchronous fashion so that the client can return directly. Users need to specify how the response or potential failures will be handled by passing the request and a listener to the asynchronous ccr-forget-follower method:

client.ccr().forgetFollowerAsync(
        request,
        RequestOptions.DEFAULT,
        listener); 

The asynchronous method does not block and returns immediately. Once it is completed the ActionListener is called back using the onResponse method if the execution successfully completed or using the onFailure method if it failed. Failure scenarios and expected exceptions are the same as in the synchronous execution case.

A typical listener for ccr-forget-follower looks like:

ActionListener<BroadcastResponse> listener =
        new ActionListener<BroadcastResponse>() {

            @Override
            public void onResponse(final BroadcastResponse response) {
                final BroadcastResponse.Shards shards = 
                        response.shards();
                final int total = shards.total();
                final int successful = shards.successful();
                final int skipped = shards.skipped();
                final int failed = shards.failed();
                shards.failures().forEach(failure -> {});
            }

            @Override
            public void onFailure(final Exception e) {
                
            }

        };