Introduce forget follower API

buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/RestTestsFromSnippetsTask.groovy

@@ -104,7 +104,7 @@ public class RestTestsFromSnippetsTask extends SnippetsTask {
      * format of the response is incompatible i.e. it is not a JSON object.
      */
     static shouldAddShardFailureCheck(String path) {
-        return path.startsWith('_cat') == false &&  path.startsWith('_ml/datafeeds/') == false
+        return path.startsWith('_cat') == false && path.startsWith('_ml/datafeeds/') == false
     }
 
     /**
@@ -294,7 +294,7 @@ public class RestTestsFromSnippetsTask extends SnippetsTask {
         }
 
         void emitDo(String method, String pathAndQuery, String body,
-                String catchPart, List warnings, boolean inSetup) {
+                String catchPart, List warnings, boolean inSetup, boolean skipShardFailures) {
             def (String path, String query) = pathAndQuery.tokenize('?')
             if (path == null) {
                 path = '' // Catch requests to the root...
@@ -346,7 +346,7 @@ public class RestTestsFromSnippetsTask extends SnippetsTask {
              * section so we have to skip it there. We also omit the assertion
              * from APIs that don't return a JSON object
              */
-            if (false == inSetup && shouldAddShardFailureCheck(path)) {
+            if (false == inSetup && skipShardFailures == false && shouldAddShardFailureCheck(path)) {
                 current.println("  - is_false: _shards.failures")
             }
         }
@@ -394,7 +394,7 @@ public class RestTestsFromSnippetsTask extends SnippetsTask {
                     pathAndQuery = pathAndQuery.substring(1)
                 }
                 emitDo(method, pathAndQuery, body, catchPart, snippet.warnings,
-                    inSetup)
+                    inSetup, snippet.skipShardsFailures)
             }
         }
 

buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/SnippetsTask.groovy

@@ -45,7 +45,7 @@ public class SnippetsTask extends DefaultTask {
     private static final String WARNING = /warning:(.+)/
     private static final String CAT = /(_cat)/
     private static final String TEST_SYNTAX =
-        /(?:$CATCH|$SUBSTITUTION|$SKIP|(continued)|$SETUP|$WARNING) ?/
+        /(?:$CATCH|$SUBSTITUTION|$SKIP|(continued)|$SETUP|$WARNING|(skip_shard_failures)) ?/
 
     /**
      * Action to take on each snippet. Called with a single parameter, an
@@ -233,6 +233,10 @@ public class SnippetsTask extends DefaultTask {
                                 snippet.warnings.add(it.group(7))
                                 return
                             }
+                            if (it.group(8) != null) {
+                                snippet.skipShardsFailures = true
+                                return
+                            }
                             throw new InvalidUserDataException(
                                     "Invalid test marker: $line")
                         }
@@ -329,6 +333,7 @@ public class SnippetsTask extends DefaultTask {
         String setup = null
         boolean curl
         List warnings = new ArrayList()
+        boolean skipShardsFailures = false
 
         @Override
         public String toString() {
@@ -359,6 +364,9 @@ public class SnippetsTask extends DefaultTask {
                 for (String warning in warnings) {
                     result += "[warning:$warning]"
                 }
+                if (skipShardsFailures) {
+                    result += '[skip_shard_failures]'
+                }
             }
             if (testResponse) {
                 result += '// TESTRESPONSE'

client/rest-high-level/src/main/java/org/elasticsearch/client/CcrClient.java

@@ -27,6 +27,7 @@
 import org.elasticsearch.client.ccr.FollowInfoResponse;
 import org.elasticsearch.client.ccr.FollowStatsRequest;
 import org.elasticsearch.client.ccr.FollowStatsResponse;
+import org.elasticsearch.client.ccr.ForgetFollowerRequest;
 import org.elasticsearch.client.ccr.GetAutoFollowPatternRequest;
 import org.elasticsearch.client.ccr.GetAutoFollowPatternResponse;
 import org.elasticsearch.client.ccr.PauseFollowRequest;
@@ -36,6 +37,7 @@
 import org.elasticsearch.client.ccr.ResumeFollowRequest;
 import org.elasticsearch.client.ccr.UnfollowRequest;
 import org.elasticsearch.client.core.AcknowledgedResponse;
+import org.elasticsearch.client.core.BroadcastResponse;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -233,6 +235,48 @@ public void unfollowAsync(UnfollowRequest request,
         );
     }
 
+    /**
+     * Instructs an index acting as a leader index to forget the specified follower index.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/ccr-forget-follower.html">the docs</a> for more details
+     * on the intended usage of this API.
+     *
+     * @param request the request
+     * @param options the request options (e.g., headers), use {@link RequestOptions#DEFAULT} if the defaults are acceptable.
+     * @return the response
+     * @throws IOException if an I/O exception occurs while executing this request
+     */
+    public BroadcastResponse forgetFollower(final ForgetFollowerRequest request, final RequestOptions options) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(
+                request,
+                CcrRequestConverters::forgetFollower,
+                options,
+                BroadcastResponse::fromXContent,
+                Collections.emptySet());
+    }
+
+    /**
+     * Asynchronously instructs an index acting as a leader index to forget the specified follower index.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/ccr-forget-follower.html">the docs</a> for more details
+     * on the intended usage of this API.
+     *
+     * @param request the request
+     * @param options the request options (e.g., headers), use {@link RequestOptions#DEFAULT} if the defaults are acceptable.
+     */
+    public void forgetFollowerAsync(
+            final ForgetFollowerRequest request,
+            final RequestOptions options,
+            final ActionListener<BroadcastResponse> listener) {
+        restHighLevelClient.performRequestAsyncAndParseEntity(
+                request,
+                CcrRequestConverters::forgetFollower,
+                options,
+                BroadcastResponse::fromXContent,
+                listener,
+                Collections.emptySet());
+    }
+
     /**
      * Stores an auto follow pattern.
      *

client/rest-high-level/src/main/java/org/elasticsearch/client/CcrRequestConverters.java

@@ -27,6 +27,7 @@
 import org.elasticsearch.client.ccr.DeleteAutoFollowPatternRequest;
 import org.elasticsearch.client.ccr.FollowInfoRequest;
 import org.elasticsearch.client.ccr.FollowStatsRequest;
+import org.elasticsearch.client.ccr.ForgetFollowerRequest;
 import org.elasticsearch.client.ccr.GetAutoFollowPatternRequest;
 import org.elasticsearch.client.ccr.PauseFollowRequest;
 import org.elasticsearch.client.ccr.PutAutoFollowPatternRequest;
@@ -79,6 +80,17 @@ static Request unfollow(UnfollowRequest unfollowRequest) {
         return new Request(HttpPost.METHOD_NAME, endpoint);
     }
 
+    static Request forgetFollower(final ForgetFollowerRequest forgetFollowerRequest) throws IOException {
+        final String endpoint = new RequestConverters.EndpointBuilder()
+                .addPathPart(forgetFollowerRequest.leaderIndex())
+                .addPathPartAsIs("_ccr")
+                .addPathPartAsIs("forget_follower")
+                .build();
+        final Request request = new Request(HttpPost.METHOD_NAME, endpoint);
+        request.setEntity(createEntity(forgetFollowerRequest, REQUEST_BODY_CONTENT_TYPE));
+        return request;
+    }
+
     static Request putAutoFollowPattern(PutAutoFollowPatternRequest putAutoFollowPatternRequest) throws IOException {
         String endpoint = new RequestConverters.EndpointBuilder()
             .addPathPartAsIs("_ccr", "auto_follow")

client/rest-high-level/src/main/java/org/elasticsearch/client/ccr/ForgetFollowerRequest.java

@@ -0,0 +1,89 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.client.ccr;
+
+import org.elasticsearch.client.Validatable;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+
+import java.io.IOException;
+import java.util.Objects;
+
+/**
+ * Represents a forget follower request. Note that this an expert API intended to be used only when unfollowing a follower index fails to
+ * remove the follower retention leases. Please be sure that you understand the purpose this API before using.
+ */
+public final class ForgetFollowerRequest implements ToXContentObject, Validatable {
+
+    private final String followerCluster;
+
+    private final String followerIndex;
+
+    private final String followerIndexUUID;
+
+    private final String leaderRemoteCluster;
+
+    private final String leaderIndex;
+
+    /**
+     * The name of the leader index.
+     *
+     * @return the name of the leader index
+     */
+    public String leaderIndex() {
+        return leaderIndex;
+    }
+
+    /**
+     * Construct a forget follower request.
+     *
+     * @param followerCluster     the name of the cluster containing the follower index to forget
+     * @param followerIndex       the name of follower index
+     * @param followerIndexUUID   the UUID of the follower index
+     * @param leaderRemoteCluster the alias of the remote cluster containing the leader index from the perspective of the follower index
+     * @param leaderIndex         the name of the leader index
+     */
+    public ForgetFollowerRequest(
+            final String followerCluster,
+            final String followerIndex,
+            final String followerIndexUUID,
+            final String leaderRemoteCluster,
+            final String leaderIndex) {
+        this.followerCluster = Objects.requireNonNull(followerCluster);
+        this.followerIndex = Objects.requireNonNull(followerIndex);
+        this.followerIndexUUID = Objects.requireNonNull(followerIndexUUID);
+        this.leaderRemoteCluster = Objects.requireNonNull(leaderRemoteCluster);
+        this.leaderIndex = Objects.requireNonNull(leaderIndex);
+    }
+
+    @Override
+    public XContentBuilder toXContent(final XContentBuilder builder, final Params params) throws IOException {
+        builder.startObject();
+        {
+            builder.field("follower_cluster", followerCluster);
+            builder.field("follower_index", followerIndex);
+            builder.field("follower_index_uuid", followerIndexUUID);
+            builder.field("leader_remote_cluster", leaderRemoteCluster);
+        }
+        builder.endObject();
+        return builder;
+    }
+
+}