Add HLRC support for enrich stats API (#47306)

This PR also includes HLRC docs for the enrich stats api.

Relates to #32789

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

@@ -24,6 +24,8 @@ import org.elasticsearch.client.enrich.DeletePolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyResponse;
 import org.elasticsearch.client.enrich.PutPolicyRequest;
+import org.elasticsearch.client.enrich.StatsRequest;
+import org.elasticsearch.client.enrich.StatsResponse;
 
 import java.io.IOException;
 import java.util.Collections;
@@ -177,4 +179,49 @@ public final class EnrichClient {
             Collections.emptySet()
         );
     }
+
+    /**
+     * Executes the enrich stats api, which retrieves enrich related stats.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/enrich-policy-apis.html#stats-api">
+     * the docs</a> for more.
+     *
+     * @param request the {@link StatsRequest}
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @return the response
+     * @throws IOException in case there is a problem sending the request or parsing back the response
+     */
+    public StatsResponse stats(StatsRequest request, RequestOptions options) throws IOException {
+        return restHighLevelClient.performRequestAndParseEntity(
+            request,
+            EnrichRequestConverters::stats,
+            options,
+            StatsResponse::fromXContent,
+            Collections.emptySet()
+        );
+    }
+
+    /**
+     * Asynchronously executes the enrich stats api, which retrieves enrich related stats.
+     *
+     * See <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/enrich-policy-apis.html#stats-api">
+     * the docs</a> for more.
+     *
+     * @param request the {@link StatsRequest}
+     * @param options the request options (e.g. headers), use {@link RequestOptions#DEFAULT} if nothing needs to be customized
+     * @param listener the listener to be notified upon request completion
+     * @return cancellable that may be used to cancel the request
+     */
+    public Cancellable statsAsync(StatsRequest request,
+                                  RequestOptions options,
+                                  ActionListener<StatsResponse> listener) {
+        return restHighLevelClient.performRequestAsyncAndParseEntity(
+            request,
+            EnrichRequestConverters::stats,
+            options,
+            StatsResponse::fromXContent,
+            listener,
+            Collections.emptySet()
+        );
+    }
 }

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

@@ -24,6 +24,7 @@ import org.apache.http.client.methods.HttpPut;
 import org.elasticsearch.client.enrich.DeletePolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyRequest;
 import org.elasticsearch.client.enrich.PutPolicyRequest;
+import org.elasticsearch.client.enrich.StatsRequest;
 
 import java.io.IOException;
 
@@ -50,7 +51,7 @@ final class EnrichRequestConverters {
         return new Request(HttpDelete.METHOD_NAME, endpoint);
     }
 
-    static Request getPolicy(GetPolicyRequest getPolicyRequest) throws IOException {
+    static Request getPolicy(GetPolicyRequest getPolicyRequest) {
         String endpoint = new RequestConverters.EndpointBuilder()
             .addPathPartAsIs("_enrich", "policy")
             .addCommaSeparatedPathParts(getPolicyRequest.getNames())
@@ -58,4 +59,11 @@ final class EnrichRequestConverters {
         return new Request(HttpGet.METHOD_NAME, endpoint);
     }
 
+    static Request stats(StatsRequest statsRequest) {
+        String endpoint = new RequestConverters.EndpointBuilder()
+            .addPathPartAsIs("_enrich", "_stats")
+            .build();
+        return new Request(HttpGet.METHOD_NAME, endpoint);
+    }
+
 }

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

@@ -21,7 +21,7 @@ package org.elasticsearch.client.enrich;
 import org.elasticsearch.client.Validatable;
 import org.elasticsearch.common.Strings;
 
-public class DeletePolicyRequest implements Validatable {
+public final class DeletePolicyRequest implements Validatable {
 
     private final String name;
 

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

@@ -33,7 +33,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class PutPolicyRequest implements Validatable, ToXContentObject {
+public final class PutPolicyRequest implements Validatable, ToXContentObject {
 
     private final String name;
     private final String type;

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

@@ -0,0 +1,24 @@
+/*
+ * 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.enrich;
+
+import org.elasticsearch.client.Validatable;
+
+public final class StatsRequest implements Validatable {
+}

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

@@ -0,0 +1,191 @@
+/*
+ * 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.enrich;
+
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.xcontent.ConstructingObjectParser;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.tasks.TaskInfo;
+
+import java.util.List;
+import java.util.Objects;
+
+public final class StatsResponse {
+
+    private static ParseField EXECUTING_POLICIES_FIELD = new ParseField("executing_policies");
+    private static ParseField COORDINATOR_STATS_FIELD = new ParseField("coordinator_stats");
+
+    @SuppressWarnings("unchecked")
+    private static final ConstructingObjectParser<StatsResponse, Void> PARSER = new ConstructingObjectParser<>(
+        "stats_response",
+        true,
+        args -> new StatsResponse((List<ExecutingPolicy>) args[0], (List<CoordinatorStats>) args[1])
+    );
+
+    static {
+        PARSER.declareObjectArray(ConstructingObjectParser.constructorArg(), ExecutingPolicy.PARSER::apply, EXECUTING_POLICIES_FIELD);
+        PARSER.declareObjectArray(ConstructingObjectParser.constructorArg(), CoordinatorStats.PARSER::apply, COORDINATOR_STATS_FIELD);
+    }
+
+    public static StatsResponse fromXContent(XContentParser parser) {
+        return PARSER.apply(parser, null);
+    }
+
+    private final List<ExecutingPolicy> executingPolicies;
+    private final List<CoordinatorStats> coordinatorStats;
+
+    public StatsResponse(List<ExecutingPolicy> executingPolicies, List<CoordinatorStats> coordinatorStats) {
+        this.executingPolicies = executingPolicies;
+        this.coordinatorStats = coordinatorStats;
+    }
+
+    public List<ExecutingPolicy> getExecutingPolicies() {
+        return executingPolicies;
+    }
+
+    public List<CoordinatorStats> getCoordinatorStats() {
+        return coordinatorStats;
+    }
+
+    public static final class CoordinatorStats {
+
+        static ParseField NODE_ID_FIELD = new ParseField("node_id");
+        static ParseField QUEUE_SIZE_FIELD = new ParseField("queue_size");
+        static ParseField REMOTE_REQUESTS_CONCURRENT_FIELD = new ParseField("remote_requests_current");
+        static ParseField REMOTE_REQUESTS_TOTAL_FIELD = new ParseField("remote_requests_total");
+        static ParseField EXECUTED_SEARCHES_FIELD = new ParseField("executed_searches_total");
+
+        private static final ConstructingObjectParser<CoordinatorStats, Void> PARSER = new ConstructingObjectParser<>(
+            "coordinator_stats_item",
+            true,
+            args -> new CoordinatorStats((String) args[0], (int) args[1], (int) args[2], (long) args[3], (long) args[4])
+        );
+
+        static {
+            PARSER.declareString(ConstructingObjectParser.constructorArg(), NODE_ID_FIELD);
+            PARSER.declareInt(ConstructingObjectParser.constructorArg(), QUEUE_SIZE_FIELD);
+            PARSER.declareInt(ConstructingObjectParser.constructorArg(), REMOTE_REQUESTS_CONCURRENT_FIELD);
+            PARSER.declareLong(ConstructingObjectParser.constructorArg(), REMOTE_REQUESTS_TOTAL_FIELD);
+            PARSER.declareLong(ConstructingObjectParser.constructorArg(), EXECUTED_SEARCHES_FIELD);
+        }
+
+        private final String nodeId;
+        private final int queueSize;
+        private final int remoteRequestsCurrent;
+        private final long remoteRequestsTotal;
+        private final long executedSearchesTotal;
+
+        public CoordinatorStats(String nodeId,
+                                int queueSize,
+                                int remoteRequestsCurrent,
+                                long remoteRequestsTotal,
+                                long executedSearchesTotal) {
+            this.nodeId = nodeId;
+            this.queueSize = queueSize;
+            this.remoteRequestsCurrent = remoteRequestsCurrent;
+            this.remoteRequestsTotal = remoteRequestsTotal;
+            this.executedSearchesTotal = executedSearchesTotal;
+        }
+
+        public String getNodeId() {
+            return nodeId;
+        }
+
+        public int getQueueSize() {
+            return queueSize;
+        }
+
+        public int getRemoteRequestsCurrent() {
+            return remoteRequestsCurrent;
+        }
+
+        public long getRemoteRequestsTotal() {
+            return remoteRequestsTotal;
+        }
+
+        public long getExecutedSearchesTotal() {
+            return executedSearchesTotal;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            CoordinatorStats stats = (CoordinatorStats) o;
+            return Objects.equals(nodeId, stats.nodeId) &&
+                queueSize == stats.queueSize &&
+                remoteRequestsCurrent == stats.remoteRequestsCurrent &&
+                remoteRequestsTotal == stats.remoteRequestsTotal &&
+                executedSearchesTotal == stats.executedSearchesTotal;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(nodeId, queueSize, remoteRequestsCurrent, remoteRequestsTotal, executedSearchesTotal);
+        }
+    }
+
+    public static class ExecutingPolicy {
+
+        static ParseField NAME_FIELD = new ParseField("name");
+        static ParseField TASK_FIELD = new ParseField("task");
+
+        private static final ConstructingObjectParser<ExecutingPolicy, Void> PARSER = new ConstructingObjectParser<>(
+            "executing_policy_item",
+            true,
+            args -> new ExecutingPolicy((String) args[0], (TaskInfo) args[1])
+        );
+
+        static {
+            PARSER.declareString(ConstructingObjectParser.constructorArg(), NAME_FIELD);
+            PARSER.declareObject(ConstructingObjectParser.constructorArg(), (p, c) -> TaskInfo.fromXContent(p), TASK_FIELD);
+        }
+
+        private final String name;
+        private final TaskInfo taskInfo;
+
+        public ExecutingPolicy(String name, TaskInfo taskInfo) {
+            this.name = name;
+            this.taskInfo = taskInfo;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public TaskInfo getTaskInfo() {
+            return taskInfo;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            ExecutingPolicy that = (ExecutingPolicy) o;
+            return name.equals(that.name) &&
+                taskInfo.equals(that.taskInfo);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name, taskInfo);
+        }
+    }
+
+}

client/rest-high-level/src/test/java/org/elasticsearch/client/EnrichIT.java

@@ -23,11 +23,15 @@ import org.elasticsearch.client.enrich.DeletePolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyResponse;
 import org.elasticsearch.client.enrich.PutPolicyRequest;
+import org.elasticsearch.client.enrich.StatsRequest;
+import org.elasticsearch.client.enrich.StatsResponse;
 
 import java.util.List;
 
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.greaterThanOrEqualTo;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.notNullValue;
 
 public class EnrichIT extends ESRestHighLevelClientTestCase {
 
@@ -46,6 +50,16 @@ public class EnrichIT extends ESRestHighLevelClientTestCase {
         assertThat(getPolicyResponse.getPolicies().get(0).getMatchField(), equalTo(putPolicyRequest.getMatchField()));
         assertThat(getPolicyResponse.getPolicies().get(0).getEnrichFields(), equalTo(putPolicyRequest.getEnrichFields()));
 
+        StatsRequest statsRequest = new StatsRequest();
+        StatsResponse statsResponse = execute(statsRequest, enrichClient::stats, enrichClient::statsAsync);
+        assertThat(statsResponse.getExecutingPolicies().size(), equalTo(0));
+        assertThat(statsResponse.getCoordinatorStats().size(), equalTo(1));
+        assertThat(statsResponse.getCoordinatorStats().get(0).getNodeId(), notNullValue());
+        assertThat(statsResponse.getCoordinatorStats().get(0).getQueueSize(), greaterThanOrEqualTo(0));
+        assertThat(statsResponse.getCoordinatorStats().get(0).getRemoteRequestsCurrent(), greaterThanOrEqualTo(0));
+        assertThat(statsResponse.getCoordinatorStats().get(0).getRemoteRequestsTotal(), greaterThanOrEqualTo(0L));
+        assertThat(statsResponse.getCoordinatorStats().get(0).getExecutedSearchesTotal(), greaterThanOrEqualTo(0L));
+
         DeletePolicyRequest deletePolicyRequest = new DeletePolicyRequest("my-policy");
         AcknowledgedResponse deletePolicyResponse =
             execute(deletePolicyRequest, enrichClient::deletePolicy, enrichClient::deletePolicyAsync);

client/rest-high-level/src/test/java/org/elasticsearch/client/EnrichRequestConvertersTests.java

@@ -25,6 +25,7 @@ import org.elasticsearch.client.enrich.DeletePolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyRequest;
 import org.elasticsearch.client.enrich.PutPolicyRequest;
 import org.elasticsearch.client.enrich.PutPolicyRequestTests;
+import org.elasticsearch.client.enrich.StatsRequest;
 import org.elasticsearch.test.ESTestCase;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -42,7 +43,7 @@ public class EnrichRequestConvertersTests extends ESTestCase {
         RequestConvertersTests.assertToXContentBody(request, result.getEntity());
     }
 
-    public void testDeletePolicy() throws Exception {
+    public void testDeletePolicy() {
         DeletePolicyRequest request = new DeletePolicyRequest(randomAlphaOfLength(4));
         Request result = EnrichRequestConverters.deletePolicy(request);
 
@@ -52,7 +53,7 @@ public class EnrichRequestConvertersTests extends ESTestCase {
         assertThat(result.getEntity(), nullValue());
     }
 
-    public void testGetPolicy() throws Exception {
+    public void testGetPolicy() {
         GetPolicyRequest request = new GetPolicyRequest(randomAlphaOfLength(4));
         Request result = EnrichRequestConverters.getPolicy(request);
 
@@ -78,4 +79,14 @@ public class EnrichRequestConvertersTests extends ESTestCase {
         assertThat(result.getEntity(), nullValue());
     }
 
+    public void testStats() {
+        StatsRequest request = new StatsRequest();
+        Request result = EnrichRequestConverters.stats(request);
+
+        assertThat(result.getMethod(), equalTo(HttpGet.METHOD_NAME));
+        assertThat(result.getEndpoint(), equalTo("/_enrich/_stats"));
+        assertThat(result.getParameters().size(), equalTo(0));
+        assertThat(result.getEntity(), nullValue());
+    }
+
 }

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/EnrichDocumentationIT.java

@@ -29,6 +29,10 @@ import org.elasticsearch.client.enrich.NamedPolicy;
 import org.elasticsearch.client.enrich.GetPolicyRequest;
 import org.elasticsearch.client.enrich.GetPolicyResponse;
 import org.elasticsearch.client.enrich.PutPolicyRequest;
+import org.elasticsearch.client.enrich.StatsRequest;
+import org.elasticsearch.client.enrich.StatsResponse;
+import org.elasticsearch.client.enrich.StatsResponse.CoordinatorStats;
+import org.elasticsearch.client.enrich.StatsResponse.ExecutingPolicy;
 import org.junit.After;
 
 import java.util.List;
@@ -193,4 +197,52 @@ public class EnrichDocumentationIT extends ESRestHighLevelClientTestCase {
         assertTrue(latch.await(30L, TimeUnit.SECONDS));
     }
 
+    public void testStats() throws Exception {
+        RestHighLevelClient client = highLevelClient();
+
+        // tag::enrich-stats-request
+        StatsRequest statsRequest = new StatsRequest();
+        // end::enrich-stats-request
+
+        // tag::enrich-stats-execute
+        StatsResponse statsResponse =
+            client.enrich().stats(statsRequest, RequestOptions.DEFAULT);
+        // end::enrich-stats-execute
+
+        // tag::enrich-stats-response
+        List<ExecutingPolicy> executingPolicies =
+            statsResponse.getExecutingPolicies();  // <1>
+        List<CoordinatorStats> coordinatorStats =
+            statsResponse.getCoordinatorStats();  // <2>
+        // end::enrich-stats-response
+
+        // tag::enrich-stats-execute-listener
+        ActionListener<StatsResponse> listener = new ActionListener<>() {
+            @Override
+            public void onResponse(StatsResponse response) { // <1>
+                List<ExecutingPolicy> executingPolicies =
+                    statsResponse.getExecutingPolicies();
+                List<CoordinatorStats> coordinatorStats =
+                    statsResponse.getCoordinatorStats();
+            }
+
+            @Override
+            public void onFailure(Exception e) {
+                // <2>
+            }
+        };
+        // end::enrich-stats-execute-listener
+
+        // Replace the empty listener by a blocking listener in test
+        final CountDownLatch latch = new CountDownLatch(1);
+        listener = new LatchedActionListener<>(listener, latch);
+
+        // tag::enrich-stats-execute-async
+        client.enrich().statsAsync(statsRequest, RequestOptions.DEFAULT,
+            listener); // <1>
+        // end::enrich-stats-execute-async
+
+        assertTrue(latch.await(30L, TimeUnit.SECONDS));
+    }
+
 }

client/rest-high-level/src/test/java/org/elasticsearch/client/enrich/StatsResponseTests.java

@@ -0,0 +1,98 @@
+/*
+ * 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.enrich;
+
+import org.elasticsearch.client.AbstractResponseTestCase;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.common.xcontent.XContentType;
+import org.elasticsearch.tasks.TaskId;
+import org.elasticsearch.tasks.TaskInfo;
+import org.elasticsearch.xpack.core.enrich.action.EnrichStatsAction;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+
+import static org.hamcrest.Matchers.equalTo;
+
+public class StatsResponseTests extends AbstractResponseTestCase<EnrichStatsAction.Response, StatsResponse> {
+
+    @Override
+    protected EnrichStatsAction.Response createServerTestInstance(XContentType xContentType) {
+        int numExecutingPolicies = randomIntBetween(0, 16);
+        List<EnrichStatsAction.Response.ExecutingPolicy> executingPolicies = new ArrayList<>(numExecutingPolicies);
+        for (int i = 0; i < numExecutingPolicies; i++) {
+            TaskInfo taskInfo = randomTaskInfo();
+            executingPolicies.add(new EnrichStatsAction.Response.ExecutingPolicy(randomAlphaOfLength(4), taskInfo));
+        }
+        int numCoordinatingStats = randomIntBetween(0, 16);
+        List<EnrichStatsAction.Response.CoordinatorStats> coordinatorStats = new ArrayList<>(numCoordinatingStats);
+        for (int i = 0; i < numCoordinatingStats; i++) {
+            EnrichStatsAction.Response.CoordinatorStats stats = new EnrichStatsAction.Response.CoordinatorStats(
+                randomAlphaOfLength(4), randomIntBetween(0, 8096), randomIntBetween(0, 8096), randomNonNegativeLong(),
+                randomNonNegativeLong());
+            coordinatorStats.add(stats);
+        }
+        return new EnrichStatsAction.Response(executingPolicies, coordinatorStats);
+    }
+
+    @Override
+    protected StatsResponse doParseToClientInstance(XContentParser parser) throws IOException {
+        return StatsResponse.fromXContent(parser);
+    }
+
+    @Override
+    protected void assertInstances(EnrichStatsAction.Response serverTestInstance, StatsResponse clientInstance) {
+        assertThat(clientInstance.getExecutingPolicies().size(), equalTo(serverTestInstance.getExecutingPolicies().size()));
+        for (int i = 0; i < clientInstance.getExecutingPolicies().size(); i++) {
+            StatsResponse.ExecutingPolicy actual = clientInstance.getExecutingPolicies().get(i);
+            EnrichStatsAction.Response.ExecutingPolicy expected = serverTestInstance.getExecutingPolicies().get(i);
+            assertThat(actual.getName(), equalTo(expected.getName()));
+            assertThat(actual.getTaskInfo(), equalTo(actual.getTaskInfo()));
+        }
+
+        assertThat(clientInstance.getCoordinatorStats().size(), equalTo(serverTestInstance.getCoordinatorStats().size()));
+        for (int i = 0; i < clientInstance.getCoordinatorStats().size(); i++) {
+            StatsResponse.CoordinatorStats actual = clientInstance.getCoordinatorStats().get(i);
+            EnrichStatsAction.Response.CoordinatorStats expected = serverTestInstance.getCoordinatorStats().get(i);
+            assertThat(actual.getNodeId(), equalTo(expected.getNodeId()));
+            assertThat(actual.getQueueSize(), equalTo(expected.getQueueSize()));
+            assertThat(actual.getRemoteRequestsCurrent(), equalTo(expected.getRemoteRequestsCurrent()));
+            assertThat(actual.getRemoteRequestsTotal(), equalTo(expected.getRemoteRequestsTotal()));
+            assertThat(actual.getExecutedSearchesTotal(), equalTo(expected.getExecutedSearchesTotal()));
+        }
+    }
+
+    private static TaskInfo randomTaskInfo() {
+        TaskId taskId = new TaskId(randomAlphaOfLength(5), randomLong());
+        String type = randomAlphaOfLength(5);
+        String action = randomAlphaOfLength(5);
+        String description = randomAlphaOfLength(5);
+        long startTime = randomLong();
+        long runningTimeNanos = randomLong();
+        boolean cancellable = randomBoolean();
+        TaskId parentTaskId = TaskId.EMPTY_TASK_ID;
+        Map<String, String> headers = randomBoolean() ?
+            Collections.emptyMap() :
+            Collections.singletonMap(randomAlphaOfLength(5), randomAlphaOfLength(5));
+        return new TaskInfo(taskId, type, action, description, null, startTime, runningTimeNanos, cancellable, parentTaskId, headers);
+    }
+}

docs/java-rest/high-level/enrich/stats.asciidoc

@@ -0,0 +1,33 @@
+--
+:api: enrich-stats
+:request: StatsRequest
+:response: StatsResponse
+--
+
+[id="{upid}-{api}"]
+=== Stats API
+
+[id="{upid}-{api}-request"]
+==== Request
+
+The stats API returns enrich related stats.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-request]
+--------------------------------------------------
+
+[id="{upid}-{api}-response"]
+==== Response
+
+The returned +{response}+ includes enrich related stats.
+
+["source","java",subs="attributes,callouts,macros"]
+--------------------------------------------------
+include-tagged::{doc-tests-file}[{api}-response]
+--------------------------------------------------
+<1> List of policies that are currently executing with
+    additional details.
+<2> List of coordinator stats per ingest node.
+
+include::../execution.asciidoc[]

docs/java-rest/high-level/supported-apis.asciidoc

@@ -613,7 +613,9 @@ The Java High Level REST Client supports the following Enrich APIs:
 * <<{upid}-enrich-put-policy>>
 * <<{upid}-enrich-delete-policy>>
 * <<{upid}-enrich-get-policy>>
+* <<{upid}-enrich-stats-policy>>
 
 include::enrich/put_policy.asciidoc[]
 include::enrich/delete_policy.asciidoc[]
 include::enrich/get_policy.asciidoc[]
+include::enrich/stats.asciidoc[]

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/enrich/action/EnrichStatsAction.java

@@ -18,8 +18,6 @@ import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.tasks.TaskInfo;
 
 import java.io.IOException;
-import java.io.UncheckedIOException;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 
@@ -81,26 +79,18 @@ public class EnrichStatsAction extends ActionType<EnrichStatsAction.Response> {
         public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
             builder.startObject();
             builder.startArray("executing_policies");
-            executingPolicies.stream().sorted(Comparator.comparing(ExecutingPolicy::getName)).forEachOrdered(policy -> {
-                try {
-                    builder.startObject();
-                    policy.toXContent(builder, params);
-                    builder.endObject();
-                } catch (IOException e) {
-                    throw new UncheckedIOException(e);
-                }
-            });
+            for (ExecutingPolicy policy : executingPolicies) {
+                builder.startObject();
+                policy.toXContent(builder, params);
+                builder.endObject();
+            }
             builder.endArray();
             builder.startArray("coordinator_stats");
-            coordinatorStats.stream().sorted(Comparator.comparing(CoordinatorStats::getNodeId)).forEachOrdered(entry -> {
-                try {
-                    builder.startObject();
-                    entry.toXContent(builder, params);
-                    builder.endObject();
-                } catch (IOException e) {
-                    throw new UncheckedIOException(e);
-                }
-            });
+            for (CoordinatorStats entry : coordinatorStats) {
+                builder.startObject();
+                entry.toXContent(builder, params);
+                builder.endObject();
+            }
             builder.endArray();
             builder.endObject();
             return builder;

x-pack/plugin/enrich/src/main/java/org/elasticsearch/xpack/enrich/action/TransportEnrichStatsAction.java

@@ -26,6 +26,7 @@ import org.elasticsearch.xpack.core.enrich.action.EnrichStatsAction.Response.Exe
 import org.elasticsearch.xpack.core.enrich.action.ExecuteEnrichPolicyAction;
 
 import java.io.IOException;
+import java.util.Comparator;
 import java.util.List;
 import java.util.stream.Collectors;
 
@@ -76,11 +77,13 @@ public class TransportEnrichStatsAction extends TransportMasterNodeAction<Enrich
 
                 List<CoordinatorStats> coordinatorStats = response.getNodes().stream()
                     .map(EnrichCoordinatorStatsAction.NodeResponse::getCoordinatorStats)
+                    .sorted(Comparator.comparing(CoordinatorStats::getNodeId))
                     .collect(Collectors.toList());
                 List<ExecutingPolicy> policyExecutionTasks = taskManager.getTasks().values().stream()
                     .filter(t -> t.getAction().equals(ExecuteEnrichPolicyAction.NAME))
                     .map(t -> t.taskInfo(clusterService.localNode().getId(), true))
                     .map(t -> new ExecutingPolicy(t.getDescription(), t))
+                    .sorted(Comparator.comparing(ExecutingPolicy::getName))
                     .collect(Collectors.toList());
                 listener.onResponse(new EnrichStatsAction.Response(policyExecutionTasks, coordinatorStats));
             },