Add enrich policy GET API (#41384)

This commit wires up the Rest calls and Transport calls for GET enrich
policy, as well as tests and rest spec additions.

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

@@ -0,0 +1,132 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.core.enrich.action;
+
+import org.elasticsearch.action.Action;
+import org.elasticsearch.action.ActionRequestValidationException;
+import org.elasticsearch.action.ActionResponse;
+import org.elasticsearch.action.support.master.MasterNodeReadRequest;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.xpack.core.enrich.EnrichPolicy;
+
+import java.io.IOException;
+import java.util.Objects;
+
+public class GetEnrichPolicyAction extends Action<GetEnrichPolicyAction.Response> {
+
+    public static final GetEnrichPolicyAction INSTANCE = new GetEnrichPolicyAction();
+    public static final String NAME = "cluster:admin/xpack/enrich/get";
+
+    private GetEnrichPolicyAction() {
+        super(NAME);
+    }
+
+    @Override
+    public Response newResponse() {
+        throw new UnsupportedOperationException("usage of Streamable is to be replaced by Writeable");
+    }
+
+    @Override
+    public Writeable.Reader<Response> getResponseReader() {
+        return Response::new;
+    }
+
+    public static class Request extends MasterNodeReadRequest<Request> {
+
+        private String name;
+
+        public Request(String name) {
+            this.name = name;
+        }
+
+        public Request(StreamInput in) throws IOException {
+            super(in);
+            this.name = in.readOptionalString();
+        }
+
+        @Override
+        public ActionRequestValidationException validate() {
+            return null;
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            super.writeTo(out);
+            out.writeOptionalString(name);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Request request = (Request) o;
+            return Objects.equals(name, request.name);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(name);
+        }
+    }
+
+    public static class Response extends ActionResponse implements ToXContentObject {
+
+        private final EnrichPolicy policy;
+
+        public Response(EnrichPolicy policy) {
+            this.policy = Objects.requireNonNull(policy, "policy cannot be null");
+        }
+
+        public Response(StreamInput in) throws IOException {
+            policy = new EnrichPolicy(in);
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            policy.writeTo(out);
+        }
+
+        @Override
+        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+            builder.startObject();
+            {
+                policy.toXContent(builder, params);
+            }
+            builder.endObject();
+
+            return builder;
+        }
+
+        public EnrichPolicy getPolicy() {
+            return policy;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            Response response = (Response) o;
+            return policy.equals(response.policy);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(policy);
+        }
+    }
+}

x-pack/plugin/enrich/qa/rest/src/test/resources/rest-api-spec/test/enrich/10_basic.yml

@@ -16,6 +16,14 @@
         name: policy-crud
   - is_true: acknowledged
 
+  - do:
+      enrich.get_policy:
+        name: policy-crud
+  - match: { type: exact_match }
+  - match: { indices: ["bar*"] }
+  - match: { enrich_key: baz }
+  - match: { enrich_values: ["a", "b"] }
+
   - do:
       enrich.list_policy: {}
   - length: { policies: 1 }

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

@@ -33,14 +33,17 @@ import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.watcher.ResourceWatcherService;
 import org.elasticsearch.xpack.core.enrich.action.DeleteEnrichPolicyAction;
 import org.elasticsearch.xpack.core.enrich.action.ExecuteEnrichPolicyAction;
+import org.elasticsearch.xpack.core.enrich.action.GetEnrichPolicyAction;
 import org.elasticsearch.xpack.core.enrich.action.ListEnrichPolicyAction;
 import org.elasticsearch.xpack.core.enrich.action.PutEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.action.TransportDeleteEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.action.TransportExecuteEnrichPolicyAction;
+import org.elasticsearch.xpack.enrich.action.TransportGetEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.action.TransportListEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.action.TransportPutEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.rest.RestDeleteEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.rest.RestExecuteEnrichPolicyAction;
+import org.elasticsearch.xpack.enrich.rest.RestGetEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.rest.RestListEnrichPolicyAction;
 import org.elasticsearch.xpack.enrich.rest.RestPutEnrichPolicyAction;
 
@@ -81,6 +84,7 @@ public class EnrichPlugin extends Plugin implements ActionPlugin, IngestPlugin {
         }
 
         return Arrays.asList(
+            new ActionHandler<>(GetEnrichPolicyAction.INSTANCE, TransportGetEnrichPolicyAction.class),
             new ActionHandler<>(DeleteEnrichPolicyAction.INSTANCE, TransportDeleteEnrichPolicyAction.class),
             new ActionHandler<>(ListEnrichPolicyAction.INSTANCE, TransportListEnrichPolicyAction.class),
             new ActionHandler<>(PutEnrichPolicyAction.INSTANCE, TransportPutEnrichPolicyAction.class),
@@ -97,6 +101,7 @@ public class EnrichPlugin extends Plugin implements ActionPlugin, IngestPlugin {
         }
 
         return Arrays.asList(
+            new RestGetEnrichPolicyAction(settings, restController),
             new RestDeleteEnrichPolicyAction(settings, restController),
             new RestListEnrichPolicyAction(settings, restController),
             new RestPutEnrichPolicyAction(settings, restController),

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

@@ -0,0 +1,71 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.enrich.action;
+
+import org.elasticsearch.ResourceNotFoundException;
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.support.ActionFilters;
+import org.elasticsearch.action.support.master.TransportMasterNodeReadAction;
+import org.elasticsearch.cluster.ClusterState;
+import org.elasticsearch.cluster.block.ClusterBlockException;
+import org.elasticsearch.cluster.block.ClusterBlockLevel;
+import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
+import org.elasticsearch.cluster.service.ClusterService;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.threadpool.ThreadPool;
+import org.elasticsearch.transport.TransportService;
+import org.elasticsearch.xpack.core.enrich.EnrichPolicy;
+import org.elasticsearch.xpack.core.enrich.action.GetEnrichPolicyAction;
+import org.elasticsearch.xpack.enrich.EnrichStore;
+
+import java.io.IOException;
+
+public class TransportGetEnrichPolicyAction extends TransportMasterNodeReadAction<GetEnrichPolicyAction.Request,
+    GetEnrichPolicyAction.Response> {
+
+    @Inject
+    public TransportGetEnrichPolicyAction(TransportService transportService,
+                                               ClusterService clusterService,
+                                               ThreadPool threadPool,
+                                               ActionFilters actionFilters,
+                                               IndexNameExpressionResolver indexNameExpressionResolver) {
+        super(GetEnrichPolicyAction.NAME, transportService, clusterService, threadPool, actionFilters,
+            GetEnrichPolicyAction.Request::new, indexNameExpressionResolver);
+    }
+
+    @Override
+    protected String executor() {
+        return ThreadPool.Names.SAME;
+    }
+
+    @Override
+    protected GetEnrichPolicyAction.Response newResponse() {
+        throw new UnsupportedOperationException("usage of Streamable is to be replaced by Writeable");
+    }
+
+    @Override
+    protected GetEnrichPolicyAction.Response read(StreamInput in) throws IOException {
+        return new GetEnrichPolicyAction.Response(in);
+    }
+
+    @Override
+    protected void masterOperation(GetEnrichPolicyAction.Request request,
+                                   ClusterState state,
+                                   ActionListener<GetEnrichPolicyAction.Response> listener) throws Exception {
+        final EnrichPolicy policy = EnrichStore.getPolicy(request.getName(), state);
+        if (policy == null) {
+            throw new ResourceNotFoundException("Policy [{}] was not found", request.getName());
+        }
+        listener.onResponse(new GetEnrichPolicyAction.Response(policy));
+    }
+
+    @Override
+    protected ClusterBlockException checkBlock(GetEnrichPolicyAction.Request request, ClusterState state) {
+        return state.blocks().globalBlockedException(ClusterBlockLevel.METADATA_READ);
+    }
+
+}

x-pack/plugin/enrich/src/main/java/org/elasticsearch/xpack/enrich/rest/RestGetEnrichPolicyAction.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.enrich.rest;
+
+import org.elasticsearch.client.node.NodeClient;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.rest.BaseRestHandler;
+import org.elasticsearch.rest.RestController;
+import org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.action.RestToXContentListener;
+import org.elasticsearch.xpack.core.enrich.action.GetEnrichPolicyAction;
+
+import java.io.IOException;
+
+public class RestGetEnrichPolicyAction extends BaseRestHandler {
+
+    public RestGetEnrichPolicyAction(final Settings settings, final RestController controller) {
+        super(settings);
+        controller.registerHandler(RestRequest.Method.GET, "/_enrich/policy/{name}", this);
+    }
+
+    @Override
+    public String getName() {
+        return "get_enrich_policy";
+    }
+
+    @Override
+    protected RestChannelConsumer prepareRequest(final RestRequest restRequest, final NodeClient client) throws IOException {
+        final GetEnrichPolicyAction.Request request = new GetEnrichPolicyAction.Request(restRequest.param("name"));
+        return channel -> client.execute(GetEnrichPolicyAction.INSTANCE, request, new RestToXContentListener<>(channel));
+    }
+}

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/action/GetEnrichPolicyActionRequestTests.java

@@ -0,0 +1,23 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.enrich.action;
+
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.test.AbstractWireSerializingTestCase;
+import org.elasticsearch.xpack.core.enrich.action.GetEnrichPolicyAction;
+
+public class GetEnrichPolicyActionRequestTests extends AbstractWireSerializingTestCase<GetEnrichPolicyAction.Request> {
+
+    @Override
+    protected GetEnrichPolicyAction.Request createTestInstance() {
+        return new GetEnrichPolicyAction.Request(randomAlphaOfLength(5));
+    }
+
+    @Override
+    protected Writeable.Reader<GetEnrichPolicyAction.Request> instanceReader() {
+        return GetEnrichPolicyAction.Request::new;
+    }
+}

x-pack/plugin/enrich/src/test/java/org/elasticsearch/xpack/enrich/action/GetEnrichPolicyActionResponseTests.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.xpack.enrich.action;
+
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.xcontent.XContentParser;
+import org.elasticsearch.common.xcontent.XContentType;
+import org.elasticsearch.test.AbstractSerializingTestCase;
+import org.elasticsearch.xpack.core.enrich.EnrichPolicy;
+import org.elasticsearch.xpack.core.enrich.action.GetEnrichPolicyAction;
+
+import java.io.IOException;
+
+import static org.elasticsearch.xpack.enrich.EnrichPolicyTests.assertEqualPolicies;
+import static org.elasticsearch.xpack.enrich.EnrichPolicyTests.randomEnrichPolicy;
+
+public class GetEnrichPolicyActionResponseTests extends AbstractSerializingTestCase<GetEnrichPolicyAction.Response> {
+
+    @Override
+    protected GetEnrichPolicyAction.Response doParseInstance(XContentParser parser) throws IOException {
+        EnrichPolicy policy = EnrichPolicy.fromXContent(parser);
+        return new GetEnrichPolicyAction.Response(policy);
+    }
+
+    @Override
+    protected GetEnrichPolicyAction.Response createTestInstance() {
+        EnrichPolicy policy = randomEnrichPolicy(XContentType.JSON);
+        return new GetEnrichPolicyAction.Response(policy);
+    }
+
+    @Override
+    protected Writeable.Reader<GetEnrichPolicyAction.Response> instanceReader() {
+        return GetEnrichPolicyAction.Response::new;
+    }
+
+    @Override
+    protected void assertEqualInstances(GetEnrichPolicyAction.Response expectedInstance, GetEnrichPolicyAction.Response newInstance) {
+        assertNotSame(expectedInstance, newInstance);
+        // the tests shuffle around the policy query source xcontent type, so this is needed here
+        assertEqualPolicies(expectedInstance.getPolicy(), newInstance.getPolicy());
+    }
+}

x-pack/plugin/src/test/resources/rest-api-spec/api/enrich.get_policy.json

@@ -0,0 +1,19 @@
+{
+  "enrich.get_policy": {
+    "documentation": "https://www.elastic.co/guide/en/elasticsearch/reference/current/enrich-get-policy.html",
+    "methods": [ "GET" ],
+    "url": {
+      "path": "/_enrich/policy/{name}",
+      "paths": ["/_enrich/policy/{name}"],
+      "parts": {
+        "name": {
+          "type" : "string",
+          "description" : "The name of the enrich policy"
+        }
+      },
+      "params": {
+      }
+    },
+    "body": null
+  }
+}