Get Settings API: Allow to retrieve (just) a specific index / indices settings, closes #810.

modules/elasticsearch/src/main/java/org/elasticsearch/rest/action/RestActionModule.java

@@ -45,6 +45,7 @@ import org.elasticsearch.rest.action.admin.indices.mapping.put.RestPutMappingAct
 import org.elasticsearch.rest.action.admin.indices.open.RestOpenIndexAction;
 import org.elasticsearch.rest.action.admin.indices.optimize.RestOptimizeAction;
 import org.elasticsearch.rest.action.admin.indices.refresh.RestRefreshAction;
+import org.elasticsearch.rest.action.admin.indices.settings.RestGetSettingsAction;
 import org.elasticsearch.rest.action.admin.indices.settings.RestUpdateSettingsAction;
 import org.elasticsearch.rest.action.admin.indices.status.RestIndicesStatusAction;
 import org.elasticsearch.rest.action.admin.indices.template.delete.RestDeleteIndexTemplateAction;
@@ -98,7 +99,10 @@ public class RestActionModule extends AbstractModule {
         bind(RestDeleteIndexAction.class).asEagerSingleton();
         bind(RestCloseIndexAction.class).asEagerSingleton();
         bind(RestOpenIndexAction.class).asEagerSingleton();
+
         bind(RestUpdateSettingsAction.class).asEagerSingleton();
+        bind(RestGetSettingsAction.class).asEagerSingleton();
+
         bind(RestAnalyzeAction.class).asEagerSingleton();
         bind(RestGetIndexTemplateAction.class).asEagerSingleton();
         bind(RestPutIndexTemplateAction.class).asEagerSingleton();

modules/elasticsearch/src/main/java/org/elasticsearch/rest/action/admin/indices/settings/RestGetSettingsAction.java

@@ -0,0 +1,100 @@
+/*
+ * Licensed to Elastic Search and Shay Banon under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. Elastic Search 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.rest.action.admin.indices.settings;
+
+import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.admin.cluster.state.ClusterStateRequest;
+import org.elasticsearch.action.admin.cluster.state.ClusterStateResponse;
+import org.elasticsearch.client.Client;
+import org.elasticsearch.client.Requests;
+import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.cluster.metadata.MetaData;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.settings.SettingsFilter;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.rest.*;
+import org.elasticsearch.rest.action.support.RestXContentBuilder;
+
+import java.io.IOException;
+import java.util.Map;
+
+import static org.elasticsearch.rest.RestRequest.Method.*;
+import static org.elasticsearch.rest.RestStatus.*;
+import static org.elasticsearch.rest.action.support.RestActions.*;
+
+public class RestGetSettingsAction extends BaseRestHandler {
+
+    private final SettingsFilter settingsFilter;
+
+    @Inject public RestGetSettingsAction(Settings settings, Client client, RestController controller, SettingsFilter settingsFilter) {
+        super(settings, client);
+        controller.registerHandler(GET, "/_settings", this);
+        controller.registerHandler(GET, "/{index}/_settings", this);
+
+        this.settingsFilter = settingsFilter;
+    }
+
+    @Override public void handleRequest(final RestRequest request, final RestChannel channel) {
+        final String[] indices = splitIndices(request.param("index"));
+
+        ClusterStateRequest clusterStateRequest = Requests.clusterStateRequest()
+                .filterRoutingTable(true)
+                .filterNodes(true)
+                .filteredIndices(indices);
+
+        client.admin().cluster().state(clusterStateRequest, new ActionListener<ClusterStateResponse>() {
+            @Override public void onResponse(ClusterStateResponse response) {
+                try {
+                    MetaData metaData = response.state().metaData();
+                    XContentBuilder builder = RestXContentBuilder.restContentBuilder(request);
+                    builder.startObject();
+
+                    for (IndexMetaData indexMetaData : metaData) {
+                        builder.startObject(indexMetaData.index());
+
+                        builder.startObject("settings");
+                        Settings settings = settingsFilter.filterSettings(indexMetaData.settings());
+                        for (Map.Entry<String, String> entry : settings.getAsMap().entrySet()) {
+                            builder.field(entry.getKey(), entry.getValue());
+                        }
+                        builder.endObject();
+
+                        builder.endObject();
+                    }
+
+                    builder.endObject();
+
+                    channel.sendResponse(new XContentRestResponse(request, OK, builder));
+                } catch (Exception e) {
+                    onFailure(e);
+                }
+            }
+
+            @Override public void onFailure(Throwable e) {
+                try {
+                    channel.sendResponse(new XContentThrowableRestResponse(request, e));
+                } catch (IOException e1) {
+                    logger.error("Failed to send failure response", e1);
+                }
+            }
+        });
+    }
+}