Add _cat/help (halp!)

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

@@ -217,5 +217,6 @@ public class RestActionModule extends AbstractModule {
         bind(RestRecoveryAction.class).asEagerSingleton();
         bind(RestHealthAction.class).asEagerSingleton();
         bind(RestCatAction.class).asEagerSingleton();
+        bind(RestHelpAction.class).asEagerSingleton();
     }
 }

src/main/java/org/elasticsearch/rest/action/cat/RestHelpAction.java

@@ -0,0 +1,60 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon 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.rest.action.cat;
+
+import org.elasticsearch.client.Client;
+import org.elasticsearch.common.inject.Guice;
+import org.elasticsearch.common.inject.Inject;
+import org.elasticsearch.common.inject.Injector;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.rest.*;
+
+import static org.elasticsearch.rest.RestRequest.Method.GET;
+
+
+public class RestHelpAction extends BaseRestHandler {
+
+    @Inject
+    public RestHelpAction(Settings settings, Client client, RestController controller) {
+        super(settings, client);
+        controller.registerHandler(GET, "/_cat/help", this);
+        controller.registerHandler(GET, "/_cat/halp", this);
+    }
+
+    @Override
+    public void handleRequest(final RestRequest request, final RestChannel channel) {
+        // Maybe build this list from a classloader or the RestActionModule injector
+
+        StringBuilder s = new StringBuilder();
+        s.append("Try:\n\n");
+        s.append("/_cat/allocation\n");
+        s.append("/_cat/count\n");
+        s.append("/_cat/count/{index}\n");
+        s.append("/_cat/health\n");
+        s.append("/_cat/indices\n");
+        s.append("/_cat/indices/{index}\n");
+        s.append("/_cat/master\n");
+        s.append("/_cat/nodes\n");
+        s.append("/_cat/recovery\n");
+        s.append("/_cat/shards\n");
+        s.append("/_cat/shards/{index}\n");
+        channel.sendResponse(new StringRestResponse(RestStatus.OK, s.toString()));
+    }
+}