package org.apache.helix.rest.server.resources.zookeeper; /* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF 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. */ import java.util.List; import java.util.Map; import javax.ws.rs.DefaultValue; import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.PathParam; import javax.ws.rs.QueryParam; import javax.ws.rs.WebApplicationException; import javax.ws.rs.core.Response; import com.google.common.base.Enums; import com.google.common.collect.ImmutableMap; import org.apache.helix.AccessOption; import org.apache.helix.BaseDataAccessor; import org.apache.helix.manager.zk.ZKUtil; import org.apache.helix.msdcommon.util.ZkValidationUtil; import org.apache.helix.rest.common.ContextPropertyKeys; import org.apache.helix.rest.server.ServerContext; import org.apache.helix.rest.server.resources.AbstractResource; import org.apache.zookeeper.data.Stat; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * ZooKeeperAccessor provides methods for accessing ZooKeeper resources (ZNodes). * It provides basic ZooKeeper features supported by ZkClient. */ @Path("/zookeeper") public class ZooKeeperAccessor extends AbstractResource { private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperAccessor.class.getName()); private BaseDataAccessor<byte[]> _zkBaseDataAccessor; public enum ZooKeeperCommand { exists, getBinaryData, getStringData, getChildren, getStat } @GET @Path("{path: .+}") public Response get(@PathParam("path") String path, @QueryParam("command") String commandStr) { ZooKeeperCommand cmd = getZooKeeperCommandIfPresent(commandStr); if (cmd == null) { return badRequest("Invalid ZooKeeper command: " + commandStr); } // Lazily initialize ZkBaseDataAccessor ServerContext _serverContext = (ServerContext) _application.getProperties().get(ContextPropertyKeys.SERVER_CONTEXT.name()); _zkBaseDataAccessor = _serverContext.getByteArrayZkBaseDataAccessor(); // Need to prepend a "/" since JAX-RS regex removes it path = "/" + path; // Check that the path supplied is valid if (!ZkValidationUtil.isPathValid(path)) { String errMsg = "The given path is not a valid ZooKeeper path: " + path; LOG.info(errMsg); return badRequest(errMsg); } switch (cmd) { case exists: return exists(_zkBaseDataAccessor, path); case getBinaryData: return getBinaryData(_zkBaseDataAccessor, path); case getStringData: return getStringData(_zkBaseDataAccessor, path); case getChildren: return getChildren(_zkBaseDataAccessor, path); case getStat: return getStat(_zkBaseDataAccessor, path); default: String errMsg = "Unsupported command: " + commandStr; LOG.error(errMsg); return badRequest(errMsg); } } /** * Checks if a ZNode exists in the given path. * @param zkBaseDataAccessor * @param path * @return true if a ZNode exists, false otherwise */ private Response exists(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) { Map<String, Boolean> result = ImmutableMap.of(ZooKeeperCommand.exists.name(), zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)); return JSONRepresentation(result); } /** * Returns a response containing the binary data and Stat. * @param zkBaseDataAccessor * @param path * @return */ private Response getBinaryData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) { Stat stat = new Stat(); byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat); Map<String, Object> binaryResult = ImmutableMap .of(ZooKeeperCommand.getBinaryData.name(), bytes, ZooKeeperCommand.getStat.name(), ZKUtil.fromStatToMap(stat)); // Note: this serialization (using ObjectMapper) will convert this byte[] into // a Base64 String! The REST client (user) must convert the resulting String back into // a byte[] using Base64. return JSONRepresentation(binaryResult); } /** * Returns a response containing the string data and Stat. * @param zkBaseDataAccessor * @param path * @return */ private Response getStringData(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) { Stat stat = new Stat(); byte[] bytes = readBinaryDataFromZK(zkBaseDataAccessor, path, stat); Map<String, Object> stringResult = ImmutableMap .of(ZooKeeperCommand.getStringData.name(), new String(bytes), ZooKeeperCommand.getStat.name(), ZKUtil.fromStatToMap(stat)); return JSONRepresentation(stringResult); } /** * Returns byte[] from ZooKeeper. * @param zkBaseDataAccessor * @param path * @return */ private byte[] readBinaryDataFromZK(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path, Stat stat) { if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) { return zkBaseDataAccessor.get(path, stat, AccessOption.PERSISTENT); } else { throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND) .entity(String.format("The ZNode at path %s does not exist!", path)).build()); } } /** * Returns a list of children ZNode names given the path for the parent ZNode. * @param zkBaseDataAccessor * @param path * @return list of child ZNodes */ private Response getChildren(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) { if (zkBaseDataAccessor.exists(path, AccessOption.PERSISTENT)) { Map<String, List<String>> result = ImmutableMap.of(ZooKeeperCommand.getChildren.name(), zkBaseDataAccessor.getChildNames(path, AccessOption.PERSISTENT)); return JSONRepresentation(result); } else { throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND) .entity(String.format("The ZNode at path %s does not exist", path)).build()); } } /** * Returns the ZNode Stat object given the path. * @param zkBaseDataAccessor * @param path * @return */ private Response getStat(BaseDataAccessor<byte[]> zkBaseDataAccessor, String path) { Stat stat = zkBaseDataAccessor.getStat(path, AccessOption.PERSISTENT); if (stat == null) { throw new WebApplicationException(Response.status(Response.Status.NOT_FOUND) .entity(String.format("The ZNode at path %s does not exist!", path)).build()); } Map<String, String> result = ZKUtil.fromStatToMap(stat); result.put("path", path); return JSONRepresentation(result); } private ZooKeeperCommand getZooKeeperCommandIfPresent(String command) { return Enums.getIfPresent(ZooKeeperCommand.class, command).orNull(); } }