Java tutorial
/* * 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. */ package org.apache.hadoop.registry.server.services; import com.google.common.base.Preconditions; import org.apache.commons.lang.StringUtils; import org.apache.curator.ensemble.fixed.FixedEnsembleProvider; import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.FileUtil; import org.apache.hadoop.service.AbstractService; import org.apache.hadoop.registry.client.api.RegistryConstants; import org.apache.hadoop.registry.client.impl.zk.BindingInformation; import org.apache.hadoop.registry.client.impl.zk.RegistryBindingSource; import org.apache.hadoop.registry.client.impl.zk.RegistryInternalConstants; import org.apache.hadoop.registry.client.impl.zk.RegistrySecurity; import org.apache.hadoop.registry.client.impl.zk.ZookeeperConfigOptions; import org.apache.zookeeper.server.ServerCnxnFactory; import org.apache.zookeeper.server.ZooKeeperServer; import org.apache.zookeeper.server.persistence.FileTxnSnapLog; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.File; import java.io.IOException; import java.io.PrintWriter; import java.io.StringWriter; import java.net.InetSocketAddress; import java.net.UnknownHostException; /** * This is a small, localhost Zookeeper service instance that is contained * in a YARN service...it's been derived from Apache Twill. * <p> * It implements {@link RegistryBindingSource} and provides binding information, * <i>once started</i>. Until {@link #start()} is called, the hostname and * port may be undefined. Accordingly, the service raises an exception in this * condition. * <p> * If you wish to chain together a registry service with this one under * the same {@code CompositeService}, this service must be added * as a child first. * <p> * It also sets the configuration parameter * {@link RegistryConstants#KEY_REGISTRY_ZK_QUORUM} * to its connection string. Any code with access to the service configuration * can view it. */ @InterfaceStability.Evolving public class MicroZookeeperService extends AbstractService implements RegistryBindingSource, RegistryConstants, ZookeeperConfigOptions, MicroZookeeperServiceKeys { private static final Logger LOG = LoggerFactory.getLogger(MicroZookeeperService.class); private File instanceDir; private File dataDir; private int tickTime; private int port; private String host; private boolean secureServer; private ServerCnxnFactory factory; private BindingInformation binding; private File confDir; private StringBuilder diagnostics = new StringBuilder(); /** * Create an instance * @param name service name */ public MicroZookeeperService(String name) { super(name); } /** * Get the connection string. * @return the string * @throws IllegalStateException if the connection is not yet valid */ public String getConnectionString() { Preconditions.checkState(factory != null, "service not started"); InetSocketAddress addr = factory.getLocalAddress(); return String.format("%s:%d", addr.getHostName(), addr.getPort()); } /** * Get the connection address * @return the connection as an address * @throws IllegalStateException if the connection is not yet valid */ public InetSocketAddress getConnectionAddress() { Preconditions.checkState(factory != null, "service not started"); return factory.getLocalAddress(); } /** * Create an inet socket addr from the local host + port number * @param port port to use * @return a (hostname, port) pair * @throws UnknownHostException if the server cannot resolve the host */ private InetSocketAddress getAddress(int port) throws UnknownHostException { return new InetSocketAddress(host, port < 0 ? 0 : port); } /** * Initialize the service, including choosing a path for the data * @param conf configuration * @throws Exception */ @Override protected void serviceInit(Configuration conf) throws Exception { port = conf.getInt(KEY_ZKSERVICE_PORT, 0); tickTime = conf.getInt(KEY_ZKSERVICE_TICK_TIME, ZooKeeperServer.DEFAULT_TICK_TIME); String instancedirname = conf.getTrimmed(KEY_ZKSERVICE_DIR, ""); host = conf.getTrimmed(KEY_ZKSERVICE_HOST, DEFAULT_ZKSERVICE_HOST); if (instancedirname.isEmpty()) { File testdir = new File(System.getProperty("test.dir", "target")); instanceDir = new File(testdir, "zookeeper" + getName()); } else { instanceDir = new File(instancedirname); FileUtil.fullyDelete(instanceDir); } LOG.debug("Instance directory is {}", instanceDir); mkdirStrict(instanceDir); dataDir = new File(instanceDir, "data"); confDir = new File(instanceDir, "conf"); mkdirStrict(dataDir); mkdirStrict(confDir); super.serviceInit(conf); } /** * Create a directory, ignoring if the dir is already there, * and failing if a file or something else was at the end of that * path * @param dir dir to guarantee the existence of * @throws IOException IO problems, or path exists but is not a dir */ private void mkdirStrict(File dir) throws IOException { if (!dir.mkdirs()) { if (!dir.isDirectory()) { throw new IOException("Failed to mkdir " + dir); } } } /** * Append a formatted string to the diagnostics. * <p> * A newline is appended afterwards. * @param text text including any format commands * @param args arguments for the forma operation. */ protected void addDiagnostics(String text, Object... args) { diagnostics.append(String.format(text, args)).append('\n'); } /** * Get the diagnostics info * @return the diagnostics string built up */ public String getDiagnostics() { return diagnostics.toString(); } /** * set up security. this must be done prior to creating * the ZK instance, as it sets up JAAS if that has not been done already. * * @return true if the cluster has security enabled. */ public boolean setupSecurity() throws IOException { Configuration conf = getConfig(); String jaasContext = conf.getTrimmed(KEY_REGISTRY_ZKSERVICE_JAAS_CONTEXT); secureServer = StringUtils.isNotEmpty(jaasContext); if (secureServer) { RegistrySecurity.validateContext(jaasContext); RegistrySecurity.bindZKToServerJAASContext(jaasContext); // policy on failed auth System.setProperty(PROP_ZK_ALLOW_FAILED_SASL_CLIENTS, conf.get(KEY_ZKSERVICE_ALLOW_FAILED_SASL_CLIENTS, "true")); //needed so that you can use sasl: strings in the registry System.setProperty(RegistryInternalConstants.ZOOKEEPER_AUTH_PROVIDER + ".1", RegistryInternalConstants.SASLAUTHENTICATION_PROVIDER); String serverContext = System.getProperty(PROP_ZK_SERVER_SASL_CONTEXT); addDiagnostics("Server JAAS context s = %s", serverContext); return true; } else { return false; } } /** * Startup: start ZK. It is only after this that * the binding information is valid. * @throws Exception */ @Override protected void serviceStart() throws Exception { setupSecurity(); ZooKeeperServer zkServer = new ZooKeeperServer(); FileTxnSnapLog ftxn = new FileTxnSnapLog(dataDir, dataDir); zkServer.setTxnLogFactory(ftxn); zkServer.setTickTime(tickTime); LOG.info("Starting Local Zookeeper service"); factory = ServerCnxnFactory.createFactory(); factory.configure(getAddress(port), -1); factory.startup(zkServer); String connectString = getConnectionString(); LOG.info("In memory ZK started at {}\n", connectString); if (LOG.isDebugEnabled()) { StringWriter sw = new StringWriter(); PrintWriter pw = new PrintWriter(sw); zkServer.dumpConf(pw); pw.flush(); LOG.debug(sw.toString()); } binding = new BindingInformation(); binding.ensembleProvider = new FixedEnsembleProvider(connectString); binding.description = getName() + " reachable at \"" + connectString + "\""; addDiagnostics(binding.description); // finally: set the binding information in the config getConfig().set(KEY_REGISTRY_ZK_QUORUM, connectString); } /** * When the service is stopped, it deletes the data directory * and its contents * @throws Exception */ @Override protected void serviceStop() throws Exception { if (factory != null) { factory.shutdown(); factory = null; } if (dataDir != null) { FileUtil.fullyDelete(dataDir); } } @Override public BindingInformation supplyBindingInformation() { Preconditions.checkNotNull(binding, "Service is not started: binding information undefined"); return binding; } }