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.nifi.atlas.emulator; import kafka.server.KafkaConfig; import kafka.server.KafkaServerStartable; import org.apache.commons.io.FileUtils; import org.apache.zookeeper.server.ServerCnxnFactory; import org.apache.zookeeper.server.ServerConfig; import org.apache.zookeeper.server.ZooKeeperServer; import org.apache.zookeeper.server.persistence.FileTxnSnapLog; import org.apache.zookeeper.server.quorum.QuorumPeerConfig; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.File; import java.io.IOException; import java.net.ServerSocket; import java.util.Properties; /** * Embedded Kafka server, primarily to be used for testing. */ public class EmbeddedKafka { private final KafkaServerStartable kafkaServer; private final Properties zookeeperConfig; private final Properties kafkaConfig; private final ZooKeeperServer zkServer; private final Logger logger = LoggerFactory.getLogger(EmbeddedKafka.class); private final int kafkaPort; private final int zookeeperPort; private boolean started; /** * Will create instance of the embedded Kafka server. Kafka and Zookeeper * configuration properties will be loaded from 'server.properties' and * 'zookeeper.properties' located at the root of the classpath. */ public EmbeddedKafka(boolean useRandomPort) { this(loadPropertiesFromClasspath("/server.properties"), loadPropertiesFromClasspath("/zookeeper.properties"), useRandomPort); } /** * Will create instance of the embedded Kafka server. * * @param kafkaConfig * Kafka configuration properties * @param zookeeperConfig * Zookeeper configuration properties */ public EmbeddedKafka(Properties kafkaConfig, Properties zookeeperConfig, boolean useRandomPort) { this.cleanupKafkaWorkDir(); this.zookeeperConfig = zookeeperConfig; this.kafkaConfig = kafkaConfig; if (useRandomPort) { this.kafkaPort = this.availablePort(); this.zookeeperPort = this.availablePort(); this.kafkaConfig.setProperty("port", String.valueOf(this.kafkaPort)); this.kafkaConfig.setProperty("zookeeper.connect", "localhost:" + this.zookeeperPort); this.zookeeperConfig.setProperty("clientPort", String.valueOf(this.zookeeperPort)); } else { this.kafkaPort = Integer.parseInt(kafkaConfig.getProperty("port")); this.zookeeperPort = Integer.parseInt(zookeeperConfig.getProperty("clientPort")); } this.zkServer = new ZooKeeperServer(); this.kafkaServer = new KafkaServerStartable(new KafkaConfig(kafkaConfig)); } /** * * @return port for Kafka server */ public int getKafkaPort() { if (!this.started) { throw new IllegalStateException("Kafka server is not started. Kafka port can't be determined."); } return this.kafkaPort; } /** * * @return port for Zookeeper server */ public int getZookeeperPort() { if (!this.started) { throw new IllegalStateException("Kafka server is not started. Zookeeper port can't be determined."); } return this.zookeeperPort; } /** * Will start embedded Kafka server. Its data directories will be created * at 'kafka-tmp' directory relative to the working directory of the current * runtime. The data directories will be deleted upon JVM exit. * */ public void start() { if (!this.started) { logger.info("Starting Zookeeper server"); this.startZookeeper(); logger.info("Starting Kafka server"); this.kafkaServer.startup(); logger.info("Embedded Kafka is started at localhost:" + this.kafkaServer.serverConfig().port() + ". Zookeeper connection string: " + this.kafkaConfig.getProperty("zookeeper.connect")); this.started = true; } } /** * Will stop embedded Kafka server, cleaning up all working directories. */ public void stop() { if (this.started) { logger.info("Shutting down Kafka server"); this.kafkaServer.shutdown(); this.kafkaServer.awaitShutdown(); logger.info("Shutting down Zookeeper server"); this.shutdownZookeeper(); logger.info("Embedded Kafka is shut down."); this.cleanupKafkaWorkDir(); this.started = false; } } /** * */ private void cleanupKafkaWorkDir() { File kafkaTmp = new File("target/kafka-tmp"); try { FileUtils.deleteDirectory(kafkaTmp); } catch (Exception e) { logger.warn("Failed to delete " + kafkaTmp.getAbsolutePath()); } } /** * Will start Zookeeper server via {@link ServerCnxnFactory} */ private void startZookeeper() { QuorumPeerConfig quorumConfiguration = new QuorumPeerConfig(); try { quorumConfiguration.parseProperties(this.zookeeperConfig); ServerConfig configuration = new ServerConfig(); configuration.readFrom(quorumConfiguration); FileTxnSnapLog txnLog = new FileTxnSnapLog(new File(configuration.getDataLogDir()), new File(configuration.getDataDir())); zkServer.setTxnLogFactory(txnLog); zkServer.setTickTime(configuration.getTickTime()); zkServer.setMinSessionTimeout(configuration.getMinSessionTimeout()); zkServer.setMaxSessionTimeout(configuration.getMaxSessionTimeout()); ServerCnxnFactory zookeeperConnectionFactory = ServerCnxnFactory.createFactory(); zookeeperConnectionFactory.configure(configuration.getClientPortAddress(), configuration.getMaxClientCnxns()); zookeeperConnectionFactory.startup(zkServer); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } catch (Exception e) { throw new IllegalStateException("Failed to start Zookeeper server", e); } } /** * Will shut down Zookeeper server. */ private void shutdownZookeeper() { zkServer.shutdown(); } /** * Will load {@link Properties} from properties file discovered at the * provided path relative to the root of the classpath. */ private static Properties loadPropertiesFromClasspath(String path) { try { Properties kafkaProperties = new Properties(); kafkaProperties.load(Class.class.getResourceAsStream(path)); return kafkaProperties; } catch (Exception e) { throw new IllegalStateException(e); } } /** * Will determine the available port used by Kafka/Zookeeper servers. */ private int availablePort() { ServerSocket s = null; try { s = new ServerSocket(0); s.setReuseAddress(true); return s.getLocalPort(); } catch (Exception e) { throw new IllegalStateException("Failed to discover available port.", e); } finally { try { s.close(); } catch (IOException e) { // ignore } } } }