content: /*
   * 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.cloudstack.mom.kafka;
  
  import java.io.FileInputStream;
  
  import java.util.Map;
  import java.util.UUID;
  import java.util.Properties;
  
  import javax.naming.ConfigurationException;
  
  
  import org.apache.cloudstack.framework.events.Event;
  import org.apache.cloudstack.framework.events.EventBus;
  import org.apache.cloudstack.framework.events.EventBusException;
  import org.apache.cloudstack.framework.events.EventSubscriber;
  import org.apache.cloudstack.framework.events.EventTopic;
  
  import com.cloud.utils.component.ManagerBase;
  
  import org.apache.kafka.clients.producer.Producer;
  import org.apache.kafka.clients.producer.KafkaProducer;
  import org.apache.kafka.clients.producer.ProducerRecord;
  
  import com.cloud.utils.PropertiesUtil;
  
  public class KafkaEventBus extends ManagerBase implements EventBus {
  
      public static final String DEFAULT_TOPIC = "cloudstack";
      public static final String DEFAULT_SERIALIZER = "org.apache.kafka.common.serialization.StringSerializer";
  
      private String _topic = null;
      private Producer<String,String> _producer;
  
      @Override
      public boolean configure(String name, Map<String, Object> params) throws ConfigurationException {
  
          final Properties props = new Properties();
  
          try (final FileInputStream is = new FileInputStream(PropertiesUtil.findConfigFile("kafka.producer.properties"));) {
              props.load(is);
  
              _topic = (String)props.remove("topic");
              if (_topic == null) {
                  _topic = DEFAULT_TOPIC;
              }
  
              if (!props.containsKey("key.serializer")) {
                  props.put("key.serializer", DEFAULT_SERIALIZER);
              }
  
              if (!props.containsKey("value.serializer")) {
                  props.put("value.serializer", DEFAULT_SERIALIZER);
              }
          } catch (Exception e) {
              throw new ConfigurationException("Could not read kafka properties");
          }
  
          _producer = new KafkaProducer<String,String>(props);
          _name = name;
  
          return true;
      }
  
      @Override
      public void setName(String name) {
          _name = name;
      }
  
      @Override
      public UUID subscribe(EventTopic topic, EventSubscriber subscriber) throws EventBusException {
          logger.debug("subscribing '{}' to events of type '{}' from '{}'", subscriber.toString(), topic.getEventType(), topic.getEventSource());
  
          /* NOOP */
          return UUID.randomUUID();
      }
  
      @Override
      public void unsubscribe(UUID subscriberId, EventSubscriber subscriber) throws EventBusException {
          logger.debug("unsubscribing '{}'", subscriberId);
          /* NOOP */
      }
  
      @Override
      public void publish(Event event) throws EventBusException {
          logger.trace("publish '{}'", event.getDescription());
          ProducerRecord<String, String> newRecord = new ProducerRecord<>(_topic, event.getResourceUUID(), event.getDescription());
          _producer.send(newRecord);
      }
  
      @Override
      public String getName() {
          return _name;
      }
  
      @Override
      public boolean start() {
          return true;
      }
  
      @Override
      public boolean stop() {
          return true;
      }
  }
  