Kafka app that listens to events from applications and pushes them to a kafka bus
Change-Id: I8026f13f10aa00f6389b89459fa8ebd74de289a3
diff --git a/src/main/java/org/opencord/kafka/impl/KafkaIntegration.java b/src/main/java/org/opencord/kafka/impl/KafkaIntegration.java
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@@ -0,0 +1,216 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed 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.opencord.kafka.impl;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import org.apache.felix.scr.annotations.Activate;
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Deactivate;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+import org.apache.felix.scr.annotations.Service;
+import org.apache.kafka.clients.producer.KafkaProducer;
+import org.apache.kafka.clients.producer.ProducerRecord;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.onosproject.core.ApplicationId;
+import org.onosproject.core.CoreService;
+import org.onosproject.net.config.ConfigFactory;
+import org.onosproject.net.config.NetworkConfigEvent;
+import org.onosproject.net.config.NetworkConfigListener;
+import org.onosproject.net.config.NetworkConfigRegistry;
+import org.onosproject.net.config.basics.SubjectFactories;
+import org.opencord.kafka.EventBusService;
+import org.slf4j.Logger;
+
+import java.util.Properties;
+import java.util.concurrent.ExecutorService;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+import static org.slf4j.LoggerFactory.getLogger;
+
+/**
+ * Sends events to a Kafka event bus.
+ */
+@Service
+@Component(immediate = true)
+public class KafkaIntegration implements EventBusService {
+
+ private final Logger log = getLogger(getClass());
+ private static final Class<KafkaConfig>
+ KAFKA_CONFIG_CLASS = KafkaConfig.class;
+
+ private static final String APP_NAME = "org.opencord.kafka";
+ private ApplicationId appId;
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected CoreService coreService;
+
+ @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+ protected NetworkConfigRegistry configRegistry;
+
+ private static StringSerializer stringSerializer = new StringSerializer();
+
+ private KafkaProducer<String, String> kafkaProducer;
+
+ private InternalNetworkConfigListener configListener =
+ new InternalNetworkConfigListener();
+
+ private final ExecutorService executor = newSingleThreadExecutor(
+ groupedThreads(this.getClass().getSimpleName(), "events", log));
+
+ private ConfigFactory<ApplicationId, KafkaConfig> kafkaConfigFactory =
+ new ConfigFactory<ApplicationId, KafkaConfig>(
+ SubjectFactories.APP_SUBJECT_FACTORY, KAFKA_CONFIG_CLASS,
+ "kafka") {
+ @Override
+ public KafkaConfig createConfig() {
+ return new KafkaConfig();
+ }
+ };
+
+ private static final String BOOTSTRAP_SERVERS = "bootstrap.servers";
+ private static final String RETRIES = "retries";
+ private static final String RECONNECT_BACKOFF = "reconnect.backoff.ms";
+ private static final String INFLIGHT_REQUESTS =
+ "max.in.flight.requests.per.connection";
+ private static final String ACKS = "acks";
+ private static final String KEY_SERIALIZER = "key.serializer";
+ private static final String VALUE_SERIALIZER = "value.serializer";
+ private static final String STRING_SERIALIZER =
+ stringSerializer.getClass().getCanonicalName();
+
+ private static final String TIMESTAMP = "timestamp";
+
+ @Activate
+ public void activate() {
+ appId = coreService.registerApplication(APP_NAME);
+ configRegistry.registerConfigFactory(kafkaConfigFactory);
+ configRegistry.addListener(configListener);
+
+ configure();
+
+ log.info("Started");
+ }
+
+ @Deactivate
+ public void deactivate() {
+ configRegistry.removeListener(configListener);
+ configRegistry.unregisterConfigFactory(kafkaConfigFactory);
+
+ executor.shutdownNow();
+
+ shutdownKafka();
+ log.info("Stopped");
+ }
+
+ private void configure() {
+ KafkaConfig config =
+ configRegistry.getConfig(appId, KAFKA_CONFIG_CLASS);
+ if (config == null) {
+ log.info("Kafka configuration not present");
+ return;
+ }
+ configure(config);
+ }
+
+ private void configure(KafkaConfig config) {
+ checkNotNull(config);
+
+ Properties properties = new Properties();
+ properties.put(BOOTSTRAP_SERVERS, config.getBootstrapServers());
+ properties.put(RETRIES, config.getRetries());
+ properties.put(RECONNECT_BACKOFF, config.getReconnectBackoff());
+ properties.put(INFLIGHT_REQUESTS, config.getInflightRequests());
+ properties.put(ACKS, config.getAcks());
+ properties.put(KEY_SERIALIZER, STRING_SERIALIZER);
+ properties.put(VALUE_SERIALIZER, STRING_SERIALIZER);
+
+ startKafka(properties);
+ }
+
+ private void unconfigure() {
+ shutdownKafka();
+ }
+
+ private void startKafka(Properties properties) {
+ shutdownKafka();
+
+ // Kafka client doesn't play nice with the default OSGi classloader
+ // This workaround temporarily changes the thread's classloader so that
+ // the Kafka client can load the serializer classes.
+ ClassLoader original = Thread.currentThread().getContextClassLoader();
+ Thread.currentThread().setContextClassLoader(this.getClass().getClassLoader());
+ try {
+ kafkaProducer = new KafkaProducer<>(properties);
+ } finally {
+ Thread.currentThread().setContextClassLoader(original);
+ }
+ }
+
+ private void shutdownKafka() {
+ if (kafkaProducer != null) {
+ kafkaProducer.close();
+ kafkaProducer = null;
+ }
+ }
+
+ private void logException(Exception e) {
+ if (e != null) {
+ log.error("Exception while sending to Kafka", e);
+ }
+ }
+
+ @Override
+ public void send(String topic, JsonNode data) {
+ if (kafkaProducer == null) {
+ return;
+ }
+
+ if (log.isTraceEnabled()) {
+ log.trace("Sending event to Kafka: {}", data.toString());
+ }
+
+ kafkaProducer.send(new ProducerRecord<>(topic, data.toString()),
+ (r, e) -> logException(e));
+ }
+
+ private class InternalNetworkConfigListener implements NetworkConfigListener {
+
+ @Override
+ public void event(NetworkConfigEvent event) {
+ switch (event.type()) {
+ case CONFIG_ADDED:
+ case CONFIG_UPDATED:
+ configure((KafkaConfig) event.config().get());
+ break;
+ case CONFIG_REMOVED:
+ unconfigure();
+ break;
+ case CONFIG_REGISTERED:
+ case CONFIG_UNREGISTERED:
+ default:
+ break;
+ }
+ }
+
+ @Override
+ public boolean isRelevant(NetworkConfigEvent event) {
+ return event.configClass().equals(KAFKA_CONFIG_CLASS);
+ }
+ }
+}