Add Kafka as an event source

contribs/build.gradle

@@ -17,7 +17,7 @@ dependencies {
 	compileOnly "javax.ws.rs:jsr311-api:${revJsr311Api}"
 	compile "io.swagger:swagger-jaxrs:${revSwagger}"
 
-	compile "org.apache.kafka:kafka-clients:2.2.0"
+	compile "org.apache.kafka:kafka-clients:${revKafkaClient}"
 	testCompile "org.eclipse.jetty:jetty-server:${revJetteyServer}"
 	testCompile "org.eclipse.jetty:jetty-servlet:${revJettyServlet}"
 	testCompile "org.slf4j:slf4j-log4j12:${revSlf4jlog4j}"

contribs/src/main/java/com/netflix/conductor/contribs/KafkaModule.java

@@ -0,0 +1,46 @@
+/**
+ * Copyright 2016 Netflix, Inc.
+ *
+ * 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 com.netflix.conductor.contribs;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import com.google.inject.AbstractModule;
+import com.google.inject.Singleton;
+import com.google.inject.multibindings.ProvidesIntoMap;
+import com.google.inject.multibindings.StringMapKey;
+import com.google.inject.name.Named;
+import com.netflix.conductor.core.config.Configuration;
+import com.netflix.conductor.core.events.EventQueueProvider;
+import com.netflix.conductor.core.events.kafka.KafkaEventQueueProvider;
+
+/**
+ * @author preeth, rickfish
+ *
+ */
+public class KafkaModule extends AbstractModule {
+  private static Logger logger = LoggerFactory.getLogger(KafkaModule.class);
+
+  @Override
+  protected void configure() {
+    logger.info("Kafka module configured.");
+  }
+
+  @ProvidesIntoMap
+  @StringMapKey("kafka")
+  @Singleton
+  @Named("EventQueueProviders")
+  public EventQueueProvider getKafkaEventQueueProvider(Configuration configuration) {
+    return new KafkaEventQueueProvider(configuration);
+  }
+}

contribs/src/main/java/com/netflix/conductor/contribs/kafka/KafkaLoginModule.java

@@ -0,0 +1,131 @@
+package com.netflix.conductor.contribs.kafka;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+
+import javax.security.auth.Subject;
+import javax.security.auth.callback.CallbackHandler;
+import javax.security.auth.login.LoginException;
+import javax.security.auth.spi.LoginModule;
+
+import org.apache.commons.lang3.StringUtils;
+
+/**
+ * Java security module used to provide JAAS username and password for access to a Kafka topic
+ * @author rickfish
+ *
+ */
+public class KafkaLoginModule implements LoginModule {
+
+    String KAFKA_EVENTS_JAAS_USERNAME_PROPERTY_NAME = "kafka.events.jaas.username";
+    String KAFKA_DEFAULT_JAAS_USERNAME_PROPERTY_NAME = "kafka.default.jaas.username";
+    String KAFKA_DEFAULT_JAAS_USERNAME_DEFAULT_VALUE = "";
+
+    String KAFKA_EVENTS_JAAS_PASSWORD_PROPERTY_NAME = "kafka.events.jaas.password";
+    String KAFKA_DEFAULT_JAAS_PASSWORD_PROPERTY_NAME = "kafka.default.jaas.password";
+    String KAFKA_DEFAULT_JAAS_PASSWORD_DEFAULT_VALUE = "";
+
+	public KafkaLoginModule() {
+		super();
+	}
+	protected Map<String, Object> sharedState;
+	protected Map<String, Object> options;
+	@SuppressWarnings("unchecked")
+	@Override
+	public void initialize(Subject subject, CallbackHandler callbackHandler, Map<String, ?> sharedState, Map<String, ?> options) {
+		this.sharedState = (Map<String, Object>) sharedState;
+		this.options = (Map<String, Object>) options;
+	}
+
+	@Override
+	public boolean login() throws LoginException {
+		String userName = getProperty(getKafkaEventsJaasUsername(), null);
+		String password = getProperty(getKafkaEventsJaasPassword(), null);		
+		List<String> messages = new ArrayList<String>();
+
+		if (StringUtils.isBlank(userName)) {
+			messages.add("The user name is required.");
+		}
+
+		if (StringUtils.isBlank(password)) {
+			messages.add("The password is required.");
+		}
+
+		if (messages.size() > 0) {
+			throw new LoginException(String.join(" ", messages));
+		}
+
+		sharedState.put("javax.security.auth.login.name", userName);
+		sharedState.put("javax.security.auth.login.password", password.toCharArray());
+
+		return true;
+	}
+
+	@Override
+	public boolean logout() throws LoginException {
+		return true;
+	}
+
+	@Override
+	public boolean abort() throws LoginException {
+		return true;
+	}
+
+	@Override
+	public boolean commit() throws LoginException {
+		return true;
+	}
+
+
+    /**
+     * Get the JAAS username for the 'events' topic
+     * @return
+     */
+    String getKafkaDefaultJaasUsername() {
+        return getProperty(KAFKA_EVENTS_JAAS_USERNAME_PROPERTY_NAME,
+       		KAFKA_DEFAULT_JAAS_USERNAME_DEFAULT_VALUE);
+    }
+
+    /**
+     * Get the JAAS username for the 'events' topic
+     * @return
+     */
+    String getKafkaEventsJaasUsername() {
+        return getProperty(KAFKA_EVENTS_JAAS_USERNAME_PROPERTY_NAME,
+            getKafkaDefaultJaasUsername());
+    }
+
+    /**
+     * There are several uses for Kafka topics. If all the topics are in the same Kafka cluster, this property can be used.
+     * Otherwise, the JAAS password for each specific use should be used.
+     */
+    String getKafkaDefaultJaasPassword() {
+        return getProperty(KAFKA_DEFAULT_JAAS_PASSWORD_PROPERTY_NAME,
+            KAFKA_DEFAULT_JAAS_PASSWORD_DEFAULT_VALUE);
+    }
+
+    /**
+     * Get the JAAS password for the 'events' topic
+     * @return
+     */
+    String getKafkaEventsJaasPassword() {
+        return getProperty(KAFKA_EVENTS_JAAS_PASSWORD_PROPERTY_NAME,
+            getKafkaDefaultJaasPassword());
+    }
+
+    public String getProperty(String key, String defaultValue) {
+
+		String val = null;
+		try{
+			val = System.getenv(key.replace('.','_'));
+			if (val == null || val.isEmpty()) {
+				val = Optional.ofNullable(System.getProperty(key)).orElse(defaultValue);
+			}
+		}catch(Exception e){
+			e.printStackTrace();
+		}
+		return val;
+	}
+}