Apache Kafka Consumer Backends

Prior to version 0.11, the Kafka payload did not include a location to store correlation data, so end-to-end Business Transaction correlation is only possible with Kafka client and broker versions 0.11 or greater.

KafkaConsumer.poll and Kafka Stream Entry Points

To instrument Kafka consumer entry points using KafkaConsumer.poll() or Kafka Streams, identify the method where the consumer reads messages in a loop in a custom interceptor definition. We instrument the iterator's next method to start and end the BT for each message. There could be many iterators used for iterating messages but we only support iterators that are of type:

• kafka.consumer.ConsumerIterator
• org.apache.kafka.clients.consumer.ConsumerRecords$ConcatenatedIterable$1

1. Identify the class and method of the loop that processes messages from Kafka. Consider for example a class MyConsumer that employs the following loop to poll and process messages from Kafka:

   private void pollMessages() throws Exception {
      ConsumerRecords<String, String> records = kafkaConsumer.poll(1000);
      for (ConsumerRecord<String, String> record : records) {
         //Processing of the records
         System.out.println(record.value());
      }
   }

   For this case, you want to intercept:

   • Class: MyConsumer
   • Method: pollMessages
2. Use your preferred text editor to create and edit a file named custom-interceptors.xml at the following path:
   <agent_home>/<version_number>/conf 
   
   For example:
   /usr/home/appdynamics/appagent/ver4.3.1.0/conf/custom-interceptors.xml

3. Copy the following XML to custom-interceptors.xml:

   <custom-interceptors>
       <custom-interceptor>
           <interceptor-class-
   name>com.singularity.KafkaMarkerMethodInterceptor</interceptor-class-name>
           <match-class type="matches-class">
               <name filter-type="equals">my-fully-qualified-class-name</name>
           </match-class>
           <match-method>
               <name>my-method-name</name>
           </match-method>
       </custom-interceptor>
   </custom-interceptors>

4. Set the value of the class name to the name of your consumer class. For instance, to specify the MyConsumer class:

   <match-class type="matches-class">
       <name filter-type="equals">com.mycompany.mypackage.MyConsumer</name>
   </match-class>

5. Set the value of the method name to the name of your message processing loop method. For instance, to specify the pollMessages method:

   <match-method>
       <name>pollMessages</name>
   </match-method>

   
   After the Java Agent reads the updated configuration, it detects consumer activity and upstream Kafka queue. The application flow map shows the tier receiving data from the Kafka queue. The Kafka queue does not appear on the BT level flow map.

Kafka SimpleConsumer Entry Points

To enable consumer entry points for Kafka clients that retrieve messages using SimpleConsumer.fetch(), register the enable-kafka-consumer node property with a value of "true".