[CAMEL-15022] Opentracing doesn't work with Kafka Component

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.23.4
• Fix Version/s: 2.25.2, 3.4.2, 3.5.0
• Component/s: camel-opentracing
• Estimated Complexity: Unknown
• Assignee: Andrea Cosentino
• Reporter: Gerald Nunn
• Created: 06/May/20 17:44
• Updated: 13/Jul/20 10:19
• Resolved: 13/Jul/20 10:19

Description

In Kafka the headers are stored as byte arrays rather then string. OpenTracing with Jaeger inserts a string header uber-trace-id which works. However when it tries to read it as a string when the message is consumed it presumably does a toString which doesn't return the actual string since the header is returned as a byte array.

This can be worked around by using a KafkaHeaderDeserializer as per here:

https://github.com/gnunn1/seating/blob/master/seat-listener/src/main/java/com/redhat/demo/HeaderDeserializer.java

Note you need to deserialize the kafka.TOPIC as well since the KafkaSpanDecorator tries to cast the header as a string which fails the header is returned as byte array.

https://github.com/apache/camel/blob/camel-2.23.x/components/camel-opentracing/src/main/java/org/apache/camel/opentracing/decorators/KafkaSpanDecorator.java#L49

 

Issue Links

• links to: GitHub Pull Request #3994