Can I get producer client id in kafka consumer?

Question

During creating kafka producer, we can assign a client id. What is it used for? Can I get the producer client id in a consumer? For example, to see which producer produced the message?

Answer 1

No, a consumer cannot get the producer's client-id.

From the Kaka documentation, client-ids are:

An id string to pass to the server when making requests. The purpose of this is to be able to track the source of requests beyond just ip/port by allowing a logical application name to be included in server-side request logging.

They are only used for identifying clients in the broker logs.

Answer 2

No, you'd have to pass it on as part of the key or value if you need it at the consumer side.

Kafka's philosophy is to decouple producers and consumers. A topic can be read by 0-n consumers and be written to by 0-n producers. Kafka is usually used for communication between (micro)service boundaries where services don't care about who produced a message, just about its contents.