Port Binding Error When Connecting to Localhost Kafka Broker from Localhost Consumer in Docker Container
I Have a Zookeeper Running on Port 2181 (Default) and a Kafka Server Listening on Port 9090 on My Local Machine. When I Run Kafka Cli Locally, or...
I have a Zookeeper running on port 2181 (default) and a Kafka server listening on port 9090 on my local machine.
When I run kafka CLI locally, or consumer/producer apps locally, I have no problem connecting.
I then try to bundle a Kafka consumer into a Docker container, and run that Docker container locally, e.g.:
docker run -p 9092:9092 --rm <DOCKER_IMAGE>
This gives the error:
(Error starting userland proxy: Bind for 0.0.0.0:9090 failed: port is already allocated.)
This makes sense since Kafka Server is bound to 9092, as shown in nmap -p 9092 localhost:
PORT STATE SERVICE
9092/tcp open XmlIpcRegSvc
I'd have no problem mapping the Docker container to a different port via -p XXX:9090, but how do I get the local Kafka server to listen on that new port without binding to it?
1 Answer
So after some digging I found a few options. (Note: I'm on a mac so #2 may not be applicable to everyone).
- Include
--network=hostin thedocker runcommand (as seen here). - Don't change the
docker runcommand at all, and instead connect to broker athost.docker.internal:9092inside the container consumer/publisher code. As seen here.
I wasn't able to get #1 to work out for me (I'm sure it's user error). However #2 worked perfectly and just required a config change inside the container.
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
