[jira] [Created] (KAFKA-16708) Allow dynamic port for advertised listeners in Docker image

["Chris Bono (Jira)" <ji...@apache.org>]

Chris Bono created KAFKA-16708:
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             Summary: Allow dynamic port for advertised listeners in Docker image
                 Key: KAFKA-16708
                 URL: https://issues.apache.org/jira/browse/KAFKA-16708
             Project: Kafka
          Issue Type: Improvement
            Reporter: Chris Bono


First of all, thank you all for adding the official Kafka Docker image (I know it is a big responsibility and adds to the team workload).

I am migrating from {{wurstmeister/kafka}} to the official {{apache/kafka}} image. 

My advertised port is not static and was relying on [the PORT_COMMAND feature|https://github.com/wurstmeister/kafka-docker/commit/c66375fc3b94e98dbecd603c5d2b44c06e927e88] in the {{wurstmeister/kafka}} image to determine the port programatically. 

This would let me define a docker-compose as follows:

{{}}

 
{code:java}
services:
  kafka:
    image: apache/kafka:latest
    hostname: kafka
    ports:
      - "9092"
    volumes:
      - '/var/run/docker.sock.raw:/var/run/docker.sock'
    environment:
      KAFKA_NODE_ID: 1
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: 'CONTROLLER:PLAINTEXT,PLAINTEXT_DOCKER:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT'
      KAFKA_LISTENERS: 'CONTROLLER://kafka:29093,PLAINTEXT_DOCKER://kafka:29092,PLAINTEXT_HOST://0.0.0.0:9092'
      KAFKA_ADVERTISED_LISTENERS: 'PLAINTEXT_DOCKER://kafka:29092,PLAINTEXT_HOST://localhost:_{PORT_COMMAND}'
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_PROCESS_ROLES: 'broker,controller'
      KAFKA_CONTROLLER_QUORUM_VOTERS: '1@kafka:29093'
      KAFKA_INTER_BROKER_LISTENER_NAME: 'PLAINTEXT_DOCKER'
      KAFKA_CONTROLLER_LISTENER_NAMES: 'CONTROLLER'
      PORT_COMMAND: "docker ps | egrep 'kafka' | cut -d: -f 3 | cut -d- -f 1"{code}
 

{{}}

Notice how the "ports" are dynamically mapped (i.e. not *"port:port"* syntax) - the actual port will *not* be "9092".


Do you have a suggestion for an alternative approach on how to obtain a non-static port for advertised listeners? If not, would adding conditional support for this feature be welcomed? 


I am aware of the complication/concern of this request as it is Docker in Docker for non-root users (described [here|https://jonfriesen.ca/articles/docker-in-docker-non-root-user/]) and as such we could make it inactive by default and users would have to opt-in explicitly.

I have created a [rough WIP|https://github.com/onobc/kafka/commit/6556c4adbf08155b89c9804c2c5d1a988f8371f2] that illustrates the concept (there is no conditionality in it currently). 

Note that the container is not run as {*}root{*}, but rather the *appuser* is added to whatever group that own the docker.sock (which on my machine is root).

 

P.S. This is my first time filing an issue w/ Kafka so if I missed anything please let me know and I am glad to add whatever other info, etc.. 



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