Want to deploy my application on multi-node kafka cluster, but not able to connect docker conatainers internally

Question

---
version: '2'
services:
  zookeeper-1:
    image: confluentinc/cp-zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 1
      ZOOKEEPER_CLIENT_PORT: 22181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888
    network_mode: host
    extra_hosts:
      - "moby:127.0.0.1"

  zookeeper-2:
    image: confluentinc/cp-zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 2
      ZOOKEEPER_CLIENT_PORT: 32181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888
    network_mode: host
    extra_hosts:
      - "moby:127.0.0.1"

  zookeeper-3:
    image: confluentinc/cp-zookeeper:latest
    environment:
      ZOOKEEPER_SERVER_ID: 3
      ZOOKEEPER_CLIENT_PORT: 42181
      ZOOKEEPER_TICK_TIME: 2000
      ZOOKEEPER_INIT_LIMIT: 5
      ZOOKEEPER_SYNC_LIMIT: 2
      ZOOKEEPER_SERVERS: localhost:22888:23888;localhost:32888:33888;localhost:42888:43888
    network_mode: host
    extra_hosts:
      - "moby:127.0.0.1"

  kafka-1:
    image: confluentinc/cp-kafka:latest
    network_mode: host
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:19092
    extra_hosts:
      - "moby:127.0.0.1"

  kafka-2:
    image: confluentinc/cp-kafka:latest
    network_mode: host
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3
    environment:
      KAFKA_BROKER_ID: 2
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:29092
    extra_hosts:
      - "moby:127.0.0.1"

  kafka-3:
    image: confluentinc/cp-kafka:latest
    network_mode: host
    depends_on:
      - zookeeper-1
      - zookeeper-2
      - zookeeper-3
    environment:
      KAFKA_BROKER_ID: 3
      KAFKA_ZOOKEEPER_CONNECT: localhost:22181,localhost:32181,localhost:42181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://localhost:39092
    extra_hosts:
      - "moby:127.0.0.1"

this is the example from confluence for multi-node cluster, used network mode=host. what address should i use for internal connection.

for example the below one is single-node kafka cluster

kafka:
image: confluentinc/cp-kafka:latest
    depends_on:
      - zookeeper
    ports:
      - 9092:9092
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:29092,PLAINTEXT_HOST://localhost:9092
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
      KAFKA_INTER_BROKER_LISTENER_NAME: PLAINTEXT
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1

here I can use kafka:29092 for internal connection.

i followed same approach for multi-node but getting error. can anyone explain why this approach not work for multi-node cluster and how to establish internal connection. thank you.

Answer 1

here I can use kafka:29092 for internal connection

That's because it was listed as an advertised listener for internal clients to connect to. KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:29092

You've removed the service name from each of your brokers, so clients are now trying to connect to just the advertised localhost addresses and failing because the containers running your applications are therefore trying to connect to themselves (via localhost), not any of the kafka containers.