Docker：如何连接到 docker-compose.yml 文件中未定义的 kafka 容器

Question

I have 3 docker-compose files. One to start the kafka and the other two are consumer and producer. Added external_links in the other docker-compose files to kafka, but still unable to access kafka from inside containers. From outside the container, I can access through localhost:9092, but what about inside docker container.

# docker-compose1.yml
version: "3.6"
services:
  zookeeper:
    image: 'docker.io/bitnami/zookeeper:3.7'
    container_name: zookeeper
    ports:
      - '2181:2181'
    volumes:
      - 'zookeeper_data:/bitnami'
    environment:
      - ALLOW_ANONYMOUS_LOGIN=yes

  kafka:
    image: 'docker.io/bitnami/kafka:3'
    container_name: kafka
    ports:
      - '9092:9092'
    volumes:
      - 'kafka_data:/bitnami'
    environment:
      - KAFKA_CFG_ZOOKEEPER_CONNECT=zookeeper:2181
      - KAFKA_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_ADVERTISED_LISTENERS=PLAINTEXT://kafka:29092,PLAINTEXT_HOST://localhost:9092
      - ALLOW_PLAINTEXT_LISTENER=yes
      - KAFKA_ADVERTISED_HOST_NAME=localhost
      - KAFKA_ADVERTISED_PORT=9092
      - KAFKA_AUTO_CREATE_TOPICS_ENABLE=true
    depends_on:
      - zookeeper


volumes:
  zookeeper_data:
    external: true
  kafka_data:
    external: true

# docker-compose2.yml
version: "3.6"
services:
  web:
    hostname: ocp-transmitter
    image: 'ocp/transmitter'
    command: bash -c "bundle install && foreman start"
    ports:
      - '3000:3000'
    volumes:
      - .:/app:cached
    stdin_open: true
    tty: true
    external_links:
      - kafka

Answer 1

First, remove these, they are deprecated

  - KAFKA_ADVERTISED_HOST_NAME=localhost
  - KAFKA_ADVERTISED_PORT=9092

Second, read the bitnami image documentation more carefully, all the Kafka properties start with KAFKA_CFG_ , then read the section about internal/external listeners

The linked answer(s) are correct Communication between multiple docker-compose projects

Run docker.network create with a name to setup an external bridge.network separately from Compose, then add networks section to each service in that.network (Zookeeper, Kafka, and your Kafka clients). Then make sure it's external

networks:
  example-net:
    external: true

Then you'd use kafka:29092 in your apps, not localhost, and not port 9092