Kafka Docker配置报错：未为监听器PLAINTEXT定义安全协议

问题原因 #

错误提示No security protocol defined for listener PLAINTEXT的核心原因是：你在KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP中定义的监听器名称是CLIENT和EXTERNAL，但在KAFKA_CFG_LISTENERS和KAFKA_CFG_ADVERTISED_LISTENERS中却使用了PLAINTEXT作为监听器名称，两者不匹配，导致Kafka无法找到对应监听器的安全协议配置。

修复后的docker-compose配置 #

version: "3.9"

services:
  zookeeper:
    image: 'bitnami/zookeeper:latest'
    ports:
      - '2181:2181'
    environment:
      - ALLOW_ANONYMOUS_LOGIN=yes
  kafka:
    image: 'bitnami/kafka:latest'
    ports:
      - '9092:9092'
      - '9093:9093'
    environment:
      - KAFKA_BROKER_ID=1
      - KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP=CLIENT:PLAINTEXT,EXTERNAL:PLAINTEXT
      - KAFKA_CFG_LISTENERS=CLIENT://:9092,EXTERNAL://:9093
      - KAFKA_CFG_ADVERTISED_LISTENERS=CLIENT://127.0.0.1:9092,EXTERNAL://localhost:9093
      - KAFKA_CFG_ZOOKEEPER_CONNECT=zookeeper:2181
      - ALLOW_PLAINTEXT_LISTENER=yes
      - KAFKA_CFG_INTER_BROKER_LISTENER_NAME=CLIENT
      - KAFKA_ZOOKEEPER_PROTOCOL=PLAINTEXT
    depends_on:
      - zookeeper

关键修改点 #

• 将KAFKA_CFG_LISTENERS中的PLAINTEXT://:9092改为CLIENT://:9092，与KAFKA_CFG_LISTENER_SECURITY_PROTOCOL_MAP中定义的监听器名称保持一致
• 将KAFKA_CFG_ADVERTISED_LISTENERS中的PLAINTEXT://127.0.0.1:9092改为CLIENT://127.0.0.1:9092，确保对外声明的监听器名称与映射配置匹配

这样修改后，Kafka就能正确识别每个监听器对应的安全协议，启动时不会再出现该错误。

内容的提问来源于stack exchange，提问作者user4981459