一、概述

# The address the socket server listens on. It will get the value returned from
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092

# Hostname and port the broker will advertise to producers and consumers. If not set,
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#advertised.listeners=PLAINTEXT://your.host.name:9092

listeners就是主要用来定义Kafka Broker的Listener的配置项。
advertised.listeners参数的作用就是将Broker的Listener信息发布到Zookeeper中

二、试验

1、默认都不配置

zookeeper查看kafka地址
get /brokers/ids/0
"endpoint":["PLAINTEXT://k8s01:9002"]

kafka创建topic
bin/kafka-topics.sh --create --bootstrap-server localhost:9002 --replication-factor 1 --partitions 1 --topic test
bin/kafka-topics.sh --list --bootstrap-server localhost:9002
如果使用
bin/kafka-topics.sh --list --bootstrap-server 192.168.10.131:9002
需要提前添加主机hosts
192.168.10.131 k8s01

2、两者都设置为同一IP和端口

配置 
listeners=PLAINTEXT://192.168.10.131:9092
advertised.listeners=PLAINTEXT://192.168.10.131:9092

zookeeper查看kafka地址
get /brokers/ids/0
"endpoint":["PLAINTEXT://192.168.10.131:9092"]

bin/kafka-topics.sh --list --bootstrap-server 192.168.10.131:9092

3、advertised改为随机主机名

配置 
listeners=PLAINTEXT://192.168.10.131:9092
advertised.listeners=PLAINTEXT://test-kafka:9092

zookeeper查看kafka地址
get /brokers/ids/0
"endpoint":["PLAINTEXT://test-kafka:9092"]

4、listeners为127.0.0.1

配置 
listeners=PLAINTEXT://127.0.0.1:9092
advertised.listeners=PLAINTEXT://192.168.10.131:9092

zookeeper查看kafka地址
get /brokers/ids/0
"endpoint":["PLAINTEXT://192.168.10.131:9092"]

5、内外网分流

listener.security.protocol.map=EXTERNAL:PLAINTEXT,INTERNAL:PLAINTEXT
listeners=EXTERNAL://192.168.10.131:9092,INTERNAL://192.168.10.131:9093
inter.broker.listener.name=INTERNAL

zookeeper查看kafka地址
get /brokers/ids/0
"endpoints":["EXTERNAL://192.168.10.131:9092","INTERNAL://192.168.10.131:9093"]
内网访问可以使用：192.168.10.131:9093
外网访问使用：192.168.10.131:9092
这在kafka部署到kubernetes时候就很有用了

6、总结

listeners就是主要用来定义Kafka Broker的Listener的配置项。
advertised.listeners参数的作用就是将Broker的Listener信息发布到Zookeeper中
inter.broker.listener.name：专门用于Kafka集群中Broker之间的通信
listener.security.protocol.map
配置监听者的安全协议的，比如PLAINTEXT、SSL、SASL_PLAINTEXT、SASL_SSL

listeners
是kafka真正bind的地址
advertised.listeners
是暴露给外部的listeners，如果没有设置，会用listeners