Idea运行Kafka.scala踩坑

未指定 server.properties

直接运行时，报错信息如下：

> Task :core:Kafka.main() FAILED
USAGE: java [options] KafkaServer server.properties [--override property=value]*
Option               Description                                         
------               -----------                                         
--override <String>  Optional property that should override values set in
                       server.properties file        

解决方案：Run -> Edit Configurations... ，打开如下图所示对话框，在 Program Arguments 一栏填入 configserver.properties

未打印运行日志

Kafka程序确实启动了，但是不知道什么地方出错了？

> Task :core:Kafka.main()
log4j:WARN No appenders could be found for logger (kafka.server.KafkaConfig).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

> Task :core:Kafka.main() FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':core:Kafka.main()'.
> Process 'command 'D:/Common/Java/jdk1.8.0_131/bin/java.exe'' finished with non-zero exit value 1

将 config 目录下的 log4j.properties 文件复制到 core/src/main/resources 目录下，这样可以让 Kafka 在运行时能够输出日志信息：

Connection refused

现在运行时能看到日志了：

[2021-09-07 09:52:16,487] INFO Opening socket connection to server 127.0.0.1/127.0.0.1:2181. Will not attempt to authenticate using SASL (unknown error) (org.apache.zookeeper.ClientCnxn)
[2021-09-07 09:52:17,503] WARN Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused: no further information
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
	at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
	at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1141)
[2021-09-07 09:52:17,613] INFO Opening socket connection to server 0:0:0:0:0:0:0:1/0:0:0:0:0:0:0:1:2181. Will not attempt to authenticate using SASL (unknown error) (org.apache.zookeeper.ClientCnxn)
[2021-09-07 09:52:18,630] WARN Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused: no further information
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
	at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:361)
	at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1141)

2181 是 ZooKeeper 的端口，我们知道 Kafka 是需要用到 ZooKeeper 的，所以我们需要先安装和启动 ZooKeeper。

因为我当前的 Kafka 版本是 1.0.0，我们看到它依赖的 zookeeper 是 3.4.10，所以我决定搭建 ZooKeeper 服务时也用 3.4.10 版本：

个人比较喜欢用Docker来本地测试：Docker安装zookeeper