Kafka技术详解[4]:构建简易Windows环境下的Kafka集群

目录

Kafka基础

集群部署

解压文件

安装ZooKeeper

安装Kafka

封装启动脚本

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Kafka基础

Kafka虽然借鉴了JMS规范的思想，但在设计原理上并未完全遵循JMS规范。因此，Kafka内部包含了许多用于数据传输的组件对象，这些组件相互关联，共同实现了高效的数据传输。下面，我们将详细介绍Kafka中的基础概念及核心组件，并展示如何在Windows环境下搭建一个简单的Kafka集群以供学习和练习之用。

集群部署

尽管生产环境中通常使用Linux系统搭建服务器集群，但为了便于理解和实践，我们将在此章节中搭建一个基于Windows系统的简易集群。关于Linux集群的搭建将在后续章节中详述。

解压文件

1. 在磁盘根目录创建文件夹cluster，文件夹名称应保持简短。
2. 将Kafka安装包kafka_2.12-3.6.1.tgz解压缩至cluster文件夹下的kafka子文件夹中。

安装ZooKeeper

1. 将解压缩后的文件夹重命名为kafka-zookeeper。

2. 修改config/zookeeper.properties文件：

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   The ASF licenses this file to You under the Apache License, Version 2.0

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   the directory where the snapshot is stored.

   此处注意，如果文件目录不存在，会自动创建

   dataDir=E:/cluster/kafka-zookeeper/data

   the port at which the clients will connect

   ZooKeeper默认端口为2181

   clientPort=2181

   disable the per-ip limit on the number of connections since this is a non-production config

   maxClientCnxns=0

   Disable the adminserver by default to avoid port conflicts.

   Set the port to something non-conflicting if choosing to enable this

   admin.enableServer=false

   admin.serverPort=8080

安装Kafka

1. 将解压缩后的kafka-zookeeper文件夹复制一份，并重命名为kafka-node-1。

2. 修改config/server.properties配置文件：

   The id of the broker. This must be set to a unique integer for each broker.

   kafka节点数字标识，集群内具有唯一性

   broker.id=1

   The address the socket server listens on. If not configured, the host name will be equal to the value of

   java.net.InetAddress.getCanonicalHostName(), with PLAINTEXT listener name, and port 9092.

   FORMAT:

   listeners = listener_name://host_name:port

   EXAMPLE:

   listeners = PLAINTEXT://your.host.name:9092

   监听器 9091为本地端口，如果冲突，请重新指定

   listeners=PLAINTEXT://:9091

   A comma separated list of directories under which to store log files

   数据文件路径，如果不存在，会自动创建

   log.dirs=E:/cluster/kafka-node-1/data

   Zookeeper connection string (see zookeeper docs for details).

   This is a comma separated host:port pairs, each corresponding to a zk

   server. e.g. "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002".

   You can also append an optional chroot string to the urls to specify the

   root directory for all kafka znodes.

   ZooKeeper软件连接地址，2181为默认的ZK端口号 /kafka 为ZK的管理节点

   zookeeper.connect=localhost:2181/kafka

   Timeout in ms for connecting to zookeeper

   zookeeper.connection.timeout.ms=18000

   The maximum size of a log segment file. When this size is reached a new log segment will be created.

   log.segment.bytes=190
   log.flush.interval.messages=2
   log.index.interval.bytes=17

   The interval at which log segments are checked to see if they can be deleted according

   to the retention policies

   log.retention.check.interval.ms=300000

   The following configuration specifies the time, in milliseconds, that the GroupCoordinator will delay the initial consumer rebalance.

   The rebalance will be further delayed by the value of group.initial.rebalance.delay.ms as new members join the group, up to a maximum of max.poll.interval.ms.

   The default value for this is 3 seconds.

   We override this to 0 here as it makes for a better out-of-the-box experience for development and testing.

   However, in production environments the default value of 3 seconds is more suitable as this will help to avoid unnecessary, and potentially expensive, rebalances during application startup.

   group.initial.rebalance.delay.ms=0

3. 将kafka-node-1文件夹复制两份，分别重命名为kafka-node-2，kafka-node-3。

4. 分别修改kafka-node-2，kafka-node-3文件夹中的server.properties配置文件：

   • 将broker.id=1改为broker.id=2，broker.id=3；
   • 将9091改为9092，9093（如端口冲突，请重新设置）；
   • 将kafka-node-1改为kafka-node-2，kafka-node-3。

封装启动脚本

由于启动Kafka集群前需先启动ZooKeeper，并且Kafka集群包含多个节点，因此启动过程较为繁琐。为此，我们将启动指令封装进批处理文件中：

1. 在kafka-zookeeper文件夹下创建zk.cmd批处理文件。

2. 在zk.cmd文件中添加启动命令：

   call bin/windows/zookeeper-server-start.bat config/zookeeper.properties
   

3. 在kafka-node-1，kafka-node-2，kafka-node-3文件夹下分别创建kfk.cmd批处理文件。

4. 在kfk.cmd文件中添加启动命令：

   call bin/windows/kafka-server-start.bat config/server.properties
   

5. 在cluster文件夹下创建cluster.cmd批处理文件，用于启动Kafka集群。

6. 在cluster.cmd文件中添加启动命令：

   cd kafka-zookeeper
   start zk.cmd
   ping 127.0.0.1 -n 10 >nul
   cd ../kafka-node-1
   start kfk.cmd
   cd ../kafka-node-2
   start kfk.cmd
   cd ../kafka-node-3
   start kfk.cmd
   

7. 在cluster文件夹下创建cluster-clear.cmd批处理文件，用于清理和重置Kafka数据。

8. 在cluster-clear.cmd文件中添加清理命令：

   cd kafka-zookeeper
   rd /s /q data
   cd ../kafka-node-1
   rd /s /q data
   cd ../kafka-node-2
   rd /s /q data
   cd ../kafka-node-3
   rd /s /q data
   

9. 双击执行cluster.cmd文件以启动Kafka集群。

启动集群命令后，会打开多个黑窗口，每个窗口代表一个Kafka服务，请勿关闭这些窗口，否则对应的Kafka服务将会停止。如果启动过程中出现错误，通常是由于ZooKeeper与Kafka之间的同步问题，请先执行cluster-clear.cmd文件，然后再执行cluster.cmd文件即可。