一、Zookeeper 介绍
Apache ZooKeeper 是一个开放源码的分布式应用程序协调组件，是 Hadoop 和 Hbase 的重要组件。它是一个为分布式应用提供一致性服务的软件，提供的功能包括：配置维护、域名服务、分布式同步、组服务等。
在微服务项目开发中 ZooKeeper 主要的角色是当做服务注册中心存在，我们将编写好的服务注册至 ZooKeeper 即可。
二、ZooKeeper 安装
环境准备
ZooKeeper 在 Java 中运行，版本 1.8 或更高（JDK 8 LTS，JDK 11 LTS，JDK 12 - Java 9 和 10 不支持）
下载
ZooKeeper 下载地址：
- https://zookeeper.apache.org/releases.html#download
- https://archive.apache.org/dist/zookeeper/
安装
将文件上传至 Linux 服务器。
单机版
创建目录/解压
创建 zookeeper 目录。
mkdir -p /usr/local/zookeeper
将文件解压至该目录。
tar -zxvf apache-zookeeper-3.6.1-bin.tar.gz -C /usr/local/zookeeper/
创建数据目录、日志目录。
mkdir -p /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/data
mkdir -p /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/log
修改配置文件
# 进入配置文件目录 cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/conf/ # ZooKeeper 启动默认加载名为 zoo.cfg 的配置文件，复制一份命名为 zoo.cfg cp zoo_sample.cfg zoo.cfg # 修改配置文件 vi zoo.cfg
主要修改数据目录dataDir、日志目录dataLogDir两处即可，修改结果如下：
# The number of milliseconds of each tick tickTime=2000 # The number of ticks that the initial # synchronization phase can take initLimit=10 # The number of ticks that can pass between # sending a request and getting an acknowledgement syncLimit=5 # the directory where the snapshot is stored. # do not use /tmp for storage, /tmp here is just # example sakes. dataDir=/usr/local/zookeeper/apache-zookeeper-3.6.1-bin/data dataLogDir=/usr/local/zookeeper/apache-zookeeper-3.6.1-bin/log # the port at which the clients will connect clientPort=2181 # the maximum number of client connections. # increase this if you need to handle more clients #maxClientCnxns=60 # # Be sure to read the maintenance section of the # administrator guide before turning on autopurge. # # http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance # # The number of snapshots to retain in dataDir #autopurge.snapRetainCount=3 # Purge task interval in hours # Set to "0" to disable auto purge feature #autopurge.purgeInterval=1 ## Metrics Providers # # https://prometheus.io Metrics Exporter #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider #metricsProvider.httpPort=7000 #metricsProvider.exportJvmInfo=true
启动/关闭
启动。
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/ bin/zkServer.sh start --------------------------------------------------------------------------------- ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Starting zookeeper ... STARTED
关闭。
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/ bin/zkServer.sh stop --------------------------------------------------------------------------------- ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Stopping zookeeper ... STOPPED
集群版
再准备两台机器，和刚才单机的机器加一起构成一个集群环境（如果电脑跑不动就改为一台机器跑三个进程的方式）。
创建目录/解压
创建 zookeeper 目录。
mkdir -p /usr/local/zookeeper
将文件解压至该目录。
tar -zxvf apache-zookeeper-3.6.1-bin.tar.gz -C /usr/local/zookeeper/
创建数据目录、日志目录。
mkdir -p /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/data
mkdir -p /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/log
myid 文件
在 data 目录下创建 myid 文件，文件中就只写个 1 即可，其他两个机器分别写 2和 3。
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/data/
vi myid
修改配置文件
# 进入配置文件目录 cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/conf/ # zookeeper 启动默认加载名为 zoo.cfg 的配置文件，所以复制一份命名为 zoo.cfg cp zoo_sample.cfg zoo.cfg # 修改配置文件 vi zoo.cfg
主要修改：
- 数据目录
dataDir - 日志目录
dataLogDir - 端口
clientPort（如果是一台机器的伪集群，需要修改 2181 端口，比如：2181、2182、2183） - 集群配置（如果是一台机器的伪集群，需要修改 2888 和 3888 的端口，比如：2888、2889、2890 和 3888、3889、3890）
# The number of milliseconds of each tick tickTime=2000 # The number of ticks that the initial # synchronization phase can take initLimit=10 # The number of ticks that can pass between # sending a request and getting an acknowledgement syncLimit=5 # the directory where the snapshot is stored. # do not use /tmp for storage, /tmp here is just # example sakes. dataDir=/usr/local/zookeeper/apache-zookeeper-3.6.1-bin/data dataLogDir=/usr/local/zookeeper/apache-zookeeper-3.6.1-bin/log # the port at which the clients will connect clientPort=2181 # the maximum number of client connections. # increase this if you need to handle more clients #maxClientCnxns=60 # # Be sure to read the maintenance section of the # administrator guide before turning on autopurge. # # http://zookeeper.apache.org/doc/current/zookeeperAdmin.html#sc_maintenance # # The number of snapshots to retain in dataDir #autopurge.snapRetainCount=3 # Purge task interval in hours # Set to "0" to disable auto purge feature #autopurge.purgeInterval=1 ## Metrics Providers # # https://prometheus.io Metrics Exporter #metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider #metricsProvider.httpPort=7000 #metricsProvider.exportJvmInfo=true # 集群配置 # server.1 中的 1 是 myid 文件中的内容，2888 用于集群内部通信，3888 用于选择 leader server.1=192.168.10.101:2888:3888 server.2=192.168.10.102:2888:3888 server.3=192.168.10.103:2888:3888
启动/关闭
启动。
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/ bin/zkServer.sh start ################################################################################# ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Starting zookeeper ... STARTED
关闭。
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/ bin/zkServer.sh stop ################################################################################# ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Stopping zookeeper ... STOPPED
集群状态查看
cd /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/ bin/zkServer.sh status ################################ 192.168.10.101 ################################ ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Client port found: 2181. Client address: localhost. Mode: follower ################################ 192.168.10.102 ################################ ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Client port found: 2181. Client address: localhost. Mode: leader ################################ 192.168.10.103 ################################ ZooKeeper JMX enabled by default Using config: /usr/local/zookeeper/apache-zookeeper-3.6.1-bin/bin/../conf/zoo.cfg Client port found: 2181. Client address: localhost. Mode: follower
看到以上信息说明 ZooKeeper 集群环境已搭建成功，接下来就可以通过 RPC 框架对接 ZooKeeper，将 ZooKeeper 作为我们的注册中心来使用。点击获取 java微服务架构、spring全家桶视频教程。