ZooKeeper在分布式系统上用的非常多，包括HDFS, HBase, Kafka, YARN, ClickHouse等都借助ZooKeeper实现服务的高可用性。这里介绍ZooKeeper分布式集群的安装和配置。
安装JDK
首先需要安装JDK
下载安装包
目前最新的ZooKeeper稳定版是3.6.3，可以通过以下地址找到离自己最近的镜像站点下载安装包。
https://www.apache.org/dyn/closer.lua/zookeeper/zookeeper-3.6.3/apache-zookeeper-3.6.3-bin.tar.gz
比如，清华大学的镜像下载地址。
https://mirrors.tuna.tsinghua.edu.cn/apache/zookeeper/zookeeper-3.6.3/apache-zookeeper-3.6.3-bin.tar.gz
下载后校验一下安装包的完整性，可以与官网sha512值比对。
[root@centos1 ~]# sha512sum apache-zookeeper-3.6.3-bin.tar.gz
3f7b1b7d9cf5647d52ad0076c922e108fa956e986b5624667c493cf6d8ff09d3ca88f623c79a799fe49c72e868cb3c9d0f77cb69608de74a183b2cbad10bc827 apache-zookeeper-3.6.3-bin.tar.gz
安装和配置
# 解压
tar -zxf apache-zookeeper-3.6.3-bin.tar.gz -C /usr/local
chown -R root:root /usr/local/apache-zookeeper-3.6.3-bin
ln -s /usr/local/apache-zookeeper-3.6.3-bin /usr/local/zookeeper
# 设置环境变量
vi /etc/profile
# ZooKeeper
export ZOOKEEPER_HOME=/usr/local/zookeeper
export PATH=$PATH:$ZOOKEEPER_HOME/bin
source /etc/profile
# 修改配置文件
cd /usr/local/zookeeper/conf
cp zoo_sample.cfg zoo.cfg
vi zoo.cfg
将zoo.cfg按照实际情况修改，比如以下是我三节点集群的配置。
# 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=/var/lib/zookeeper
dataLogDir=/var/lib/zookeeper
# 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
server.1=centos1:2888:3888
server.2=centos2:2888:3888
server.3=centos3:2888:3888
# 创建数据目录
mkdir -p /var/lib/zookeeper
# centos1
echo "1" > /var/lib/zookeeper/myid
# centos2
echo "2" > /var/lib/zookeeper/myid
# centos3
echo "3" > /var/lib/zookeeper/myid
# 启动ZooKeeper
zkServer.sh start
# 查询ZooKeeper服务状态
zkServer.sh status
# 客户端连接ZooKeeper
zkCli.sh -server 127.0.0.1:2181
可以看到启动了两个follower，一个leader
测试ZooKeeper
ls /
# 创建一个znode，关联字符串为my_data
create /zk_test my_data
# 获取这个znode关联的数据
get /zk_test
# 重新设置znode的关联数据
set /zk_test junk
# 删除znode
delete /zk_test
欢迎关注我的公众号“九万里大数据”，原创技术文章第一时间推送。
欢迎访问原创技术博客网站 jwldata.com，排版更清晰，阅读更爽快。
