一、Zookeeper功能简介
ZooKeeper 是一个开源的分布式协调服务,由雅虎创建,是 Google Chubby 的开源实现。分布式应用程序可以基于 ZooKeeper 实现诸如数据发布/订阅、负载均衡、命名服务、分布式协调/通知、集群管理、Master 选举、配置维护,名字服务、分布式同步、分布式锁和分布式队列等功能。
二、ZooKeeper基本概念
1、集群角色
一个 ZooKeeper 集群同一时刻只会有一个 Leader,其他都是 Follower 或 Observer。
ZooKeeper 配置很简单,每个节点的配置文件(zoo.cfg)都是一样的,只有 myid 文件不一样。myid 的值必须是 zoo.cfg中server.{数值} 的{数值}部分。
ZooKeeper 默认只有 Leader 和 Follower 两种角色,没有 Observer 角色。为了使用 Observer 模式,在任何想变成Observer的节点的配置文件中加入:peerType=observer 并在所有 server 的配置文件中,配置成 observer 模式的 server 的那行配置追加 :observer
三、ZooKeeper 的安装
1、下载安装(在datanode节点安装)
下载安装包
wget http://mirror.bit.edu.cn/apache/zookeeper/zookeeper-3.4.10/zookeeper-3.4.10.tar.gz
解压安装包
tar xf zookeeper-3.4.10.tar.gz
mv zookeeper-3.4.10 /usr/local/zookeeper
mkdir -p /home/zookeeper
zk01节点(datanode1)配置id
echo "1">/home/zookeeper/myid
zk02节点(datanode2)配置id
echo "2">/home/zookeeper/myid
zk03节点(datanode3)配置id
echo "3">/home/zookeeper/myid
2、配置ZooKeeper环境变量
编辑文件/etc/profile.d/zookeeper.sh
。
# ZOOKEEPER ENV
export ZOOKEEPER_HOME=/usr/local/zookeeper
export PATH=$PATH:$ZOOKEEPER_HOME/bin
使ZK环境变量生效。
source /etc/profile.d/zookeeper.sh
3、配置 zoo.cfg
编辑文件/usr/local/zookeeper/conf/zoo.cfg
。
# 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=/home/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
server.1=zk01:2888:3888
server.2=zk02:2888:3888
server.3=zk03:2888:3888
比较重要的配置如下: dataDir=/home/zookeeper server.1=zk01:2888:3888 server.2=zk02:2888:3888 server.3=zk03:2888:3888
4、启动各节点 ZK 服务
[root@datanode01 ~]# zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[root@datanode02 ~]# zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
[root@datanode03 ~]# zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
5、查看各节点启动状态和角色
[root@datanode01 ~]# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
[root@datanode02 ~]# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: leader
[root@datanode03 ~]# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
官方文档:https://zookeeper.apache.org/doc/current/zookeeperStarted.html