ZooKeeper的伪分布式集群搭建以及真分布式集群搭建
zk集群的一些基本概念zookeeper集群搭建：
[*]zk集群，主从节点，心跳机制（选举模式）
[*]配置数据文件 myid 1/2/3 对应 server.1/2/3
[*]通过 zkCli.sh -server : 命令检测集群是否配置成功
和其他大多数集群结构一样，zookeeper集群也是主从结构。搭建集群时，机器数量最低也是三台，因为小于三台就无法进行选举。选举就是当集群中的master节点挂掉之后，剩余的两台机器会进行选举，在这两台机器中选举出一台来做master节点。而当原本挂掉的master恢复正常后，也会重新加入集群当中。但是不会再作为master节点，而是作为slave节点。如下：
http://i2.运维网.com/images/blog/201804/24/30d6a17c5e8a9e057a0c4a820644a863.png
单机伪分布式搭建zookeeper集群
本节介绍单机伪分布式的zookeeper安装，官方下载地址如下：
https://archive.apache.org/dist/zookeeper/
我这里使用的是3.4.11版本，所以找到相应的版本点击进去，复制到.tar.gz的下载链接到Linux上进行下载。命令如下：
# cd /usr/local/src/
# wget https://archive.apache.org/dist/zookeeper/zookeeper-3.4.11/zookeeper-3.4.11.tar.gz
下载完成之后将其解压到/usr/local/目录下：
# tar -zxvf zookeeper-3.4.11.tar.gz -C /usr/local/
# cd ../zookeeper-3.4.11/
# ls
bin dist-maven lib README_packaging.txtzookeeper-3.4.11.jar.asc
build.xmldocs LICENSE.txtrecipes zookeeper-3.4.11.jar.md5
conf ivysettings.xmlNOTICE.txt src zookeeper-3.4.11.jar.sha1
contrib ivy.xml README.md zookeeper-3.4.11.jar
#
然后给目录重命名一下：
# cd /usr/local/
# mv zookeeper-3.4.11/ zookeeper00
接着进行一系列的配置：
# cd zookeeper00/
# cd conf/
# cp zoo_sample.cfg zoo.cfg# 拷贝官方提供的模板配置文件
# vim zoo.cfg# 增加或修改成如下内容
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper00/dataDir
dataLogDir=/usr/local/zookeeper00/dataLogDir
clientPort=2181
4lw.commands.whitelist=*
server.1=192.168.190.129:2888:3888# master节点，ip后面跟的是集群通信的端口
server.2=192.168.190.129:2889:3889
server.3=192.168.190.129:2890:3890
# cd ../
# mkdir {dataDir,dataLogDir}
# cd dataDir/
# vim myid# 配置该节点的id
1
#
配置完之后，拷贝多个目录出来，因为是单机的伪分布式所以需要在一台机器上安装多个zookeeper：
# cp zookeeper00 zookeeper01 -rf
# cp zookeeper00 zookeeper02 -rf
配置 zookeeper01：
# cd zookeeper01/conf/
# vim zoo.cfg# 修改内容如下
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper01/dataDir
dataLogDir=/usr/local/zookeeper01/dataLogDir
clientPort=2182# 端口号必须要修改
4lw.commands.whitelist=*
server.1=192.168.190.129:2888:3888
server.2=192.168.190.129:2889:3889
server.3=192.168.190.129:2890:3890
# cd ../dataDir/
# vim myid
2
#
配置 zookeeper02：
# cd zookeeper02/conf/
# vim zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper02/dataDir
dataLogDir=/usr/local/zookeeper02/dataLogDir
clientPort=2183# 端口号必须要修改
4lw.commands.whitelist=*
server.1=192.168.190.129:2888:3888
server.2=192.168.190.129:2889:3889
server.3=192.168.190.129:2890:3890
# cd ../dataDir/
# vim myid
3
#
以上就在单机上配置好三个zookeeper集群节点了，现在我们来测试一下，这个伪分布式的zookeeper集群能否正常运作起来：
# cd /usr/local/zookeeper00/bin/
# ./zkServer.sh start# 启动第一个节点
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper00/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
# netstat -lntp |grep java# 查看监听的端口
tcp6 0 0 192.168.190.129:3888 :::* LISTEN 3191/java# 集群通信的端口
tcp6 0 0 :::44793 :::* LISTEN 3191/java
tcp6 0 0 :::2181 :::* LISTEN 3191/java
# cd ../../zookeeper01/bin/
# ./zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper01/bin/../conf/zoo.cfg# 启动第二个节点
Starting zookeeper ... STARTED
# cd ../../zookeeper02/bin/
# ./zkServer.sh start# 启动第三个节点
# netstat -lntp |grep java # 查看监听的端口
tcp6 0 0 192.168.190.129:2889 :::* LISTEN 3232/java
tcp6 0 0 :::48463 :::* LISTEN 3232/java
tcp6 0 0 192.168.190.129:3888 :::* LISTEN 3191/java
tcp6 0 0 192.168.190.129:3889 :::* LISTEN 3232/java
tcp6 0 0 192.168.190.129:3890 :::* LISTEN 3286/java
tcp6 0 0 :::44793 :::* LISTEN 3191/java
tcp6 0 0 :::60356 :::* LISTEN 3286/java
tcp6 0 0 :::2181 :::* LISTEN 3191/java
tcp6 0 0 :::2182 :::* LISTEN 3232/java
tcp6 0 0 :::2183 :::* LISTEN 3286/java
# jps# 查看进程
3232 QuorumPeerMain
3286 QuorumPeerMain
3191 QuorumPeerMain
3497 Jps
#
如上，可以看到，三个节点都正常启动成功了，接下来我们进入客户端，创建一些znode，看看是否会同步到集群中的其他节点上去：
# ./zkCli.sh -server localhost:2181# 登录第一个节点的客户端
ls /
create /data test-data
Created /data
ls /
quit
# ./zkCli.sh -server localhost:2182# 登录第二个节点的客户端
ls /# 可以查看到我们在第一个节点上创建的znode，代表集群中的节点能够正常同步数据
get /data# 数据也是一致的
test-data
cZxid = 0x100000002
ctime = Tue Apr 24 18:35:56 CST 2018
mZxid = 0x100000002
mtime = Tue Apr 24 18:35:56 CST 2018
pZxid = 0x100000002
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 9
numChildren = 0
quit
# ./zkCli.sh -server localhost:2183# 登录第三个节点的客户端
ls /# 第三个节点也能查看到我们在第一个节点上创建的znode
get /data# 数据也是一致的
test-data
cZxid = 0x100000002
ctime = Tue Apr 24 18:35:56 CST 2018
mZxid = 0x100000002
mtime = Tue Apr 24 18:35:56 CST 2018
pZxid = 0x100000002
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 9
numChildren = 0
quit
#
查看集群的状态、主从信息需要使用 ./zkServer.sh status 命令，但是多个节点的话，逐个查看有些费劲，所以我们写一个简单的shell脚本来批量执行命令。如下：
# vim checked.sh# 脚本内容如下
#!/bin/bash
/usr/local/zookeeper00/bin/zkServer.sh status
/usr/local/zookeeper01/bin/zkServer.sh status
/usr/local/zookeeper02/bin/zkServer.sh status
# sh ./checked.sh# 执行脚本
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper00/bin/../conf/zoo.cfg
Mode: follower# 从节点
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper01/bin/../conf/zoo.cfg
Mode: leader # 主节点
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper02/bin/../conf/zoo.cfg
Mode: follower
#
到此为止，我们就成功完成了单机zookeeper伪分布式集群的搭建，并且也测试成功了。
搭建zookeeper分布式集群
接下来，我们使用三台虚拟机来搭建zookeeper真实分布式集群，机器的ip地址如下：
[*]192.168.190.128
[*]192.168.190.129
[*]192.168.190.130
注：三台机器都必须具备java的运行环境，并且关闭或清空防火墙规则，不想关闭防火墙的话，就需要去配置相应的防火墙规则
首先配置一下系统的hosts文件：
# vim /etc/hosts
192.168.190.128 zk000
192.168.190.129 zk001
192.168.190.130 zk002
把之前做伪分布式实验机器上的其他zookeeper目录删除掉，并把zookeeper目录使用rsync同步到其他机器上。如下：
# cd /usr/local/
# rm -rf zookeeper01
# rm -rf zookeeper02
# mv zookeeper00/ zookeeper
# rsync -av /usr/local/zookeeper/ 192.168.190.128:/usr/local/zookeeper/
# rsync -av /usr/local/zookeeper/ 192.168.190.130:/usr/local/zookeeper/
然后逐个在三台机器上都配置一下环境变量，如下：
# vim .bash_profile# 增加如下内容
export ZOOKEEPER_HOME=/usr/local/zookeeper
PATH=$PATH:$HOME/bin:$JAVA_HOME/bin:$ZOOKEEPER_HOME/bin
export PATH
# source .bash_profile
逐个修改配置文件，zk000：
# cd /usr/local/zookeeper/conf/
# vim zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper/dataDir
dataLogDir=/usr/local/zookeeper/dataLogDir
clientPort=2181
4lw.commands.whitelist=*
server.1=192.168.190.128:2888:3888# 默认server.1为master节点
server.2=192.168.190.129:2888:3888
server.3=192.168.190.130:2888:3888
# cd ../dataDir/
# vim myid
1
#
zk001：
# cd /usr/local/zookeeper/conf/
# vim zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper/dataDir
dataLogDir=/usr/local/zookeeper/dataLogDir
clientPort=2181
4lw.commands.whitelist=*
server.1=192.168.190.128:2888:3888# 默认server.1为master节点
server.2=192.168.190.129:2888:3888
server.3=192.168.190.130:2888:3888
# cd ../dataDir/
# vim myid
2
#
zk002：
# cd /usr/local/zookeeper/conf/
# vim zoo.cfg
tickTime=2000
initLimit=10
syncLimit=5
dataDir=/usr/local/zookeeper/dataDir
dataLogDir=/usr/local/zookeeper/dataLogDir
clientPort=2181
4lw.commands.whitelist=*
server.1=192.168.190.128:2888:3888# 默认server.1为master节点
server.2=192.168.190.129:2888:3888
server.3=192.168.190.130:2888:3888
# cd ../dataDir/
# vim myid
3
#
配置完成之后，启动三台机器的zookeeper服务：
# zkServer.sh start
# zkServer.sh start
# zkServer.sh start
启动成功后，查看三个机器的集群状态信息：
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: leader
#
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
#
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
#
然后我们来测试创建znode是否会同步，进入192.168.190.128机器的客户端：
# zkCli.sh -server 192.168.190.128:2181
ls /
create /real-culster real-data
Created /real-culster
ls /
get /real-culster
real-data
cZxid = 0x300000002
ctime = Tue Apr 24 20:48:32 CST 2018
mZxid = 0x300000002
mtime = Tue Apr 24 20:48:32 CST 2018
pZxid = 0x300000002
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 9
numChildren = 0
quit
进入192.168.190.129机器的客户端
# zkCli.sh -server 192.168.190.129:2181
ls /
get /real-culster
real-data
cZxid = 0x300000002
ctime = Tue Apr 24 20:48:32 CST 2018
mZxid = 0x300000002
mtime = Tue Apr 24 20:48:32 CST 2018
pZxid = 0x300000002
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 9
numChildren = 0
quit
进入192.168.190.130机器的客户端
# zkCli.sh -server 192.168.190.130:2181
ls /
get /real-culster
real-data
cZxid = 0x300000002
ctime = Tue Apr 24 20:48:32 CST 2018
mZxid = 0x300000002
mtime = Tue Apr 24 20:48:32 CST 2018
pZxid = 0x300000002
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 9
numChildren = 0
quit
从以上的测试可以看到，在zookeeper分布式集群中，我们在任意一个节点创建的znode都会被同步的集群中的其他节点上，数据也会被一并同步。所以到此为止，我们的zookeeper分布式集群就搭建成功了。
测试集群角色以及选举
以上我们只是测试了znode的同步，还没有测试集群中的节点选举，所以本节就来测试一下，当master节点挂掉之后看看slave节点会不会通过选举坐上master的位置。首先我们来把master节点的zookeeper服务给停掉：
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: leader
# zkServer.sh stop
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
#
这时到其他两台机器上进行查看，可以看到有一台已经成为master节点了：
# zkServer.sh status# 可以看到zk002这个节点成为了master节点
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: leader
#
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
#
然后再把停掉的节点启动起来，可以看到，该节点重新加入了集群，但是此时是以slave角色存在，而不会以master角色存在：
# zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: follower
#
可以看到，zk002这个节点依旧是master角色，不会被取代，所以只有在选举的时候集群中的节点才会切换角色：
# zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/bin/../conf/zoo.cfg
Mode: leader
#
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