zookeeper的搭建方式
zookeeper有三种安装方式：
- 单机模式：zookeeper只运行在一台服务器上，适用于测试环境
- 伪集群模式：在一台物理机上运行多个zookeeper实例
- 集群模式：zookeeper运行于一个集群上，适用于生产环境，这个计算机集群被称为一个"集合体"（ensemble）
单机模式搭建
下载zookeeper
官网：http://mirror.bit.edu.cn/apache/zookeeper/
解压到安装目录
更改配置文件
在conf目录下，新建zoo.cfg
tickTime=2000
dataDir=/usr/local/zk/data
dataLogDir=/usr/local/zk/dataLog
clientPort=2181
配置环境变量
vi .bash_profile
添加后面两行的内容
export M2_HOME=/Users/sanbian/Documents/soft/apache-maven-3.3.9/
export PATH=$PATH:$M2_HOME/bin
export ZOOKEEPER_HOME=/usr/local/zk
export PATH=$PATH:$ZOOKEEPER_HOME/bin
启动zookeeper
在zookeeper的bin目录下，管理员启动
sudo sh zkServer.sh start
响应的，关闭：
sudo sh zkServer.sh stop
伪集群模式搭建
要在一台机器上的部署3个server，我们使用的是：每个配置文档模拟一台机器，实现单台机器上运行多个zookeeper实例。
必须保证的是：每个配置文档的端口号、dataDir都不能冲突！！！
搭建3个server
按照一下路径建立3个server:
sanbiandeMacBook-Pro:zookeeper sanbian$ tree -d -L 2
.
├── server1
│ ├── data
│ ├── dataLog
│ └── zk
├── server2
│ ├── data
│ ├── dataLog
│ └── zk
└── server3
├── data
├── dataLog
└── zk
12 directories
配置文档 zoo.cfg
dir相对配置，clientPort也响应配置为2181，2182，2183
# 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=/Users/sanbian/Documents/soft/zookeeper/server3/data
dataLogDir=/Users/sanbian/Documents/soft/zookeeper/server3/dataLog
# the port at which the clients will connect
clientPort=2183
# 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=127.0.0.1:8881:7771
server.2=127.0.0.1:8882:7772
server.3=127.0.0.1:8883:7773
各个配置项的含义
tickTime=2000
zookeeper服务器之间或客户端与服务器之间维持心跳的时间间隔，每隔tickTime时间就会发送一个心跳。
initLimit
配置zookeeper接受客户端（zookeeper服务器集群中连接到Leader的Follower服务器）初始化连接时最长能忍受多少个心跳时间间隔数。当已超过initLimit*tickTime长度后，zookeeperr服务器若还没有收到客户端的返回信息，则表明客户端连接失败。
syncLimit
配置Leader与Follower之间发送消息，请求和应答时间长度，最长不能超过syncLimit*tickTime的时间长度
dataDir
zookeeper保存数据的目录，默认情况下，写数据的日志也保存在这个目录
dataLogDir
若没有的话，则用dataDir.
zookeeper的持久化都存储在这个目录里。
dataLogDir放的是顺序日志（WAL），而dataDir放的是内存数据结构的snapshot,便于快速回复和达到性能最大化。
clientPort
zookeeper服务器监听的端口，以接受客户端的访问请求。
server.A=B:C:D
- A:是一个数字，表示这是第几号服务器
- B:这个服务器的ip地址。
- C:这个服务器与集群中的Leader服务器交换信息的端口
- D:万一集群中的Leader服务伪集群器挂了，需要一个端口来重新进行选举新的Leader，此端口就是用来执行选举时服务器相互通信的端口。如果是伪集群的配置方式，由于B都是一样的，所以不同zookeeper实例通信端口号不能一样，所以要给它们分配不同的端口号。
在data下面新建myid文档，对应到server.n
sanbiandeMacBook-Pro:zookeeper sanbian$ cd server1/data
sanbiandeMacBook-Pro:data sanbian$ echo "1" myid
启动服务
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
sanbiandeMacBook-Pro:zookeeper sanbian$ server1/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server1/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
查看启动状态
sanbiandeMacBook-Pro:zookeeper sanbian$ server1/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server1/zk/bin/../conf/zoo.cfg
Mode: follower
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Mode: follower
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Mode: leader
sanbiandeMacBook-Pro:zookeeper sanbian$
关闭一个server,看其他server状态
sanbiandeMacBook-Pro:zookeeper sanbian$ server1/zk/bin/zkServer.sh stop
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server1/zk/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
sanbiandeMacBook-Pro:zookeeper sanbian$ server1/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server1/zk/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Mode: leader
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Mode: follower
可以看到，关闭掉Server1后，server2自动成为了leader
关闭2个server,启动一个server
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.
产生异常信息的原因是由于Zookeeper 服务的每个实例都拥有全局配置信息，他们在启动的时候会随时随地的进行Leader选举操作。此时，第一个启动的Zookeeper需要和另外两个 Zookeeper实例进行通信。但是，另外两个Zookeeper实例还没有启动起来，因此就产生了这的异样信息。
如果将配置文件zoo.cfg里的关联其他server的配置项去掉，再重新启动查看状态
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Mode: standalone
这样就变成了单机模式（独立模式）。
所以在启动三个服务时，先启动一个服务也会出现这样的异常，等到第二个启动成功后，便正常了。
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh start
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Mode: leader
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Mode: follower
这个时候再关掉一个Server
sanbiandeMacBook-Pro:zookeeper sanbian$ server3/zk/bin/zkServer.sh stop
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server3/zk/bin/../conf/zoo.cfg
Stopping zookeeper ... STOPPED
sanbiandeMacBook-Pro:zookeeper sanbian$ server2/zk/bin/zkServer.sh status
ZooKeeper JMX enabled by default
Using config: /Users/sanbian/Documents/soft/zookeeper/server2/zk/bin/../conf/zoo.cfg
Error contacting service. It is probably not running.
在选举leader时，找不到可以通信的Server，就又异常了。
如果先关闭掉follower,也是一样的状态。
遇到的坑
Error contacting service. It is probably not running.
网上查了很多办法，都没有解决。后来一句话点醒了我，看日志呀！！！日志在哪里呢？？？zookeeper.out
sanbiandeMacBook-Pro:zookeeper sanbian$ vi server2/zk/bin/zookeeper.out
2017-09-06 16:49:41,767 [myid:] - INFO [main:QuorumPeerConfig@134] - Reading configuration from: ../conf/zoo3.cfg
2017-09-06 16:49:41,777 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: localhost to address: localhost/127.0.0.1
2017-09-06 16:49:41,778 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: localhost to address: localhost/127.0.0.1
2017-09-06 16:49:41,778 [myid:] - INFO [main:QuorumPeer$QuorumServer@167] - Resolved hostname: localhost to address: localhost/127.0.0.1
2017-09-06 16:49:41,779 [myid:] - ERROR [main:QuorumPeerMain@85] - Invalid config, exiting abnormally
org.apache.zookeeper.server.quorum.QuorumPeerConfig$ConfigException: Error processing ../conf/zoo3.cfg
at org.apache.zookeeper.server.quorum.QuorumPeerConfig.parse(QuorumPeerConfig.java:154)
at org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:101)
at org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:78)
Caused by: java.lang.IllegalArgumentException: initLimit is not set
at org.apache.zookeeper.server.quorum.QuorumPeerConfig.parseProperties(QuorumPeerConfig.java:355)
at org.apache.zookeeper.server.quorum.QuorumPeerConfig.parse(QuorumPeerConfig.java:150)
... 2 more
Invalid config, exiting abnormally
~
很明显了吧。我之前的zoo.cfg是自己写进去的，少了initLimit
tickTime=2000
dataDir=/Users/sanbian/Documents/soft/zookeeper/server3/data
dataLogDir=/Users/sanbian/Documents/soft/zookeeper/server3/dataLog
clientPort=2183
server.1=127.0.0.1:8881:7771
server.2=127.0.0.1:8882:7772
server.3=127.0.0.1:8883:7773
按照zoo_sample.cfg更改：
# 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=/tmp/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
然后。。就解决了！所以有错还是要先看自己的报错日志啊
