zookeeper的搭建方式
zookeeper有三種安裝方式：
- 單機模式：zookeeper只運行在一臺服務器上，適用于測試環境
- 偽集群模式：在一臺物理機上運行多個zookeeper實例
- 集群模式：zookeeper運行于一個集群上，適用于生產環境，這個計算機集群被稱為一個"集合體"（ensemble）
單機模式搭建
下載zookeeper
官網：http://mirror.bit.edu.cn/apache/zookeeper/
解壓到安裝目錄
更改配置文件
在conf目錄下，新建zoo.cfg
tickTime=2000
dataDir=/usr/local/zk/data
dataLogDir=/usr/local/zk/dataLog
clientPort=2181
配置環境變量
vi .bash_profile
添加后面兩行的內容
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
啟動zookeeper
在zookeeper的bin目錄下，管理員啟動
sudo sh zkServer.sh start
響應的，關閉：
sudo sh zkServer.sh stop
偽集群模式搭建
要在一臺機器上的部署3個server，我們使用的是：每個配置文檔模擬一臺機器，實現單臺機器上運行多個zookeeper實例。
必須保證的是：每個配置文檔的端口號、dataDir都不能沖突！！！
搭建3個server
按照一下路徑建立3個server:
sanbiandeMacBook-Pro:zookeeper sanbian$ tree -d -L 2
.
├── server1
│ ├── data
│ ├── dataLog
│ └── zk
├── server2
│ ├── data
│ ├── dataLog
│ └── zk
└── server3
├── data
├── dataLog
└── zk
12 directories
配置文檔 zoo.cfg
dir相對配置，clientPort也響應配置為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
各個配置項的含義
tickTime=2000
zookeeper服務器之間或客戶端與服務器之間維持心跳的時間間隔，每隔tickTime時間就會發送一個心跳。
initLimit
配置zookeeper接受客戶端（zookeeper服務器集群中連接到Leader的Follower服務器）初始化連接時最長能忍受多少個心跳時間間隔數。當已超過initLimit*tickTime長度后，zookeeperr服務器若還沒有收到客戶端的返回信息，則表明客戶端連接失敗。
syncLimit
配置Leader與Follower之間發送消息，請求和應答時間長度，最長不能超過syncLimit*tickTime的時間長度
dataDir
zookeeper保存數據的目錄，默認情況下，寫數據的日志也保存在這個目錄
dataLogDir
若沒有的話，則用dataDir.
zookeeper的持久化都存儲在這個目錄里。
dataLogDir放的是順序日志（WAL），而dataDir放的是內存數據結構的snapshot,便于快速回復和達到性能最大化。
clientPort
zookeeper服務器監聽的端口，以接受客戶端的訪問請求。
server.A=B:C:D
- A:是一個數字，表示這是第幾號服務器
- B:這個服務器的ip地址。
- C:這個服務器與集群中的Leader服務器交換信息的端口
- D:萬一集群中的Leader服務偽集群器掛了，需要一個端口來重新進行選舉新的Leader，此端口就是用來執行選舉時服務器相互通信的端口。如果是偽集群的配置方式，由于B都是一樣的，所以不同zookeeper實例通信端口號不能一樣，所以要給它們分配不同的端口號。
在data下面新建myid文檔，對應到server.n
sanbiandeMacBook-Pro:zookeeper sanbian$ cd server1/data
sanbiandeMacBook-Pro:data sanbian$ echo "1" myid
啟動服務
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
查看啟動狀態
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$
關閉一個server,看其他server狀態
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，關閉掉Server1后，server2自動成為了leader
關閉2個server,啟動一個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.
產生異常信息的原因是由于Zookeeper 服務的每個實例都擁有全局配置信息，他們在啟動的時候會隨時隨地的進行Leader選舉操作。此時，第一個啟動的Zookeeper需要和另外兩個 Zookeeper實例進行通信。但是，另外兩個Zookeeper實例還沒有啟動起來，因此就產生了這的異樣信息。
如果將配置文件zoo.cfg里的關聯其他server的配置項去掉，再重新啟動查看狀態
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
這樣就變成了單機模式（獨立模式）。
所以在啟動三個服務時，先啟動一個服務也會出現這樣的異常，等到第二個啟動成功后，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
這個時候再關掉一個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.
在選舉leader時，找不到可以通信的Server，就又異常了。
如果先關閉掉follower,也是一樣的狀態。
遇到的坑
Error contacting service. It is probably not running.
網上查了很多辦法，都沒有解決。后來一句話點醒了我，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
~
很明顯了吧。我之前的zoo.cfg是自己寫進去的，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。。就解決了！所以有錯還是要先看自己的報錯日志啊
