zookeeper對外提供分佈式協調服務，我們的分佈式應用，通過zookeeper可以很輕鬆的實現協調調度
zookeeper經常組成集羣提供服務，如下圖所示，集羣內各主機之間互聯互通，通過選舉產生leader，即使有主機因意外宕機，剩餘的主機也能選舉出一臺作爲leader繼續對外提供服務
更多細節可以查看apach的官方描述
我們有時候自己本地調試服務需要zookeeper提供服務，但是有沒有太多資源使用，可以選擇安裝單機版zookeeper
準備工作：安裝Java環境，配置path
1.下載zookeeper安裝包,本次使用3.6.0版本，可以去官網下載自己需要的版本
wget https://downloads.apache.org/zookeeper/zookeeper-3.6.0/apache-zookeeper-3.6.0-bin.tar.gz
2.解壓tar包
tar -zxvf apache-zookeeper-3.6.0-bin.tar.gz
3.進入解壓好的文件夾，並複製一份配置文件
cd /usr/local/zookeeper/apache-zookeeper-3.6.0/conf
cp zoo_sample.cfg zoo.cfg
4.編輯配置文件
vi coo.cfg
配置文件如下，修改dataDir和dataLogDir
其中dataDir裏需要創建一個myid文件，裏面配置的當前服務的id編號，本例子裏把myid設爲了2181
dataLogDir裏是日誌文件，如果缺少目錄文件夾及文件，請自己補全
# 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=/usr/local/zookeeper/apache-zookeeper-3.6.0/data
dataLogDir=/usr/local/zookeeper/apache-zookeeper-3.6.0/logs
# 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
5.啓動zookeeper
/usr/local/zookeeper/apache-zookeeper-3.6.0/bin/zkServer.sh start
啓動成功顯示如下
/usr/local/jdk1.8.0_251/bin/java
ZooKeeper JMX enabled by default
Using config: /usr/local/zookeeper/apache-zookeeper-3.6.0/bin/../conf/zoo.cfg
Starting zookeeper ... STARTED
6.如果報Java環境的錯誤就進入/usr/local/zookeeper/apache-zookeeper-3.6.0/bin文件夾修改啓動文件
在#!/usr/bin/env bash下添加jdk路徑，如果啓動不報錯可以不配置這項
#!/usr/bin/env bash
export=/usr/local/jdk1.8.0_251/bin:$PATH