1.获取官方镜像
从dockerhub获取官方的zookeeper镜像：
docker pull zookeeper
2.了解镜像内容
拉取完镜像后，通过
docker inspect zookeeper
我们可以查看到关于该镜像的一些基本信息：
......"Env": [ "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/lib/jvm/java-1.8-openjdk/jre/bin:/usr/lib/jvm/java-1.8-openjdk/bin:/zookeeper-3.4.10/bin", "LANG=C.UTF-8", "JAVA_HOME=/usr/lib/jvm/java-1.8-openjdk/jre", "JAVA_VERSION=8u131", "JAVA_ALPINE_VERSION=8.131.11-r2", "ZOO_USER=zookeeper", "ZOO_CONF_DIR=/conf", "ZOO_DATA_DIR=/data", "ZOO_DATA_LOG_DIR=/datalog", "ZOO_PORT=2181", "ZOO_TICK_TIME=2000", "ZOO_INIT_LIMIT=5", "ZOO_SYNC_LIMIT=2", "ZOO_MAX_CLIENT_CNXNS=60", "ZOOCFGDIR=/conf"],"Cmd": [ "zkServer.sh", "start-foreground"],"Volumes": { "/data": {}, "/datalog": {}},"WorkingDir": "/zookeeper-3.4.10","Entrypoint": [ "/docker-entrypoint.sh"],...... 即，该zookeeper的版本是3.4.10，conf目录在/conf，基于该镜像启动的容器的entrypoint为
/docker-entrypoint.sh
默认传入的参数为
zkServer.sh start-foreground
基于该镜像启动一个容器：
docker run -d zookeeper
然后进入容器后，我们可以查看docker-entrypoint.sh的基本内容：
#!/bin/bashset -e# Allow the container to be started with `--user`if [ "$1" = 'zkServer.sh' -a "$(id -u)" = '0' ]; then chown -R "$ZOO_USER" "$ZOO_DATA_DIR" "$ZOO_DATA_LOG_DIR" exec su-exec "$ZOO_USER" "$0" "$@"fi# Generate the config only if it doesn't existif [ ! -f "$ZOO_CONF_DIR/zoo.cfg" ]; then CONFIG="$ZOO_CONF_DIR/zoo.cfg" echo "clientPort=$ZOO_PORT" >> "$CONFIG" echo "dataDir=$ZOO_DATA_DIR" >> "$CONFIG" echo "dataLogDir=$ZOO_DATA_LOG_DIR" >> "$CONFIG" echo "tickTime=$ZOO_TICK_TIME" >> "$CONFIG" echo "initLimit=$ZOO_INIT_LIMIT" >> "$CONFIG" echo "syncLimit=$ZOO_SYNC_LIMIT" >> "$CONFIG" echo "maxClientCnxns=$ZOO_MAX_CLIENT_CNXNS" >> "$CONFIG" for server in $ZOO_SERVERS; do echo "$server" >> "$CONFIG" donefi# Write myid only if it doesn't existif [ ! -f "$ZOO_DATA_DIR/myid" ]; then echo "${ZOO_MY_ID:-1}" > "$ZOO_DATA_DIR/myid"fiexec "$@" 可以看到，该脚本主要是用于设置启动zookeeper的用户，以及创建zoo.cfg配置文件。
看到其中有一段是：
for server in $ZOO_SERVERS; do echo "$server" >> "$CONFIG"done
# Write myid only if it doesn't existif [ ! -f "$ZOO_DATA_DIR/myid" ]; then echo "${ZOO_MY_ID:-1}" > "$ZOO_DATA_DIR/myid"fi 即只要传入ZOO_SERVERS参数，我们就可以设置各个zookeeper server节点的host信息，设置ZOO_MY_ID参数就可以写入本节点的serverID。
这一段脚本的作用使得该镜像可以很好地适配zk的不同模式：单机模式和集群模式（伪集群模式）。
3.在宿主机上搭建多节点集群模式的zookeeper
基于上述调研，我们可以明确搭建一个多节点的zookeeper集群需要的步骤如下：
(1) 获取zookeeper官方镜像
(2) 连通不同zk server节点所在容器之间的网络
(3) 对每个zk server节点设置相同的zoo.cfg，传入集群中各节点的host信息
(4) 设置各个zk server节点的ServerID（修改各自的$dataDir/myid文件）
(5) 启动集群, 并将端口2181映射到宿主机。
基于上述步骤，整合成如下的shell脚本：
#!/bin/bash#Get zookeeper imagezkimage=`docker images | grep zookeeper | awk {'print $1'}`if [ -n "$zkimage" ]then echo 'The zookeeper image is already existed.'else echo 'Pull the latest zookeeper image.' docker pull zookeeperfi#Create network for zookeeper containerszknet=`docker network ls | grep zknetwork | awk {'print $2'}`if [ -n "$zknet" ]then echo 'The zknetwork is already existed.'else echo 'Create zknetwork.' docker network create zknetworkfi#Start zookeeper clusterecho 'Start 3 zookeeper servers.'ZOO_SERVERS="server.1=zkServer1:2888:3888 server.2=zkServer2:2888:3888 server.3=zkServer3:2888:3888"docker run -d -e ZOO_SERVERS="$ZOO_SERVERS" -e ZOO_MY_ID=1 --name zkServer1 --net zknetwork -p 2181:2181 zookeeperdocker run -d -e ZOO_SERVERS="$ZOO_SERVERS" -e ZOO_MY_ID=2 --name zkServer2 --net zknetwork -p 2182:2181 zookeeperdocker run -d -e ZOO_SERVERS="$ZOO_SERVERS" -e ZOO_MY_ID=3 --name zkServer3 --net zknetwork -p 2183:2181 zookeeper 执行该shell脚本，便可启动一个新的zk集群。
root@hadoop985:~/docker/zookeeper-docker# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESbfc84ce7aa1d zookeeper "/docker-entrypoin..." 36 minutes ago Up 36 minutes 2888/tcp, 3888/tcp, 0.0.0.0:2183->2181/tcp zkServer318b6b1d9987c zookeeper "/docker-entrypoin..." 36 minutes ago Up 36 minutes 2888/tcp, 3888/tcp, 0.0.0.0:2182->2181/tcp zkServer20b6d1b69bb05 zookeeper "/docker-entrypoin..." 36 minutes ago Up 36 minutes 2888/tcp, 0.0.0.0:2181->2181/tcp, 3888/tcp zkServer1
本文来自网易云社区，经作者倪志风授权发布。
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