作者：Arthur 联系方式：ArthurHappy@qq.com 博客：https://www.jianshu.com/u/a8ffc2b3abf3
摘要：本文是基于docker 17.09.0搭建的hadoop 2.7.2 分布式跨主机集群，集群规模为一个master和两个salve，一共使用三台物理主机（两台或者多台物理机均可模拟），集群网络使用的是docker swarm搭建。
备注：中文社区中相关资料极少，相关资料请直接翻阅官方文档
转载请注明出处: https://www.jianshu.com/p/bf84d3fe77dd
环境介绍
环境要求
1. 操作系统：centos7
2. 物理机（或虚拟机）：两台或两台以上，本文使用三台
3. 网络：物理机需在同一子网中（最好给它分配固定ip），验证方式：互相ping是否能够ping通
4. 均安装了docker 17.X 版本（要求支持swarm）
本文环境介绍
1. 物理机
hostname ip
master 192.168.0.150
slave1 192.168.0.151
slave2 192.168.0.152
以下为具体配置过程
1. 下载hadoop镜像
master 下下载镜像。slave机子不需要下载，会在后续swarm网络中自动分发。
本文使用的hadoop镜像为kiwenlau/hadoop:1.0，相关介绍点此处。
[root@master ~]# docker pull kiwenlau/hadoop:1.0
2. 建立Swarm网络
在master上运行以下命令，建立以master为主节点的swarm网络。注意，ip改为你自己网络中master的ip。
[root@master ~]# docker swarm init --advertise-addr 192.168.1.150
运行之后会有如下信息提示
Swarm initialized: current node (ytxpz5xrzujbkmil0geiacepr) is now a manager.
To add a worker to this swarm, run the following command：
docker swarm join --token SWMTKN-1-3fbqppvsbpkg461lkeddkwjtng8ee0ufnuvfq1h8zzmhv3v54x-d4hdzdb997g6ljv4lga0r3xro 192.168.1.150:237
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
3. 子节点加入Swarm网络
进入slave1中，运行如下命令：
[root@slave1 ~]# docker swarm join --token SWMTKN-1-3fbqppvsbpkg461lkeddkwjtng8ee0ufnuvfq1h8zzmhv3v54x-d4hdzdb997g6ljv4lga0r3xro 192.168.1.150:237
同样进入slave2中，运行相同命令
[root@slave2 ~]# docker swarm join --token SWMTKN-1-3fbqppvsbpkg461lkeddkwjtng8ee0ufnuvfq1h8zzmhv3v54x-d4hdzdb997g6ljv4lga0r3xro 192.168.1.150:237
这样，节点slave1 slave2就加入了master的swarm网络了。其中运行的命令即为第二步中创建完网络提示的信息。
4. 创建一个专用网络
## 运行如下命令，查看现由网络。可以看到只有一个swarm网络ingress。这个是默认网络，我们一般不会直接使用
[root@master ~]# docker network ls
NETWORK ID NAME DRIVER SCOPE
8b78fc47d7fb bridge bridge local
9570aad7f0e0 docker_gwbridge bridge local
cf0d62f00408 host host local
xdelmzi55ifr ingress overlay swarm
90c51fe9392a none null local
## 创建一个专用网络
[root@master ~]# docker network create --opt encrypted --driver overlay --attachable hadoop
## 创建完成后可以看到多出了一个hadoop网络
[root@master ~]# docker network ls
8b78fc47d7fb bridge bridge local
9570aad7f0e0 docker_gwbridge bridge local
iv1irku3ohf7 hadoop overlay swarm
cf0d62f00408 host host local
xdelmzi55ifr ingress overlay swarm
90c51fe9392a none null local
5. 启动容器服务
[root@master ~]# docker service create -t --name hadoop-master --hostname hadoop-master --network hadoop --detach=false --replicas 1 --publish mode=host,target=8088,published=8088,protocol=tcp --publish mode=host,target=50070,published=50070,protocol=tcp kiwenlau/hadoop:1.0
[root@master ~]# docker service create -t --name hadoop-slave1 --hostname hadoop-slave1 --network hadoop --detach=false --replicas 1 kiwenlau/hadoop:1.0
[root@master ~]# docker service create -t --name hadoop-slave2 --hostname hadoop-slave2 --network hadoop --detach=false --replicas 1 kiwenlau/hadoop:1.0
## 启动成功后查看结果
[root@master ~]# docker service ls
ID NAME MODE REPLICAS IMAGE PORTS
p79vetbllisg hadoop-master replicated 1/1 kiwenlau/hadoop:1.0
8d9ll46cf7p2 hadoop-slave1 replicated 1/1 kiwenlau/hadoop:1.0
ghp3ffhnlbf3 hadoop-slave2 replicated 1/1 kiwenlau/hadoop:1.0
## 查看服务情况 可以观察到三个服务已经被分配到了不同的服务器上。这样容器就启动成功了。
[root@master ~]# docker service ps p79vetbllisg 8d9ll46cf7p2 ghp3ffhnlbf3
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
oml7l4xt0ay7 hadoop-slave2.1 kiwenlau/hadoop:1.0 slave2 Running Running 1 minutes ago
gva3i0ufqund hadoop-slave1.1 kiwenlau/hadoop:1.0 slave1 Running Running 1 minutes ago
1rn1f8jwv8gp hadoop-master.1 kiwenlau/hadoop:1.0 msater Running Running 1 minutes ago *:8088->8088/tcp,*:50070->50070/tcp
6. 启动hadoop
观察上一步我们发现， hadoop-master容器启动在master主机上。我们进入到master。
[root@master ~]# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
8282e646d559 kiwenlau/hadoop:1.0 "sh -c 'service ss..." 2 hours ago Up 2 hours 0.0.0.0:8088->8088/tcp, 0.0.0.0:50070->50070/tcp hadoop-master.1.1rn1f8jwv8gpmrb5i67ijysff
########## 进入容器
[root@master ~]# docker exec -it 8282e646d559 bash
########## 进入容器后的当前目录下可以看到已经有如下脚本
root@hadoop-master:~# ls
hdfs input run-wordcount.sh start-hadoop.sh
########## ping 下两个容器，看看是否能够ping通
root@hadoop-master:~# ping hadoop-slave1
root@hadoop-master:~# ping hadoop-slave2
########## 分别测试两个容器ssh是否正常，能够正常ssh登录则表明正常。 如果出现time out异常，请查看本文最后的异常分析。
root@hadoop-master:~# ssh hadoop-slave1
root@hadoop-slave1:~# exit
root@hadoop-master:~# ssh hadoop-slave2
root@hadoop-slave2:~# exit
########## 启动hadoop
root@hadoop-master:~# ./start-hadoop.sh
Starting namenodes on [hadoop-master]
hadoop-master: Warning: Permanently added 'hadoop-master,10.0.0.3' (ECDSA) to the list of known hosts.
hadoop-master: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-hadoop-master.out
hadoop-slave2: Warning: Permanently added 'hadoop-slave2,10.0.0.6' (ECDSA) to the list of known hosts.
hadoop-slave1: Warning: Permanently added 'hadoop-slave1,10.0.0.4' (ECDSA) to the list of known hosts.
hadoop-slave1: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-hadoop-slave1.out
hadoop-slave2: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-hadoop-slave2.out
Starting secondary namenodes [0.0.0.0]
0.0.0.0: Warning: Permanently added '0.0.0.0' (ECDSA) to the list of known hosts.
0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/logs/hadoop-root-secondarynamenode-hadoop-master.out
starting yarn daemons
starting resourcemanager, logging to /usr/local/hadoop/logs/yarn--resourcemanager-hadoop-master.out
hadoop-slave1: Warning: Permanently added 'hadoop-slave1,10.0.0.4' (ECDSA) to the list of known hosts.
hadoop-slave2: Warning: Permanently added 'hadoop-slave2,10.0.0.6' (ECDSA) to the list of known hosts.
hadoop-slave1: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-hadoop-slave1.out
hadoop-slave2: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-hadoop-slave2.out
########## 跑个word count测试下
root@hadoop-master:~# ./start-hadoop.sh
17/10/17 04:17:37 INFO client.RMProxy: Connecting to ResourceManager at hadoop-master/10.0.0.3:8032
....
input file1.txt:
Hello Hadoop
input file2.txt:
Hello Docker
wordcount output:
Docker 1
Hadoop 1
Hello 2
自此，使用docker的跨主机的hadoop集群搭建完成。
异常分析
1. swarm网络中的容器能够ping通但是无法互相ssh登录。
问题描述：笔者在搭建过程中碰到了这个问题，docker容器hadoop-master和hadoop-slave1,hadoop-slave2在一个swarm网络中，能够互相ping通，但是在ssh登录的时候出现connection time out异常，等了很久最后连接超时，也没有报其他问题。笔者在碰到这个问题的时候，找到的原因是物理主机slave1,slave2的防火墙没有关，直接截拦了对容器内部的ssh访问。
解决方案：
######进入slave1, slave2物理主机，都运行如下两条命令
# 关闭防火墙
[root@slave1 ~]# systemctl stop firewalld.service
# 关闭开机自启防火墙
[root@slave1 ~]# systemctl disable firewalld.service
