Docker创建的集群下使用ansible部署hadoop

摘要：创建的集群下使用部署基础环境关键词集群架构集群包含台虚拟主机，采用创建容器的方式创建，无需创建多台虚拟机，简单方便。

MBP, Palallels Desktop, Centos7

docker, ansible, hadoop

集群包含4台“虚拟主机”，采用Docker创建容器的方式创建，无需创建多台虚拟机，简单方便。

登录到Centos 7寄主机中安装docker

[root@centos-linux ~]# yum -y install docker.x86_64

[root@centos-linux ~]# systemctl start docker

国内使用docker.io拉取镜像的时候非常慢，所以找了镜像仓库进行拉取。
本次用到的镜像仓库是http://hub.daocloud.io, 在搜索栏中输入centos并搜索

在检索到的镜像详情右侧给出了pull的命令，直接运行即可。

[root@centos-linux ~]# docker pull daocloud.io/library/centos:latest

拉取完成之后可以看到

[root@centos-linux ~]# docker images
REPOSITORY                   TAG                 IMAGE ID            CREATED             SIZE
daocloud.io/library/centos   latest              328edcd84f1b        3 weeks ago         192.5 MB

按照集群的架构，创建容器时需要设置固定IP，所以先要在docker下创建固定IP的网络组

[root@centos-linux ~]# docker network create --subnet=172.18.0.0/16 netgroup

docker的网络组创建完成之后就可以创建固定IP的容器了

[root@centos-linux ~]# docker run -d --privileged -ti -v /sys/fs/cgroup:/sys/fs/cgroup --name cluster-master -h cluster-master --net netgroup --ip 172.18.0.2 daocloud.io/library/centos /usr/sbin/init
[root@centos-linux ~]# docker run -d --privileged -ti -v /sys/fs/cgroup:/sys/fs/cgroup --name cluster-slave1 -h cluster-slave1 --net netgroup --ip 172.18.0.3 daocloud.io/library/centos /usr/sbin/init
[root@centos-linux ~]# docker run -d --privileged -ti -v /sys/fs/cgroup:/sys/fs/cgroup --name cluster-slave2 -h cluster-slave2 --net netgroup --ip 172.18.0.4 daocloud.io/library/centos /usr/sbin/init
[root@centos-linux ~]# docker run -d --privileged -ti -v /sys/fs/cgroup:/sys/fs/cgroup --name cluster-slave3 -h cluster-slave3 --net netgroup --ip 172.18.0.5 daocloud.io/library/centos /usr/sbin/init

在Centos7下使用简单方式创建容器后遇到sshd启动失败的问题，所以需要添加参数--privileged和-v /sys/fs/cgroup:/sys/fs/cgroup，并在启动的时候运行/usr/sbin/init。

创建的centos容器中并没有预装ssh服务，需要登录到所有容器中手动安装。

[root@centos-linux ~]# docker ps -a
CONTAINER ID        IMAGE                        COMMAND             CREATED             STATUS              PORTS               NAMES
328913df0d52        daocloud.io/library/centos   "/usr/sbin/init"    1 hours ago        Up 1 hours                             cluster-slave3
83361d4bf079        daocloud.io/library/centos   "/usr/sbin/init"    1 hours ago        Up 1 hours                             cluster-slave2
35d1e5732340        daocloud.io/library/centos   "/usr/sbin/init"    1 hours ago        Up 1 hours                             cluster-slave1
37fbcc24b0e3        daocloud.io/library/centos   "/usr/sbin/init"    1 hours ago        Up 1 hours                             cluster-master

[root@centos-linux ~]# docker exec -it 37fbcc24b0e3 /bin/bash

[root@cluster-master /]# yum -y install openssh openssh-server openssh-clients

[root@cluster-master /]# systemctl start sshd

master设置ssh登录自动添加kown_hosts
vi编辑/etc/ssh/ssh_config配置文件
设置StrictHostKeyChecking为no

/etc/hosts文件在容器启动时被重写，直接修改内容在容器重启后不能保留，为了让容器在重启之后获取集群hosts，使用了一种启动容器后重写hosts的方法。
需要在~/.bashrc中追加以下指令

:>/etc/hosts
cat >>/etc/hosts<
运行source ~/.bashrc使之生效  
这时可以看到/etc/hosts文件已经被改为需要的内容
[root@cluster-master /]# cat /etc/hosts
127.0.0.1   localhost
172.18.0.2  cluster-master
172.18.0.3  cluster-slave1
172.18.0.4  cluster-slave2
172.18.0.5  cluster-slave3
cluster-master公钥分发
在master机上执行ssh-keygen -t rsa并一路回车，完成之后会生成~/.ssh目录，目录下有id_rsa（私钥文件）和id_rsa.pub（公钥文件），再将id_rsa.pub重定向到文件authorized_keys
[root@cluster-master /]# cd ~/.ssh
[root@cluster-master /]# cat id_rsa.pub>authorized_keys
文件生成之后用scp将公钥文件分发到集群slave主机
[root@cluster-master /]# ssh root@cluster-slave1 "mkdir ~/.ssh"
[root@cluster-master /]# scp ~/.ssh/authorized_keys root@cluster-slave1:~/.ssh
[root@cluster-master /]# ssh root@cluster-slave2 "mkdir ~/.ssh"
[root@cluster-master /]# scp ~/.ssh/authorized_keys root@cluster-slave2:~/.ssh
[root@cluster-master /]# ssh root@cluster-slave3 "mkdir ~/.ssh"
[root@cluster-master /]# scp ~/.ssh/authorized_keys root@cluster-slave3:~/.ssh
分发完成之后测试是否已经可以免输入密码登录。另外本次实验使用到了root用户，如果在其他用户下使用免密码登录，需要确保用户对~/.ssh/authorized_keys文件有可操作权限。
Ansible
源码安装ansible
使用git将文件安装在cluster-master的/opt目录下，因为无需agent，所以安装在一台主控机上即可管理集群。容器中的centos没有预装git，在安装之前需要事先安装git:
[root@cluster-master /]# yum -y install git
在/opt下执行
[root@cluster-master opt]# git clone git://github.com/ansible/ansible.git --recursive
在执行ansible的env-setup之前需要安装一些容器中没有预装的软件包
[root@cluster-master opt]# yum -y install python-setuptools
[root@cluster-master opt]# easy_install pip
[root@cluster-master opt]# pip install paramiko PyYAML Jinja2 httplib2 six
进入ansible目录，执行安装脚本
[root@cluster-master opt]# cd ./ansible
[root@cluster-master ansible]# source ./hacking/env-setup
配置ansible hosts
创建/etc/ansible/hosts文件，并将cluster内的主机按组的方式写入该文件
[cluster]
cluster-master
cluster-slave1
cluster-slave2
cluster-slave3

[master]
cluster-master

[slaves]
cluster-slave1
cluster-slave2
cluster-slave3

Hadoop
在集群中安装openjdk
使用ansible在在集群中安装openjdk
[root@cluster-master ansible]# ansible cluster -m yum -a "name=java-1.8.0-openjdk,java-1.8.0-openjdk-devel state=latest"
在cluster-master上安装hadoop
将hadoop安装包下载至/opt目录下
[root@cluster-master opt]# wget http://mirrors.tuna.tsinghua.edu.cn/apache/hadoop/common/hadoop-2.7.4/hadoop-2.7.4.tar.gz
下载完成之后解压安装包，并创建链接文件
[root@cluster-master opt]# tar -xzvf hadoop-2.7.4.tar.gz
[root@cluster-master opt]# ln -s hadoop-2.7.4 hadoop
设置java和hadoop环境变量(.bashrc)
# java
export JAVA_HOME=/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.141-1.b16.el7_3.x86_64
export PATH=$HADOOP_HOME/bin:$PATH
# hadoop
export HADOOP_HOME=/opt/hadoop
export PATH=$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PATH
修改slaves文件
[root@cluster-master opt]# vi /opt/hadoop/etc/hadoop/slaves
cluster-slave1
cluster-slave2
cluster-slave3
修改hadoop运行所需配置文件
core-site.xml

    
        hadoop.tmp.dir
        /home/hadoop/tmp
        A base for other temporary directories.
    
    
    
        fs.default.name
       hdfs://cluster-master:9000
    

hdfs-site.xml

    
        dfs.replication
        3
    

mapred-site.xml

    
        mapred.job.tracker
        http://cluster-master:9001
    

yarn-site.xml

    
        yarn.nodemanager.aux-services
        mapreduce_shuffle
    
    
        yarn.resourcemanager.address
        cluster-master:18040
    

打包hadoop文件
将hadoop链接文件和hadoop-2.7.4打包成一个文件方便ansible分发到slave主机
[root@cluster-master opt]# tar -cvf hadoop-dis.tar hadoop hadoop-2.7.4
使用ansible-playbook分发.bashrc和hadoop-dis.tar至slave主机
---
- hosts: cluster
  tasks:
    - name: copy .bashrc to slaves
      copy: src=~/.bashrc dest=~/
      notify:
        - exec source
    - name: mkdir /home/hadoop/tmp
      shell: mkdir -p /home/hadoop/tmp
      
    - name: copy hadoop-dis.tar to slaves
      unarchive: src=/opt/hadoop-dis.tar dest=/opt


  handlers:
    - name: exec source
      shell: source ~/.bashrc
将以上yaml保存为hadoop-dis.yaml，并执行
[root@cluster-master opt]# ansible-playbook hadoop-dis.yaml
hadoop-dis.tar会自动解压到slave主机的/opt目录下。
格式化namenode
[root@cluster-master opt]# hadoop namenode -format
启动hadoop集群
到这一步已经可以开始hadoop之旅了，启动比较简单，在$HADOOP_HOME/sbin下有几个启动和停止的脚本如下：
[root@cluster-master opt]# cd $HADOOP_HOME/sbin
[root@cluster-master sbin]# ls -l
total 120
-rwxr-xr-x. 1 20415 101 2752 Aug  1 00:35 distribute-exclude.sh
-rwxr-xr-x. 1 20415 101 6452 Aug  1 00:35 hadoop-daemon.sh
-rwxr-xr-x. 1 20415 101 1360 Aug  1 00:35 hadoop-daemons.sh
-rwxr-xr-x. 1 20415 101 1640 Aug  1 00:35 hdfs-config.cmd
-rwxr-xr-x. 1 20415 101 1427 Aug  1 00:35 hdfs-config.sh
-rwxr-xr-x. 1 20415 101 2291 Aug  1 00:35 httpfs.sh
-rwxr-xr-x. 1 20415 101 3128 Aug  1 00:35 kms.sh
-rwxr-xr-x. 1 20415 101 4080 Aug  1 00:35 mr-jobhistory-daemon.sh
-rwxr-xr-x. 1 20415 101 1648 Aug  1 00:35 refresh-namenodes.sh
-rwxr-xr-x. 1 20415 101 2145 Aug  1 00:35 slaves.sh
-rwxr-xr-x. 1 20415 101 1779 Aug  1 00:35 start-all.cmd
-rwxr-xr-x. 1 20415 101 1471 Aug  1 00:35 start-all.sh
-rwxr-xr-x. 1 20415 101 1128 Aug  1 00:35 start-balancer.sh
-rwxr-xr-x. 1 20415 101 1401 Aug  1 00:35 start-dfs.cmd
-rwxr-xr-x. 1 20415 101 3734 Aug  1 00:35 start-dfs.sh
-rwxr-xr-x. 1 20415 101 1357 Aug  1 00:35 start-secure-dns.sh
-rwxr-xr-x. 1 20415 101 1571 Aug  1 00:35 start-yarn.cmd
-rwxr-xr-x. 1 20415 101 1347 Aug  1 00:35 start-yarn.sh
-rwxr-xr-x. 1 20415 101 1770 Aug  1 00:35 stop-all.cmd
-rwxr-xr-x. 1 20415 101 1462 Aug  1 00:35 stop-all.sh
-rwxr-xr-x. 1 20415 101 1179 Aug  1 00:35 stop-balancer.sh
-rwxr-xr-x. 1 20415 101 1455 Aug  1 00:35 stop-dfs.cmd
-rwxr-xr-x. 1 20415 101 3206 Aug  1 00:35 stop-dfs.sh
-rwxr-xr-x. 1 20415 101 1340 Aug  1 00:35 stop-secure-dns.sh
-rwxr-xr-x. 1 20415 101 1642 Aug  1 00:35 stop-yarn.cmd
-rwxr-xr-x. 1 20415 101 1340 Aug  1 00:35 stop-yarn.sh
-rwxr-xr-x. 1 20415 101 4295 Aug  1 00:35 yarn-daemon.sh
-rwxr-xr-x. 1 20415 101 1353 Aug  1 00:35 yarn-daemons.sh
主要使用HDFS，启动start-dfs.sh即可
[root@cluster-master sbin]# ./start-dfs.sh
Starting namenodes on [cluster-master]
cluster-master: starting namenode, logging to /opt/hadoop-2.7.4/logs/hadoop-root-namenode-cluster-master.out
cluster-slave1: starting datanode, logging to /opt/hadoop-2.7.4/logs/hadoop-root-datanode-cluster-slave1.out
cluster-slave3: starting datanode, logging to /opt/hadoop-2.7.4/logs/hadoop-root-datanode-cluster-slave3.out
cluster-slave2: starting datanode, logging to /opt/hadoop-2.7.4/logs/hadoop-root-datanode-cluster-slave2.out
Starting secondary namenodes [0.0.0.0]
0.0.0.0: starting secondarynamenode, logging to /opt/hadoop-2.7.4/logs/hadoop-root-secondarynamenode-cluster-master.out
启动完成之后会在master和slave看到以下进程
cluster-master
[root@cluster-master sbin]# jps
2484 SecondaryNameNode
2648 Jps
2315 NameNode
cluster-slave
[root@cluster-slave1 logs]# jps
27502 DataNode
27583 Jps
体验hadoop
在master端上传文件试试
[root@cluster-master sbin]# hadoop dfs -put start-dfs.sh /
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

[root@cluster-master sbin]# hadoop dfs -ls /
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

Found 1 items
-rw-r--r--   3 root supergroup       3734 2017-08-26 10:57 /start-dfs.sh
总结
docker下部署hadoop确实比较奇葩，但是对于个人学习来说确是十分方便，不用在虚拟机里复制多套环境，也简化了网络配置的步骤，加上ansible的使用使得集群的管理更加高效。