本篇只简单介绍安装步骤

 1. 角色分配

10.11.84.4 web-crawler--1.novalocal master/slave
10.11.84.5 web-crawler--2.novalocal slave
10.11.84.6 web-crawler--3.novalocal slave

2.安装目录 /usr/local/hadoop （HADOOP_HOME）

3,创建group hadoop

groupadd hadoop

4.创建用户hadoop

useradd -d /home/hadoop -g hadoop hadoop
chown -R hadoop:hadoop /usr/local/hadoop

5. 每台机器安装jdk（安装在相同的目录）

1)查看java 版本，可以看到jdk为openjdk，重庆网络维护，最好更换为sun jdk

[hadoop@hadoop2 ~]$ java -version
openjdk version "1.8.0_131"
OpenJDK Runtime Environment (build 1.8.0_131-b12)
OpenJDK 64-Bit Server VM (build 25.131-b12, mixed mode)
[hadoop@hadoop2 ~]$ rpm -qa | grep java
java-1.8.0-openjdk-headless-1.8.0.131-11.b12.el7.x86_64
javapackages-tools-3.4.1-11.el7.noarch
tzdata-java-2017b-1.el7.noarch
java-1.7.0-openjdk-headless-1.7.0.141-2.6.10.5.el7.x86_64
java-1.7.0-openjdk-1.7.0.141-2.6.10.5.el7.x86_64
java-1.8.0-openjdk-1.8.0.131-11.b12.el7.x86_64
python-javapackages-3.4.1-11.el7.noarch

2）卸载openjdk

rpm -qa | grep java | xargs yum -y remove

3）安装sunjdk

/usr/local 目录下解压jdk-8u181-linux-i586.tar.gz 并命名为jdk

配置环境变量如下

vim /etc/profile  末尾添加如下内容

export JAVA_HOME=/usr/local/jdk
export JRE_HOME=${JAVA_HOME}/jre
export PATH=${JAVA_HOME}/bin:${PATH}
export CLASSPATH=.:${JAVA_HOME}/lib:${JRE_HOME}/lib:${CLASSPATH} 

4）查看jdk是否安装成功

[root@hadoop2 local]# java -version
java version "1.8.0_151"
Java(TM) SE Runtime Environment (build 1.8.0_151-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode)

6. master 到 slave ssh 免密码登录

在每台机器hadoop用户下执行如下命令

[hadoop@hadoop1 ~]$ ssh-keygen -t rsa -P '' #一路直接回车
发送master 机器~/.ssh/id_rsa.pub 到所有slave节点
Scp id_rsa.pub hadoop@10.11.84.5:~
Scp id_rsa.pub hadoop@10.11.84.6:~
让后在每台slave节点hadoop 用户下执行如下命令
Cd ~/.ssh
Cat ../id_rsa.pub >> authorized_keys
Chmod 644 authorized_keys

7.关闭所有机器防火墙、selinux

1）centos 7 以下

防火墙
查看防火墙状态
service iptables status
临时关闭防火墙
service iptables stop
永久关闭防火墙
chkconfig iptables off
 selinux
setenforce 0 #临时关闭
永久关闭需要修改如下文件
vim /etc/selinux/config
将SELINUX=enforcing改为SELINUX=disabled

2)centos 7

firewall-cmd --reload #重启firewall
systemctl stop firewalld.service #停止firewall
systemctl disable firewalld.service #禁止firewall开机启动
firewall-cmd --state #查看默认防火墙状态（关闭后显示notrunning，开启后显示running）
selinux 同上

8.修改hadoop配置文件

Core-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl" rel="external nofollow" rel="external nofollow" rel="external nofollow" ?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>hadoop.tmp.dir</name>
<value>/home/hadoop/tmp</value>
<description>Abase for other temporary directories.</description>
</property>
<property>
<name>fs.default.name</name>
<value>hdfs://web-crawler--1.novalocal:9000</value>
</property>
</configuration>
hadoop-env.sh 添加java_home
 export JAVA_HOME=/usr/local/jdk
hdfs-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl" rel="external nofollow" rel="external nofollow" rel="external nofollow" ?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
<property>
<name>dfs.name.dir</name>
<value>/home/hadoop/name</value>
</property>
<property>
<name>dfs.data.dir</name>
<value>/home/hadoop/data</value>
</property>
</configuration>
mapred-site.xml
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl" rel="external nofollow" rel="external nofollow" rel="external nofollow" ?>
<!-- Put site-specific property overrides in this file. -->
<configuration>
 <property>
    <name>mapred.job.tracker</name>
    <value>http://web-crawler--1.novalocal:9001</value>;;;
  </property>
<property>
    <name>mapred.system.dir</name>
    <value>/home/hadoop/mapred/system</value>
  </property>
<property>
    <name>mapred.local.dir</name>
    <value>/home/hadoop/mapred/local</value>
  </property>
</configuration>

5)masters

web-crawler--1.novalocal

6)slaves

web-crawler--1.novalocal
web-crawler--2.novalocal 
web-crawler--3.novalocal