hadoop的client搭建-即集群外主机访问hadoop

1增加主机映射(与namenode的映射一样)：

增加最后一行

 [root@localhost ~]# su - root
1 [root@localhost ~]# vi /etc/hosts
 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
 ::         localhost localhost.localdomain localhost6 localhost6.localdomain6
 192.168.48.129    hadoop-master
 [root@localhost ~]# 

2新建用户hadoop

建立hadoop用户组

新建用户，useradd -d /usr/hadoop -g hadoop -m hadoop （新建用户hadoop指定用户主目录/usr/hadoop 及所属组hadoop）

passwd hadoop 设置hadoop密码（这里设置密码为hadoop）

[root@localhost ~]# groupadd hadoop  
[root@localhost ~]# useradd -d /usr/hadoop -g hadoop -m hadoop 
[root@localhost ~]# passwd hadoop

3配置jdk环境

本次安装的是hadoop-2.7.5，需要JDK 7以上版本。若已安装可跳过。

JDK安装可参考：https://www.cnblogs.com/shihaiming/p/5809553.html

或者直接拷贝master上的JDK文件更有利于保持版本的一致性。

[root@localhost java]# su - root
[root@localhost java]# mkdir -p /usr/java
[root@localhost java]# scp -r hadoop@hadoop-master:/usr/java/jdk1.7.0_79 /usr/java
[root@localhost java]# ll
total 12
drwxr-xr-x. 8 root root 4096 Feb 13 01:34 default
drwxr-xr-x. 8 root root 4096 Feb 13 01:34 jdk1.7.0_79
drwxr-xr-x. 8 root root 4096 Feb 13 01:34 latest

设置Java及hadoop环境变量

确保/usr/java/jdk1.7.0.79存在

su - root

vi /etc/profile

确保/usr/java/jdk1.7.0.79存在

 unset i
 unset -f pathmunge
 JAVA_HOME=/usr/java/jdk1..0_79
 CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
 PATH=/usr/hadoop/hadoop-2.7./bin:$JAVA_HOME/bin:$PATH

设置生效（重要）

[root@localhost ~]# source /etc/profile
[root@localhost ~]# 

JDK安装后确认：

[hadoop@localhost ~]$ java -version
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
[hadoop@localhost ~]$ 

4设置hadoop的环境变量

拷贝namenode上已配置好的hadoop目录到当前主机

[root@localhost ~]# su - hadoop
Last login: Sat Feb  :: CST  on pts/
[hadoop@localhost ~]$ pwd
/usr/hadoop
[hadoop@localhost ~]$ scp -r hadoop@hadoop-master:/usr/hadoop/hadoop-2.7.5 .
The authenticity of host 'hadoop-master (192.168.48.129)' can't be established.
ECDSA key fingerprint is 1e:cd:d1:3d:b0:5b:62:45:a3:63:df:c7:7a:0f:b8:7c.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'hadoop-master,192.168.48.129' (ECDSA) to the list of known hosts.
hadoop@hadoop-master's password:

[hadoop@localhost ~]$ ll
total
drwxr-xr-x   hadoop hadoop    Feb  : Desktop
drwxr-xr-x   hadoop hadoop    Feb  : Documents
drwxr-xr-x   hadoop hadoop    Feb  : Downloads
drwxr-xr-x  hadoop hadoop  Feb  : hadoop-2.7.
drwxr-xr-x   hadoop hadoop    Feb  : Music
drwxr-xr-x   hadoop hadoop    Feb  : Pictures
drwxr-xr-x   hadoop hadoop    Feb  : Public
drwxr-xr-x   hadoop hadoop    Feb  : Templates
drwxr-xr-x   hadoop hadoop    Feb  : Videos
[hadoop@localhost ~]$ 

到此，Hadoop的客户端安装就算完成了，接下来就可以使用了。

执行hadoop命令结果如下，

[hadoop@localhost ~]$ hadoop
Usage: hadoop [--config confdir] [COMMAND | CLASSNAME]
  CLASSNAME            run the class named CLASSNAME
 or
  where COMMAND is one of:
  fs                   run a generic filesystem user client
  version              print the version
  jar <jar>            run a jar file
                       note: please use "yarn jar" to launch
                             YARN applications, not this command.
  checknative [-a|-h]  check native hadoop and compression libraries availability
  distcp <srcurl> <desturl> copy file or directories recursively
  archive -archiveName NAME -p <parent path> <src>* <dest> create a hadoop archive
  classpath            prints the class path needed to get the
  credential           interact with credential providers
                       Hadoop jar and the required libraries
  daemonlog            get/set the log level for each daemon
  trace                view and modify Hadoop tracing settings

Most commands print help when invoked w/o parameters.
[hadoop@localhost ~]$

5.使用hadoop

创建本地文件

[hadoop@localhost ~]$ hdfs dfs -ls
Found 1 items
drwxr-xr-x   - hadoop supergroup          0 2018-02-22 23:41 output
[hadoop@localhost ~]$ vi my-local.txt
hello boy!
yehyeh

上传本地文件至集群

[hadoop@localhost ~]$ hdfs dfs -mkdir upload
[hadoop@localhost ~]$ hdfs dfs -ls upload
[hadoop@localhost ~]$ hdfs dfs -ls
Found  items
drwxr-xr-x   - hadoop supergroup           -- : output
drwxr-xr-x   - hadoop supergroup           -- : upload
[hadoop@localhost ~]$ hdfs dfs -ls upload
[hadoop@localhost ~]$ hdfs dfs -put my-local.txt upload
[hadoop@localhost ~]$ hdfs dfs -ls upload
Found 1 items
-rw-r--r--   3 hadoop supergroup         18 2018-02-23 22:45 upload/my-local.txt
[hadoop@localhost ~]$ hdfs dfs -cat upload/my-local.txt
hello boy!
yehyeh
[hadoop@localhost ~]$ 

ps:注意本地java版本与master拷贝过来的文件中/etc/hadoop-env.sh配置的JAVA_HOME是否要保持一致没有验证过，本文是保持一致的