文章/答案/技术大牛

发布

社区首页 >专栏 >Hadoop的安装和使用

Hadoop的安装和使用

foochane

发布于 2019-05-23 07:40:07

1.3K00

代码可运行

文章被收录于专栏：foochanefoochane

运行总次数：0

代码可运行

1 创建Hadoop用户

1.1 创建新用户

用户名为hadoop，使用/bin/bash作为shell

$ sudo useradd -m hadoop -s /bin/bash

1.2 修改密码

$ sudo passwd hadoop
Enter new UNIX password: 
Retype new UNIX password: 
passwd: password updated successfully

1.2 为hadoop用户添加管理员权限

$ sudo adduser hadoop sudo
Adding user `hadoop' to group `sudo' ...
Adding user hadoop to group sudo
Done.

2 安装java环境

2.1 安装

$ sudo apt-get install default-jre default-jdk

2.2 配置环境变量

$ vim ~/.bashrc

后面加入export JAVA_HOME=/usr/lib/jvm/default-java 然后使环境变量生效：

$ source ~/.bashrc

2.3 测试java是否安装成功

$ echo $JAVA_HOME
/usr/lib/jvm/default-java
$ java -version
openjdk version "1.8.0_191"
OpenJDK Runtime Environment (build 1.8.0_191-8u191-b12-0ubuntu0.16.04.1-b12)
OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)

3 设置SSH

SSH是Secure Shell的缩写，SSH由客户端和服务端构成，服务端是一个守护进程，在后台运行并相应来自客户端的请求，客户端包含远程复制scp、安全文件传输sftp，远程登录slogin等运用程序。

Ubuntu已经默认安装了SSH客户端，还需要安装SSH服务端。

【注意】：Hadoop并没有提供SSH密码登录的形式，所以需要将所有机器配置为无密码登录。

3.1 安装SSH服务端

$ sudo apt-get install openssh-server

3.2 登录localhost

$ ssh localhost
The authenticity of host 'localhost (127.0.0.1)' can't be established.
ECDSA key fingerprint is SHA256:MCT7ubGt3sPlkvS9v//KhAoa7vBO+EVPJN/JXenC8XM.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'localhost' (ECDSA) to the list of known hosts.
hadoop@localhost's password: 
Welcome to Ubuntu 16.04.3 LTS (GNU/Linux 4.10.0-42-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

243 packages can be updated.
11 updates are security updates.

之后会在~/文件夹下发现一个.ssh文件

3.3 设置为无密码登录

$ cd ~/.ssh/
$ ssh-keygen -t rsa  #出现提示直接按enter
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:FaavA0T6j8XH0clbVu0pq5hkad7kADUBibL/76I2U00 hadoop@ubuntu
The key's randomart image is:
+---[RSA 2048]----+
|      o.o.+     o|
|   . + . = + . ..|
|    + . o + + o..|
|   . o o E . = ..|
|    . o S = . o  |
|     . * X . .   |
|      + O B .    |
|     + o = +     |
|    ..+ +o       |
+----[SHA256]-----+
$ cat ./id_rsa.pub >> ./authorized_keys  #加入授权

此时就直接使用$ ssh localhost，无密码登录了。

4 安装Hadoop

Hadoop的安装包括3中模式：（1）单机模式：只在一台机器上运行，存储采用本地文件系统，没有采用分布式文件系统HDFS。（2）伪分布式模式：存储采用分布式文件系统HDFS，但是HDFS的节点和数据节点都在同一节点。（2）分布式模式：存储采用分布式文件系统HDFS，而且HDFS的节点和数据节点位于不同机器上。

Hadoop的下载：http://mirrors.cnnic.cn/apache/hadoop/common

4.1 单机模式配置

下载安装包后解压即可使用：

$ sudo tar -zxvf hadoop-2.7.1.tar.gz -C /usr/local
$ cd /usr/local/
$ sudo mv ./hadoop-2.7.1/ ./hadoop      # 将文件夹名改为hadoop
$ sudo chown -R hadoop ./hadoop       # 修改文件权限

查看Hadoop版本信息：

$ cd /usr/local/hadoop/bin
$ ./hadoop version
Hadoop 2.7.1
Subversion https://git-wip-us.apache.org/repos/asf/hadoop.git -r 15ecc87ccf4a0228f35af08fc56de536e6ce657a
Compiled by jenkins on 2015-06-29T06:04Z
Compiled with protoc 2.5.0
From source with checksum fc0a1a23fc1868e4d5ee7fa2b28a58a
This command was run using /usr/local/hadoop/share/hadoop/common/hadoop-common-2.7.1.jar

Hadoop附带了很多例子，运行如下命令可以查看：

$ ./hadoop jar ../share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.1.jar
An example program must be given as the first argument.
Valid program names are:
  aggregatewordcount: An Aggregate based map/reduce program that counts the words in the input files.
  aggregatewordhist: An Aggregate based map/reduce program that computes the histogram of the words in the input files.
  bbp: A map/reduce program that uses Bailey-Borwein-Plouffe to compute exact digits of Pi.
  dbcount: An example job that count the pageview counts from a database.
  distbbp: A map/reduce program that uses a BBP-type formula to compute exact bits of Pi.
  grep: A map/reduce program that counts the matches of a regex in the input.
  join: A job that effects a join over sorted, equally partitioned datasets
  multifilewc: A job that counts words from several files.
  pentomino: A map/reduce tile laying program to find solutions to pentomino problems.
  pi: A map/reduce program that estimates Pi using a quasi-Monte Carlo method.
  randomtextwriter: A map/reduce program that writes 10GB of random textual data per node.
  randomwriter: A map/reduce program that writes 10GB of random data per node.
  secondarysort: An example defining a secondary sort to the reduce.
  sort: A map/reduce program that sorts the data written by the random writer.
  sudoku: A sudoku solver.
  teragen: Generate data for the terasort
  terasort: Run the terasort
  teravalidate: Checking results of terasort
  wordcount: A map/reduce program that counts the words in the input files.
  wordmean: A map/reduce program that counts the average length of the words in the input files.
  wordmedian: A map/reduce program that counts the median length of the words in the input files.
  wordstandarddeviation: A map/reduce program that counts the standard deviation of the length of the words in the input files.

下面运行grep程序

$ cd /usr/local/hadoop
$ mkdir input
$ cp ./etc/hadoop/*.xml ./input   # 将配置文件复制到input目录下
$ ./bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-*.jar grep ./input ./output 'dfs[a-z.]+'
$ cat ./output/*          # 查看运行结果
1       dfsadmin

运行成功后，可以看到grep程序将input文件夹作为输入，从文件夹中筛选出所有符合正则表达式dfs[a-z]+的单词，并把单词出现的次数的统计结果输出到/usr/local/hadoop/output文件夹下。

【注意】：如果再次运行上述命令，会报错，因为Hadoop默认不会覆盖output输出结果的文件夹，所有需要先删除output文件夹才能再次运行。

4.2 伪分布式模式配置

在单个节点（一台机器上）以伪分布式的方式运行。

4.2.1 修改配置文件

需要修改/usr/local/hadoop/etc/hadoop/文件夹下的core-site.xml和hdfs-site.xml 文件。

core-site.xml文件: 将

<configuration>
</configuration>

修改为：

<configuration>
    <property>
        <name>hadoop.tmp.dir</name>
        <value>file:/usr/local/hadoop/tmp</value>
        <description>Abase for other temporary directories.</description>
    </property>
    <property>
        <name>fs.defaultFS</name>
        <value>hdfs://localhost:9000</value>
    </property>
</configuration>

hadoop.tmp.dir用于保存临时文件，如果没有配置这个参数，则默认使用的临时目录为/tmp/hadoo-hadoop，这个目录在Hadoop重启后会被系统清理掉。
fs.defaultFS用于指定HDFS的访问地址。

hdfs-site.xml文件修改如下：

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
    <property>
        <name>dfs.namenode.name.dir</name>
        <value>file:/usr/local/hadoop/tmp/dfs/name</value>
    </property>
    <property>
        <name>dfs.datanode.data.dir</name>
        <value>file:/usr/local/hadoop/tmp/dfs/data</value>
    </property>
</configuration>

dfs.replicaion：指定副本数量，在分布式文件系统中，数据通常会被冗余的存储多份，以保证可靠性和安全性，但是这里用的是伪分布式模式，节点只有一个，也有就只有一个副本。
dfs.namenode.name.di：设定名称节点元数据的保存目录
dfs.datanode.data.dir：设定数据节点的数据保存目录

这里，名称节点和数据节点必须设定。

【注意】：Hadoop的运行方式是由配置文件决定的，如果想从伪分布式模式切换回单机模式，只需删除core-site.xml文件中的配置项即可

4.2.2 执行名称节点格式化

执行如下命令：

$ cd /usr/local/hadoop
$ ./bin/hdfs namenode -format

【错误】：出现Exiting with status 1表示出现错误

19/01/11 18:38:02 ERROR namenode.NameNode: Failed to start namenode.
java.lang.IllegalArgumentException: URI has an authority component
    at java.io.File.<init>(File.java:423)
    at org.apache.hadoop.hdfs.server.namenode.NNStorage.getStorageDirectory(NNStorage.java:329)
    at org.apache.hadoop.hdfs.server.namenode.FSEditLog.initJournals(FSEditLog.java:276)
    at org.apache.hadoop.hdfs.server.namenode.FSEditLog.initJournalsForWrite(FSEditLog.java:247)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.format(NameNode.java:985)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1429)
    at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1554)
19/01/11 18:38:02 INFO util.ExitUtil: Exiting with status 1
19/01/11 18:38:02 INFO namenode.NameNode: SHUTDOWN_MSG: 
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at ubuntu/127.0.1.1
************************************************************/

【解决】：检查hdfs-site.xml的配置

如果出现/usr/local/hadoop/tmp/dfs/name has been successfully formatted.和 Exiting with status 0，表示格式化成功。

19/01/11 18:46:35 INFO common.Storage: Storage directory /usr/local/hadoop/tmp/dfs/name has been successfully formatted.
19/01/11 18:46:36 INFO namenode.NNStorageRetentionManager: Going to retain 1 images with txid >= 0
19/01/11 18:46:36 INFO util.ExitUtil: Exiting with status 0

4.2.3 启动Hadoop

$ cd /usr/local/hadoop
$ ./sbin/start-dfs.sh

【错误】：

Starting namenodes on [localhost]
localhost: Error: JAVA_HOME is not set and could not be found.
localhost: Error: JAVA_HOME is not set and could not be found.
Starting secondary namenodes [0.0.0.0]

【解决】：

$ echo $JAVA_HOME
/usr/lib/jvm/default-java

查看后发现JAVA_HOME路径已经设置，那就只能将/hadoop/etc/hadoop/hadoop-env.sh文件的JAVA_HOME改为绝对路径了。将export JAVA_HOME=$JAVA_HOME改为 export JAVA_HOME=/usr/lib/jvm/default-java

用jps命令查看Hadoop是否启动成功，如果出现DataNode、NameNode、SecondaryNameNode的进程说明启动成功。

$ jps
4821 Jps
4459 DataNode
4348 NameNode
4622 SecondaryNameNode

如果还要问题，重复如下命令：

$ ./sbin/stop-dfs.sh   # 关闭
$ rm -r ./tmp     # 删除 tmp 文件，注意这会删除 HDFS中原有的所有数据
$ ./bin/hdfs namenode -format   # 重新格式化名称节点
$ ./sbin/start-dfs.sh  # 重启

4.2.4 使用浏览器查看HDFS信息

在浏览器中打开链接：http://localhost:50070/dfshealth.html#tab-overview 即可查看：

4.2.5 运行Hadoop伪分布式实例

$ cd /usr/local/hadoop
$ ./bin/hdfs dfs -mkdir -p /user/hadoop # 在HDFS中创建用户目录
$ ./bin/hdfs dfs -mkdir input  #在HDFS中创建hadoop用户对应的input目录
$ ./bin/hdfs dfs -put ./etc/hadoop/*.xml input  #把本地文件复制到HDFS中
$ ./bin/hdfs dfs -ls input #查看文件列表
Found 8 items
-rw-r--r--   1 hadoop supergroup       4436 2019-01-11 19:35 input/capacity-scheduler.xml
-rw-r--r--   1 hadoop supergroup       1075 2019-01-11 19:35 input/core-site.xml
-rw-r--r--   1 hadoop supergroup       9683 2019-01-11 19:35 input/hadoop-policy.xml
-rw-r--r--   1 hadoop supergroup       1130 2019-01-11 19:35 input/hdfs-site.xml
-rw-r--r--   1 hadoop supergroup        620 2019-01-11 19:35 input/httpfs-site.xml
-rw-r--r--   1 hadoop supergroup       3518 2019-01-11 19:35 input/kms-acls.xml
-rw-r--r--   1 hadoop supergroup       5511 2019-01-11 19:35 input/kms-site.xml
-rw-r--r--   1 hadoop supergroup        690 2019-01-11 19:35 input/yarn-site.xml
$ ./bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-*.jar grep input output 'dfs[a-z.]+'
....
$ ./bin/hdfs dfs -cat output/* #查看运行结果
1   dfsadmin
1   dfs.replication
1   dfs.namenode.name.dir
1   dfs.datanode.data.dir

再次运行需要删除output文件夹

$ ./bin/hdfs dfs -rm -r output    # 删除 output 文件夹

4.2.6 关闭Hadoop

使用命令：

./sbin/stop-dfs.sh

下次启动时不需要再执行节点格式化命令（否则会报错），只需要直接运行start-dfs.sh命令即可。

5 总结

hadoop的安装步骤： 1 创建Hadoop用户 2 安装java环境 3 设置SSH 4 修改配置文件修改/usr/local/hadoop/etc/hadoop/文件夹下的core-site.xml和hdfs-site.xml 文件 5 相关命令

$ cd /usr/local/hadoop
$ ./bin/hdfs namenode -format #格式化名称节点 （这个命令只需只需一次）
$ ./sbin/start-dfs.sh  #启动Hadoop
$ jps #查看Hadoop是否成功启动
$ ./sbin/stop-dfs.sh   # 关闭Hadoop
$ rm -r ./tmp     # 删除 tmp 文件，注意这会删除 HDFS中原有的所有数据
$ ./sbin/start-dfs.sh  # 重启