安装前准备

操作系统准备

本次安装采用的操作系统是Ubuntu 20.04。

更新一下软件包列表。

sudo apt-get update

安装Java 8+

使用命令安装Java 8。

sudo apt-get install -y openjdk-8-jdk

配置环境变量。

vi ~/.bashrc

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

让环境变量生效。

source ~/.bashrc

下载Hadoop安装包

从Hadoop官网Apache Hadoop下载安装包软件。

或者直接通过命令下载。

wget https://dlcdn.apache.org/hadoop/common/hadoop-3.3.4/hadoop-3.3.4.tar.gz

伪分布式安装

伪分布式是在一个节点上运行多个进程来模拟集群。

配置免密登录

Hadoop伪分布式集群的运行，需要配置密钥对实现免密登录。

• 创建公私钥对

$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/wux_labs/.ssh/id_rsa): 
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in /home/wux_labs/.ssh/id_rsa
Your public key has been saved in /home/wux_labs/.ssh/id_rsa.pub
The key fingerprint is:
SHA256:rTJMxXd8BoyqSpLN0zS15j+rRKBWiZB9jOcmmWz4TFs wux_labs@wux-labs-vm
The key's randomart image is:
+---[RSA 3072]----+
|  .o o     o.    |
|  ..o.+o. ....   |
|   o.*+.oo. o o  |
|  . BoEo+o . o   |
|   OoB.=S .      |
|  o.Ooo...       |
|   o o+ o.       |
|    .  +  o      |
|        ...o     |
+----[SHA256]-----+

• 复制公钥

cp ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys

解压安装包

将安装包解压到目标路径。

mkdir -p apps
tar -xzf hadoop-3.3.4.tar.gz -C apps

bin目录下存放的是Hadoop相关的常用命令，比如操作HDFS的hdfs命令，以及hadoop、yarn等命令。

etc目录下存放的是Hadoop的配置文件，对HDFS、MapReduce、YARN以及集群节点列表的配置都在这个里面。

sbin目录下存放的是管理集群相关的命令，比如启动集群、启动HDFS、启动YARN、停止集群等的命令。

share目录下存放了一些Hadoop的相关资源，比如文档以及各个模块的Jar包。

配置环境变量

配置环境变量，主要配置HADOOP_HOME和PATH。

vi ~/.bashrc

export HADOOP_HOME=/home/wux_labs/apps/hadoop-3.3.4
export PATH=$HADOOP_HOME/bin:$HADOOP_HOME/sbin:$PATH

让环境变量生效：

source ~/.bashrc

配置文件

除了配置环境变量，伪分布式模式还需要对Hadoop的配置文件进行配置。

• hadoop-env.sh配置

$ vi $HADOOP_HOME/etc/hadoop/hadoop-env.sh

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
export HADOOP_HOME=/home/wux_labs/apps/hadoop-3.3.4
export HADOOP_CONF_DIR=/home/wux_labs/apps/hadoop-3.3.4/etc/hadoop

• core-site.xml配置

$ vi $HADOOP_HOME/etc/hadoop/core-site.xml

<configuration>
    <property>
      <name>fs.defaultFS</name>
      <value>hdfs://wux-labs-vm:8020</value>
    </property>
    <property>
      <name>hadoop.tmp.dir</name>
      <value>/home/wux_labs/data/hadoop/temp</value>
    </property>
    <property>
      <name>hadoop.proxyuser.hadoop.hosts</name>
      <value>*</value>
    </property>
    <property>
      <name>hadoop.proxyuser.hadoop.groups</name>
      <value>*</value>
    </property>
</configuration>

• hdfs-site.xml配置

$ vi $HADOOP_HOME/etc/hadoop/hdfs-site.xml

<configuration>
    <property>
        <name>dfs.replication</name>
        <value>1</value>
    </property>
    <property>
      <name>dfs.namenode.name.dir</name>
      <value>/home/wux_labs/data/hadoop/hdfs/name</value>
    </property>
    <property>
      <name>dfs.datanode.data.dir</name>
      <value>/home/wux_labs/data/hadoop/hdfs/data</value>
    </property>
</configuration>

• mapred-site.xml配置

$ vi $HADOOP_HOME/etc/hadoop/mapred-site.xml

<configuration>
    <property>
        <name>mapreduce.framework.name</name>
        <value>yarn</value>
    </property>
    <property>
        <name>mapreduce.application.classpath</name>
        <value>$HADOOP_HOME/share/hadoop/mapreduce/*:$HADOOP_HOME/share/hadoop/mapreduce/lib/*</value>
    </property>
</configuration>

• yarn-site.xml配置

$ vi $HADOOP_HOME/etc/hadoop/yarn-site.xml

<configuration>
    <property>
      <name>yarn.nodemanager.aux-services</name>
      <value>mapreduce_shuffle</value>
    </property>
      <property>
        <name>yarn.resourcemanager.hostname</name>
        <value>wux-labs-vm</value>
    </property>
</configuration>

格式化NameNode

在启动集群前，需要对NameNode进行格式化，命令如下：

hdfs namenode -format

启动集群

执行以下命令启动集群。

start-all.sh

验证Hadoop

访问HDFS

上传一个文件到HDFS。

hdfs dfs -put .bashrc /

打开HDFS Web UI查看相关信息，默认端口9870。

访问YARN

打开YARN Web UI查看相关信息，默认端口8088。

相关命令

HDFS相关的命令

操作HDFS使用的命令是hdfs，命令格式为：

Usage: hdfs [OPTIONS] SUBCOMMAND [SUBCOMMAND OPTIONS]

支持的Client命令主要有：

    Client Commands:

classpath            prints the class path needed to get the hadoop jar and the required libraries
dfs                  run a filesystem command on the file system
envvars              display computed Hadoop environment variables
fetchdt              fetch a delegation token from the NameNode
getconf              get config values from configuration
groups               get the groups which users belong to
lsSnapshottableDir   list all snapshottable dirs owned by the current user
snapshotDiff         diff two snapshots of a directory or diff the current directory contents with a snapshot
version              print the version

YARN相关的命令

操作HDFS使用的命令是yarn，命令格式为：

Usage: yarn [OPTIONS] SUBCOMMAND [SUBCOMMAND OPTIONS]
 or    yarn [OPTIONS] CLASSNAME [CLASSNAME OPTIONS]
  where CLASSNAME is a user-provided Java class

支持的Client命令主要有：

    Client Commands:

applicationattempt   prints applicationattempt(s) report
app|application      prints application(s) report/kill application/manage long running application
classpath            prints the class path needed to get the hadoop jar and the required libraries
cluster              prints cluster information
container            prints container(s) report
envvars              display computed Hadoop environment variables
fs2cs                converts Fair Scheduler configuration to Capacity Scheduler (EXPERIMENTAL)
jar <jar>            run a jar file
logs                 dump container logs
nodeattributes       node attributes cli client
queue                prints queue information
schedulerconf        Updates scheduler configuration
timelinereader       run the timeline reader server
top                  view cluster information
version              print the version

yarn jar 可以执行一个jar文件。

• 验证案例1，统计含有“dfs”的字符串

创建一个input目录。

hdfs dfs -mkdir /input

将Hadoop的配置文件复制到input目录下。

hdfs dfs -put apps/hadoop-3.3.4/etc/hadoop/*.xml /input/

以下命令用于执行一个Hadoop自带的样例程序，统计input目录中含有dfs的字符串，结果输出到output目录。

yarn jar $HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar grep /input /output 'dfs[a-z.]+'

在YARN上可以看到提交的Job。

执行结果为：

$ hdfs dfs -cat /output/*
1       dfsadmin
1       dfs.replication
1       dfs.namenode.name.dir
1       dfs.datanode.data.dir

• 验证案例2，计算圆周率

同样执行Hadoop自带的案例，计算圆周率。

yarn jar $HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar pi 10 10

执行结果为：

$ yarn jar $HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-examples-3.3.4.jar pi 10 10
Number of Maps  = 10
Samples per Map = 10
Wrote input for Map #0
Wrote input for Map #1
Wrote input for Map #2
Wrote input for Map #3
Wrote input for Map #4
Wrote input for Map #5
Wrote input for Map #6
Wrote input for Map #7
Wrote input for Map #8
Wrote input for Map #9
Starting Job
... ...
Job Finished in 43.768 seconds
Estimated value of Pi is 3.20000000000000000000

在YARN上可以看到提交的Job。