系统综合实践4

(1）使用Docker-compose实现Tomcat+Nginx负载均衡

理解nginx反向代理原理

反向代理（Reverse Proxy）方式是指以代理服务器来接受Internet上的连接请求，然后将请求转发给内部网络上的服务器；并将从服务器上得到的结果返回给Internet上请求连接的客户端，此时代理服务器对外就表现为一个服务器。

nginx代理tomcat集群，代理2个以上tomcat

• 在目录下创建如下文件

docker-compose.yml

version: "3"
services:
    nginx:
        image: nginx
        container_name: jasonginx
        ports:
            - "80:80"
        volumes:
            - ./nginx/default.conf:/etc/nginx/conf.d/default.conf # 挂载配置文件
        depends_on:
            - tomcat01
            - tomcat02
            - tomcat03

    tomcat01:
        image: tomcat
        container_name: jasotomcat1
        volumes:
            - ./tomcat1:/usr/local/tomcat/webapps/ROOT # 挂载web目录

    tomcat02:
        image: tomcat
        container_name: jasotomcat2
        volumes:
            - ./tomcat2:/usr/local/tomcat/webapps/ROOT

    tomcat03:
        image: tomcat
        container_name: jasotomcat3
        volumes:
            - ./tomcat3:/usr/local/tomcat/webapps/ROOT

default.conf

upstream tomcats {
    server jasotomcat1:8080; # 主机名:端口号
    server jasotomcat2:8080; # tomcat默认端口号8080
    server jasotomcat3:8080; # 默认使用轮询策略
}

server {
    listen 80;
    server_name localhost;

    location / {
        proxy_pass http://tomcats; # 请求转向tomcats
    }
}

• 运行docker-compose

docker-compose up -d

• 查看容器

• 查看web端

了解nginx的负载均衡策略，并至少实现nginx的2种负载均衡策略

• 负载均衡策略1：轮询策略

import requests

url="http://127.0.0.1"

for i in range(0,10):
	reponse=requests.get(url)
	print(reponse.text)

• 负载均衡策略2：权重策略
  default.conf

upstream tomcats {
    server lyhtomcat1:8080 weight=1; # 主机名:端口号
    server lyhtomcat2:8080 weight=2; # tomcat默认端口号8080
    server lyhtomcat3:8080 weight=3; # 使用权重策略
}

server {
    listen 80;
    server_name localhost;

    location / {
        proxy_pass http://tomcats; # 请求转向tomcats
    }
}

• 重编一个爬虫查看

import requests

url="http://127.0.0.1"
count={}
for i in range(0,2000):
    response=requests.get(url)
    if response.text in count:
        count[response.text]+=1;
    else:
        count[response.text]=1
for a in count:
    print(a, count[a])

由于tomcat3权重大所以出现频率较高

(2) 使用Docker-compose部署javaweb运行环境

参考项目

• 文件结构

default.conf

upstream tomcats {
    server tomcat4:8080 weight=1; 
    server tomcat5:8080 weight=2; 
    
}

server {
    listen 8080;
    server_name localhost;

    location / {
        proxy_pass http://tomcats; # 请求转向tomcats
        
    }
}

docker-compose.yml

version: '2'
services:
  tomcat01:
    image: tomcat
    hostname: lyhjavaweb
    container_name: tomcat4
    ports:
     - "5050:8080"
    volumes:
     - "$PWD/webapps:/usr/local/tomcat/webapps"
    networks:
      webnet:
        ipv4_address: 15.22.0.15
  tomcat02:
    image: tomcat
    container_name: tomcat5
    ports:
     - "5051:8080"
    volumes:
     - "$PWD/webapps:/usr/local/tomcat/webapps"
    networks:
      webnet:
        ipv4_address: 15.22.0.16
  mymysql:
    build: .
    image: mymysql:test
    container_name: mymysql
    ports:
      - "3306:3306"
    command: [
            '--character-set-server=utf8mb4',
            '--collation-server=utf8mb4_unicode_ci'
    ]
    environment:
      MYSQL_ROOT_PASSWORD: "123456"
    networks:
      webnet:
        ipv4_address: 15.22.0.6
  nginx:
     image: nginx
     ports:
         - "8080:8080"
     volumes:
         - ./default.conf:/etc/nginx/conf.d/default.conf # 挂载配置文件
networks:
 webnet:
   driver: bridge
   ipam:
     config:
       - subnet: 15.22.0.0/24
         gateway: 15.22.0.2

• 修改IP

• 打开终端运行

docker-compose up -d 

• 在web上查看

http://127.0.0.1:5050/ssmgrogshop_war
账号：sa        密码：123

（3）使用Docker搭建大数据集群环境

• pull Ubuntu镜像

docker pull ubuntu

• 创建build文件 运行容器

sudo docker run -it -v /home/ubuntu/build:/root/build --name ubuntu ubuntu

• 进入容器换源

cat<<EOF>/etc/apt/sources.list
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
EOF

• 更新源和安装必要软件

apt-get update
apt-get install vim       
apt-get install ssh  

vim ~/.bashrc #在该文件中最后一行添加如下内容，实现进入Ubuntu系统时，都能自动启动sshd服务    
/etc/init.d/ssh start  

• 配置ssh

cd ~/.ssh  
ssh-keygen -t rsa # 一直按回车即可
cat id_rsa.pub >> authorized_keys 

• 安装JDK

apt install openjdk-8-jdk
vim ~/.bashrc       # 在文件末尾添加以下两行，配置Java环境变量：
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/
export PATH=$PATH:$JAVA_HOME/bin
source ~/.bashrc 
java -version #查看是否安装成功

• 保存配置好的镜像文件

#打开一个新的终端
sudo su
docker ps
docker commit 容器id ubuntu/jdk 

• 安装Hadoop
• 开启保存的那份镜像ubuntu/jdk

docker run -it -v /home/ubuntu/build:/root/build --name ubuntu-jdk ubuntu/jdk

• 将文件复制入共享文件夹

sudo cp /home/ubuntu/Desktop/hadoop-3.1.3.tar.gz /home/ubuntu/build

#在打开的容器里运行
cd /root/build
tar -zxvf hadoop-3.1.3.tar.gz -C /usr/local 
cd /usr/local/hadoop-3.1.3
./bin/hadoop version # 验证安装

• 配置Hadoop集群

cd /usr/local/hadoop-3.1.3/etc/hadoop #进入配置文件存放目录

hadoop-env.sh

vim hadoop-env.sh
export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64/ # 在任意位置添加

core-site.xml

vim core-site.xml

<configuration>
  <property>
    <name>hadoop.tmp.dir</name>
    <value>file:/usr/local/hadoop-3.1.3/tmp</value>
    <description>Abase for other temporary directories.</description>
  </property>
  <property>
    <name>fs.defaultFS</name>
    <value>hdfs://master:9000</value>
  </property>
</configuration>

hdfs-site.xml

vim hdfs-site.xml
<configuration>
    <property>
        <name>dfs.namenode.name.dir</name>
        <value>file:/usr/local/hadoop-3.1.3/namenode_dir</value>
    </property>
    <property>
        <name>dfs.datanode.data.dir</name>
        <value>file:/usr/local/hadoop-3.1.3/datanode_dir</value>
    </property>
    <property>
        <name>dfs.replication</name>
        <value>3</value>
    </property>
</configuration>

mapred-site.xml

vim mapred-site.xml
<configuration>
	<property>
		<name>mapreduce.framework.name</name>
		<value>yarn</value>
	</property>
	<property>
		<name>mapreduce.jobhistory.address</name>
		<value>master:10020</value>
	</property>
	<property>
		<name>mapreduce.jobhistory.webapp.address</name>
		<value>master:19888</value>
	</property>
	<property>
		<name>mapreduce.application.classpath</name>
		<value>/usr/local/hadoop-3.1.3/share/hadoop/mapreduce/lib/*,/usr/local/hadoop-3.1.3/share/hadoop/mapreduce/*</value>
	</property>
</configuration>

yarn-site.xml

<configuration>
    <property>
        <name>yarn.nodemanager.aux-services</name>
        <value>mapreduce_shuffle</value>
    </property>
    <property>
        <name>yarn.resourcemanager.hostname</name>
        <value>master</value>
    </property>
    <property>
        <name>yarn.nodename.vmem-pmem-ratio</name>
        <value>2.7</value>
    </property>
</configuration>

• 修改脚本
  进入脚本文件存放目录：

cd /usr/local/hadoop-3.1.3/sbin

使用vim修改脚本文件
对于start-dfs.sh和stop-dfs.sh文件，添加下列参数(可以放在function{}之后）：

HDFS_DATANODE_USER=root
HADOOP_SECURE_DN_USER=hdfs
HDFS_NAMENODE_USER=root
HDFS_SECONDARYNAMENODE_USER=root

对于start-yarn.sh和stop-yarn.sh，添加下列参数(可以放在function{}之后）：

YARN_RESOURCEMANAGER_USER=root
HADOOP_SECURE_DN_USER=yarn
YARN_NODEMANAGER_USER=root

• 保存镜像

#打开一个新的终端
docker commit 容器id ubuntu/hadoopinstalled

从三个终端分别开启三个容器运行ubuntu/hadoopinstalled镜像，分别表示Hadoop集群中的master,slave01和slave02；

# 第一个终端
sudo docker run -it -h master --name master ubuntu/hadoopinstalled
# 第二个终端
sudo docker run -it -h slave01 --name slave01 ubuntu/hadoopinstalled
# 第三个终端
sudo docker run -it -h slave02 --name slave02 ubuntu/hadoopinstalled

三个终端分别打开/etc/hosts,根据各自ip修改为如下形式

vim /etc/hosts
172.17.0.4      master
172.17.0.5      slave01
172.17.0.6      slave02

在master结点测试ssh；连接到slave结点

ssh slave01
ssh slave02
exit #退出

修改master上workers文件；修改localhost

vim /usr/local/hadoop-3.1.3/etc/hadoop/workers
slave01
slave02

测试Hadoop集群

#在master上操作
cd /usr/local/hadoop-3.1.3
bin/hdfs namenode -format      #首次启动Hadoop需要格式化
sbin/start-all.sh              #启动所有服务
jps                            #分别查看三个终端

运行Hadoop实例程序

/bin/hdfs dfs -mkdir -p /user/hadoop/input
bin/hdfs dfs -put ./etc/hadoop/*.xml /user/hadoop/input
bin/hdfs dfs -ls /user/hadoop/input

执行实例并查看结果

bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-3.1.3.jar grep /user/hadoop/input output 'dfs[a-z.]+'
/bin/hdfs dfs -cat output/*

（4）踩坑总结

• javaweb项目本想自己肝，无奈太菜选择借鉴项目
• 项目构建完成后登录失败，检查后是default.conf没配，加上后重构解决
• 误关终端T T，导致在hadoop集群开启失败，删除容器后三个终端重开解决

（5）花费时间

学习3h+操作8h+博客1h=12h