02 . Tomcat多实例并用Nginx反代

Tomcat虚拟主机

​ 一个应用程序在某一个端口启动运行产生了一系列的进程就是一个实例，让tomcat启动两个不同的相互独立的进程，产生两个不同的套接字，分别运行在不同的端口，让不同的端口响应不同的请求，就是多实例.

作用

# 1.多个实例运行相同的应用，实现负载均衡，支持高并发处理，解决session问题.
# 2.多个实例运行不同的应用(类似虚拟主机)

多实例Example

配置三个Tomcat实例，分别运行/webapps/ROOT下的同一网站，达到负载均衡的作用

实例目录	工作端口	实例端口
tomcat_instance1: /usr/local/tomcat/instance1/{conf,logs,temp,work}	8081	8091
tomcat_instance2: /usr/local/tomcat/instance1/{conf,logs,temp,work}	8082	8092
tomcat_instance3: /usr/local/tomcat/instance1/{conf,logs,temp,work}	8083	8093

先部署一个单节点Tomcat

1.安装JDK环境

# CentOS7安装Java，有tar包和rpm包两种
        1>. rpm -ivh jdk-8u121-linux-x64.rpm
        2>. tar xvf jdk-8u151-linux-x64.tar.gz -C /usr/local/
cd /usr/local/
mv jdk1.8.0_151/ jdk
tail -2 /etc/profile
JAVA_HOME=/usr/local/jdk
export PATH=$PATH:$JAVA_HOME/bin
source /etc/profile

2.安装Tomcat

wget http://mirrors.tuna.tsinghua.edu.cn/apache/tomcat/tomcat-8/v8.5.47/bin/apache-tomcat-8.5.47.tar.gz
tar xvf apache-tomcat-8.5.47.tar.gz -C /usr/local/
ln -s /usr/local/apache-tomcat-8.5.47/ /usr/local/tomcat
tail -1 /etc/profile
export CATALINA_HOME=/usr/local/tomcat
source /etc/profile
env |grep -i home
CATALINA_HOME=/usr/local/tomcat
HOME=/root
# 查看熵池的大小：
cat /proc/sys/kernel/random/entropy_avail 180
增加熵池大小，解决Tomcat在CentOS 7巨慢的问题
# 安装rng服务,增大熵池
yum -y install rng-tools
systemctl start rngd && systemctl enable rngd
# 启动服务访问Tomcat页面快一百倍..

3.启动Tomcat

/usr/local/tomcat/bin/catalina.sh start
# ss -antp |grep java
# LISTEN     0      100          *:8009                     *:*                   users:(("java",pid=857,fd=58))
# LISTEN     0      100          *:8080                     *:*                   users:(("java",pid=857,fd=53))
# LISTEN     0      1      127.0.0.1:8005                     *:*                   users:(("java",pid=857,fd=73))
/usr/local/tomcat/bin/shutdown.sh

配置多实例目录

mkdir /webapps/ROOT -p
echo "welcome to tomcat mulit instance" > /webapps/ROOT/index.jsp
echo "hello everyone" > /webapps/ROOT/a.jsp
mkdir -p /usr/local/tomcat/instance{1,2,3}/{conf,logs,temp,work}

配置实例server.xml

\cp /usr/local/tomcat/conf/* /usr/local/tomcat/instance1/conf/
\cp /usr/local/tomcat/conf/* /usr/local/tomcat/instance2/conf/
\cp /usr/local/tomcat/conf/* /usr/local/tomcat/instance3/conf/
# Context配置
# Context作用
# 路径映射
# 应用独立配置，例如单独配置应用日志，单独配置应用访问控制
vim /usr/local/tomcat/instance1/conf/server.xml
<Server port="8091" shutdown="SHUTDOWN">       # 管理实例端口
<Connector port="8081" protocol="HTTP/1.1"     # 提供web服务端口
connectionTimeout="20000"
redirectPort="8443" />
<Host name="localhost" appBase="/webapps"
# 如果两个实例对应两个不同的页面，那么直接修改appBase后端的路径就可以了
unpackWARs="true" autoDeploy="true">
vim /usr/local/tomcat/instance2/conf/server.xml
<Server port="8092" shutdown="SHUTDOWN">
<Connector port="8082" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
<Host name="localhost" appBase="/webapps"
unpackWARs="true" autoDeploy="true">
vim /usr/local/tomcat/instance3/conf/server.xml
<Server port="8093" shutdown="SHUTDOWN">
<Connector port="8083" protocol="HTTP/1.1"
connectionTimeout="20000"
redirectPort="8443" />
<Host name="localhost" appBase="/webapps"
unpackWARs="true" autoDeploy="true">

创建一个脚本方便启动

chmod +x /usr/local/tomcat/instance1/ins1.sh
#每个tomcat下的instance都要创建一个ins1.sh，并且修改里面的instance
#!/bin/bash
#instace1 script
export JAVA_OPTS='-Xms64m -Xmx128m'
#tomcat实例启动时最小分配的内存为64M，最大为128M
export CATALINA_HOME=/usr/local/tomcat
#tomcat的安装目录
export CATALINA_BASE=/usr/local/tomcat/instance1
#实例1的目录
case $1 in
start)
  $CATALINA_HOME/bin/startup.sh
  ;;
stop)
  $CATALINA_HOME/bin/shutdown.sh
  ;;
restart)
  $CATALINA_HOME/bin/shutdown.sh
  sleep 3
  $CATALINA_HOME/bin/startup.sh
  ;;
esac
chmod +x /usr/local/tomcat/instance1/ins1.sh
cp instance1/ins1.sh instance2/
cp instance1/ins1.sh instance3/
vim instance3/ins1.sh
vim instance2/ins1.sh        # 修改tomcat安装目录instanace分别对应什么目录即可
/usr/local/tomcat/instance1/ins1.sh start
/usr/local/tomcat/instance2/ins1.sh start
/usr/local/tomcat/instance3/ins1.sh start
elinks --dump 39.108.140.0:8081
#   welcome to tomcat mulit instance
elinks --dump 39.108.140.0:8082
#   welcome to tomcat mulit instance
elinks --dump 39.108.140.0:8083
#   welcome to tomcat mulit instance

Nginx+Tomcat负载均衡

用户在访问时，需要手动输入端口号，所以需要一个代理服务器，使用nginx做代理，用户访问nginx,然后由nginx访问后端的tomcat。代理方案有两种.

客户端所有请求全部代理到后端Tomcat服务器

修改配置文件，重启服务

# 为了测试看效果使用不同的页面
mkdir /webapp{1..3}
mkdir /webapps1/ROOT
mkdir /webapps2/ROOT
mkdir /webapps3/ROOT
echo webapp1 > /webapps1/ROOT/index.jsp
echo webapp2 > /webapps2/ROOT/index.jsp
echo webapp3 > /webapps3/ROOT/index.jsp
vim /usr/local/tomcat/instance1/conf/server.xml # 分别修改三个配置文件的appBase
vim /usr/local/tomcat/instance2/conf/server.xml
vim /usr/local/tomcat/instance3/conf/server.xml
# 除了修改配置文件appBase，为保证后端Tomcat服务器的日志可以记录客户端真实IP
vim /usr/local/tomcat/instance1/conf/server.xml
prefix="localhost_access_log" suffix=".txt"
               pattern="**%{x-real-ip}i** %l %u %t "%r" %s %b" />
/usr/local/tomcat/instance3/ins1.sh start
/usr/local/tomcat/instance2/ins1.sh start
/usr/local/tomcat/instance1/ins1.sh start

配置Nginx

vim /etc/nginx/nginx.conf
http {
upstream tomcatsrv {
    server 39.108.140.0:8081 weight=1 max_fails=2 fail_timeout=2;
    server 39.108.140.0:8082 weight=1 max_fails=2 fail_timeout=2;
    server 39.108.140.0:8083 weight=1 max_fails=2 fail_timeout=2;
}
vim /etc/nginx/conf.d/default.conf
server {
    listen       80;
    server_name localhost;
    location / {
        proxy_pass http://tomcatsrv;
        proxy_set_header x-real-ip $remote_addr;
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }
nginx -s reload
elinks --dump 39.108.140.0
   webapp1
elinks --dump 39.108.140.0
   webapp2
elinks --dump 39.108.140.0
   webapp3
# 我们去看下tomcat日志是否记录了真实日志
tail -2 /usr/local/tomcat/instance1/logs/localhost_access_log.2019-11-05.txt
39.108.140.0 - - [05/Nov/2019:12:28:17 +0800] "GET / HTTP/1.0" 200 8
47.92.24.137 - - [05/Nov/2019:12:35:13 +0800] "GET / HTTP/1.0" 200 8

客户端访问静态页面由Nginx解析，客户端如访问jsp页面访问请求代理到后端Tomcat服务器

只需要准备一台能解析静态页面的nginx,或者httpd,修改下配置文件即可

vim /etc/nginx/nginx.conf
http {
upstream nginxsrv {
    server 49.233.69.195:80 weight=1 max_fails=2 fail_timeout=2;
    }
upstream tomcatsrv {
    server 39.108.140.0:8081 weight=1 max_fails=2 fail_timeout=2;
    server 39.108.140.0:8082 weight=1 max_fails=2 fail_timeout=2;
    server 39.108.140.0:8083 weight=1 max_fails=2 fail_timeout=2;
    }
vim /etc/nginx/conf.d/default.conf
    location ~* \.html$ {
        root /usr/share/nginx/html;
        index index.html index.htm;
         proxy_pass http://nginxsrv;
         proxy_set_header x-real-ip $remote_addr;
    }
    location ~* \.jsp$ {
        proxy_pass http://tomcatsrv;
        proxy_set_header x-real-ip $remote_addr;
    }
nginx -s reload
elinks --dump 39.108.140.0/index.html
   welcome to nginx
elinks --dump 39.108.140.0/index.jsp
   webapp1
elinks --dump 39.108.140.0/index.jsp
   webapp2

如果tomcat上面搭建的是一个实际的网站，点击登录去登录，却发现登录不成功，可能是session会话不一致的问题

session(会话) 暂时没有使用共享方式，目前采用的会话保持，软件方面可以通过会话同步到数据库是实现session会话共享。

或者前方代理比如Nginx使用ip_hash之类的算法，一个用户固定访问后端的一个web服务器

即将同一个client的访问始终调度到同一后端实例.