利用httpd对Tomcat进行负载均衡配置
实验系统：CentOS 6.6_x86_64
实验前提：提前准备好编译环境，防火墙和selinux都关闭
实验说明：本实验共有2台主机，IP分配如拓扑
实验软件：jdk-8u60-linux-x64 apache-tomcat-8.0.24 tomcat-connectors-1.2.41 httpd-2.2.15 httpd-devel-2.2.15
实验拓扑：
一、两台机器安装JAVA环境
1.安装JAVA：
wget http://download.Oracle.com/otn-pub/java/jdk/8u60-b27/jdk-8u60-linux-x64.tar.gz
tar xf jdk-8u60-linux-x64.tar.gz -C /usr/local/
cd /usr/local/
ln -sv jdk1.8.0_60 jdk
2.配置环境变量：
vim /etc/profile.d/jdk.sh
--------------------------------------------------->
JAVA_HOME=/usr/local/jdk
PATH=$JAVA_HOME/bin:$PATH
export JAVA_HOME PATH
<---------------------------------------------------
. /etc/profile.d/jdk.sh
二、两台机器安装tomcat
1.安装tomcat：
wget http://mirrors.cnnic.cn/apache/tomcat/tomcat-8/v8.0.24/bin/apache-tomcat-8.0.24.tar.gz
tar xf apache-tomcat-8.0.24.tar.gz -C /usr/local/
cd /usr/local/
ln -sv apache-tomcat-8.0.24 tomcat
2.配置环境变量：
vim /etc/profile.d/tomcat.sh
--------------------------------------------------->
CATALINA_BASE=/usr/local/tomcat
PATH=$CATALINA_BASE/bin:$PATH
export PATH CATALINA_BASE
<---------------------------------------------------
. /etc/profile.d/tomcat.sh
3.查看tomcat及JAVA状态：
catalina.sh version
4.提供启动脚本：
vim /etc/init.d/tomcat
-------------------------------------------------------->
#!/bin/sh
# Tomcat init script for Linux.
#
# chkconfig: 2345 96 14
# description: The Apache Tomcat servlet/JSP container.
# JAVA_OPTS='-Xms64m -Xmx128m'
JAVA_HOME=/usr/local/jdk
CATALINA_HOME=/usr/local/tomcat
export JAVA_HOME CATALINA_HOME
case $1 in
start)
exec $CATALINA_HOME/bin/catalina.sh start ;;
stop)
exec $CATALINA_HOME/bin/catalina.sh stop;;
restart)
$CATALINA_HOME/bin/catalina.sh stop
sleep 2
exec $CATALINA_HOME/bin/catalina.sh start ;;
*)
echo "Usage: `basename $0` {start|stop|restart}"
exit 1
;;
esac
<--------------------------------------------------------
chmod +x /etc/init.d/tomcat
chkconfig --add tomcat
5.编辑tomcat配置文件，只添加jvmRoute参数：
在19.66上：
vim /usr/local/tomcat/conf/server.xml
----------------------------------------------->
<Engine name="Catalina" defaultHost="localhost" jvmRoute="TomcatA"> //指明这是TomcatA主机
在19.74上：
vim /usr/local/tomcat/conf/server.xml
----------------------------------------------->
<Engine name="Catalina" defaultHost="localhost" jvmRoute="TomcatB">
6.提供测试页面：
在19.66上：
mkdir -pv /usr/local/tomcat/webapps/test/WEB-INF/{classes,lib}
vim /usr/local/tomcat/webapps/test/index.jsp
------------------------------------------------------------------------>
<%@ page language="java" %>
<%@ page import="java.util.*" %>
<html>
<head>
<title>test</title>
</head>
<body>
<%
out.println("This is TomcatA");
%>
</body>
</html>
------------------------------------------------------------------------>
service tomcat start
在19.74上：
mkdir -pv /usr/local/tomcat/webapps/test/WEB-INF/{classes,lib}
vim /usr/local/tomcat/webapps/test/index.jsp
------------------------------------------------------------------------>
<%@ page language="java" %>
<%@ page import="java.util.*" %>
<html>
<head>
<title>test</title>
</head>
<body>
<%
out.println("This is TomcatB");
%>
</body>
</html>
------------------------------------------------------------------------>
service tomcat start
三、利用mod_jk模块对tomcat进行负载均衡
利用httpd反向代理tomcat时有两种方法，分别要用到mod_proxy和mod_jk这两个模块。mod_jk需要额外编译安装，而mod_proxy需要用到httpd的proxy_module、proxy_balancer_module、proxy_http_module、proxy_ajp_module模块，确保安装时这些模块都被安装了。从httpd2.2开始，这些模块默认就是安装的，所以这里我们直接用yum安装即可。
下面先演示利用mod_jk模块对tomcat进行负载均衡。此模块只需要在一台机器上安装，我们这里在19.66上安装。
1.安装httpd：
yum -y install httpd httpd-devel //安装httpd-devel为了提供apxs
2.安装mod_jk.so模块：
wget http://mirrors.cnnic.cn/apache/tomcat/tomcat-connectors/jk/tomcat-connectors-1.2.41-src.tar.gz
tar xf tomcat-connectors-1.2.41-src.tar.gz
cd tomcat-connectors-1.2.41-src/native/
./configure --with-apxs=/usr/sbin/apxs
make && make install
3.提供额外的httpd模块配置文件：
vim /etc/httpd/conf.d/httpd-jk.conf
------------------------------------------------------>
# Load the mod_jk
LoadModule jk_module modules/mod_jk.so //加载mod_jk.so模块
JkWorkersFile /etc/httpd/conf.d/workers.properties //此模块自己要用到的配置文件
JkLogFile logs/mod_jk.log
JkLogLevel debug
JkMount /* lb1 //访问根下的所有内容都发到集群lb1中来
JkMount /status/ stat1
4.配置mod_jk模块的配置文件workers.properties：
vim /etc/httpd/conf.d/workers.properties
-------------------------------------------------------->
worker.list = lb1,stat1
worker.TomcatA.type = ajp13 //httpd连接tomcat所用的模式
worker.TomcatA.host = 192.168.19.66
worker.TomcatA.port = 8009
worker.TomcatA.lbfactor = 1 //权重
worker.TomcatB.type = ajp13
worker.TomcatB.host = 192.168.19.74
worker.TomcatB.port = 8009
worker.TomcatB.lbfactor = 1
worker.lb1.type = lb //调度方式
worker.lb1.sticky_session = 0 //是否使用session绑定
worker.lb1.balance_workers = TomcatA, TomcatB
worker.stat1.type = status
5.启动测试：
service httpd start
用浏览器打开http://192.168.19.66/test，我们不断刷新，可以看到实验效果。
四、利用mod_proxy模块对tomcat进行负载均衡
1.仍然在19.66上编辑即可，使用http协议：
cd /etc/httpd/conf.d/
mv httpd-jk.conf httpd-jk.conf.bak
vim httpd-proxy.conf
-------------------------------------------------------------->
<Proxy balancer://lb1>
BalancerMember http://192.168.19.66:8080 loadfactor=1 route=TomcatA
BalancerMember http://192.168.19.74:8080 loadfactor=1 route=TomcatB
ProxySet lbmethod=byrequests //基于权重将统计请求个数进行调度
</Proxy>
ProxyPass / balancer://lb1/
ProxyPassReverse / balancer://lb1/
<--------------------------------------------------------------
service httpd restart
2.使用ajp协议：
cd /etc/httpd/conf.d/
mv httpd-jk.conf httpd-jk.conf.bak
vim httpd-proxy.conf
-------------------------------------------------------------->
<Proxy balancer://lb1>
BalancerMember ajp://192.168.19.66:8009 loadfactor=1 route=TomcatA
BalancerMember ajp://192.168.19.74:8009 loadfactor=1 route=TomcatB
ProxySet lbmethod=byrequests
</Proxy>
ProxyPass / balancer://lb1/
ProxyPassReverse / balancer://lb1/
<--------------------------------------------------------------
service httpd restart
以上两种办法都可以实现负载均衡，刷新页面仍然可以看到效果，这里就不在给出图片了。至此，实验全部结束，谢谢！
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