这篇文章主要介绍Keepalived+Nginx+Tomcat如何实现高可用Web集群，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
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Keepalived+Nginx+Tomcat 实现高可用Web集群
一、Nginx的安装过程
1.下载Nginx安装包，安装依赖环境包
(1)安装 C++编译环境
yum -y install gcc #C++
(2)安装pcre
yum -y install pcre-devel
(3)安装zlib
yum -y install zlib-devel
(4)安装Nginx
定位到nginx 解压文件位置，执行编译安装命令
[root@localhost nginx-1.12.2]# pwd
/usr/local/nginx/nginx-1.12.2
[root@localhost nginx-1.12.2]# ./configure && make && make install
(5)启动Nginx
安装完成后先寻找那安装完成的目录位置
[root@localhost nginx-1.12.2]# whereis nginx
nginx: /usr/local/nginx
[root@localhost nginx-1.12.2]#
进入Nginx子目录sbin启动Nginx
[root@localhost sbin]# ls
nginx
[root@localhost sbin]# ./nginx &
[1] 5768
[root@localhost sbin]#
查看Nginx是否启动
或通过进程查看Nginx启动情况
[root@localhost sbin]# ps -aux|grep nginx
root 5769 0.0 0.0 20484 608 ? Ss 14:03 0:00 nginx: master process ./nginx
nobody 5770 0.0 0.0 23012 1620 ? S 14:03 0:00 nginx: worker process
root 5796 0.0 0.0 112668 972 pts/0 R+ 14:07 0:00 grep --color=auto nginx
[1]+ 完成 ./nginx
[root@localhost sbin]#
到此Nginx安装完成并启动成功。
(6)Nginx快捷启动和开机启动配置
编辑Nginx快捷启动脚本【 注意Nginx安装路径， 需要根据自己的NGINX路径进行改动】
[root@localhost init.d]# vim /etc/rc.d/init.d/nginx
#!/bin/sh
#
# nginx - this script starts and stops the nginx daemon
#
# chkconfig: - 85 15
# description: Nginx is an HTTP(S) server, HTTP(S) reverse \
# proxy and IMAP/POP3 proxy server
# processname: nginx
# config: /etc/nginx/nginx.conf
# config: /usr/local/nginx/conf/nginx.conf
# pidfile: /usr/local/nginx/logs/nginx.pid
# Source function library.
. /etc/rc.d/init.d/functions
# Source networking configuration.
. /etc/sysconfig/network
# Check that networking is up.
[ "$NETWORKING" = "no" ] && exit 0
nginx="/usr/local/nginx/sbin/nginx"
prog=$(basename $nginx)
NGINX_CONF_FILE="/usr/local/nginx/conf/nginx.conf"
[ -f /etc/sysconfig/nginx ] && . /etc/sysconfig/nginx
lockfile=/var/lock/subsys/nginx
make_dirs() {
# make required directories
user=`$nginx -V 2>&1 | grep "configure arguments:" | sed 's/[^*]*--user=\([^ ]*\).*/\1/g' -`
if [ -z "`grep $user /etc/passwd`" ]; then
useradd -M -s /bin/nologin $user
fi
options=`$nginx -V 2>&1 | grep 'configure arguments:'`
for opt in $options; do
if [ `echo $opt | grep '.*-temp-path'` ]; then
value=`echo $opt | cut -d "=" -f 2`
if [ ! -d "$value" ]; then
# echo "creating" $value
mkdir -p $value && chown -R $user $value
fi
fi
done
}
start() {
[ -x $nginx ] || exit 5
[ -f $NGINX_CONF_FILE ] || exit 6
make_dirs
echo -n $"Starting $prog: "
daemon $nginx -c $NGINX_CONF_FILE
retval=$?
echo
[ $retval -eq 0 ] && touch $lockfile
return $retval
}
stop() {
echo -n $"Stopping $prog: "
killproc $prog -QUIT
retval=$?
echo
[ $retval -eq 0 ] && rm -f $lockfile
return $retval
}
restart() {
#configtest || return $?
stop
sleep 1
start
}
reload() {
#configtest || return $?
echo -n $"Reloading $prog: "
killproc $nginx -HUP
RETVAL=$?
echo
}
force_reload() {
restart
}
configtest() {
$nginx -t -c $NGINX_CONF_FILE
}
rh_status() {
status $prog
}
rh_status_q() {
rh_status >/dev/null 2>&1
}
case "$1" in
start)
rh_status_q && exit 0
$1
;;
stop)
rh_status_q || exit 0
$1
;;
restart|configtest)
$1
;;
reload)
rh_status_q || exit 7
$1
;;
force-reload)
force_reload
;;
status)
rh_status
;;
condrestart|try-restart)
rh_status_q || exit 0
;;
*)
echo $"Usage: $0 {start|stop|status|restart|condrestart|try-restart|reload|force-reload|configtest}"
exit 2
esac为启动脚本授权 并加入开机启动
[root@localhost init.d]# chmod -R 777 /etc/rc.d/init.d/nginx
[root@localhost init.d]# chkconfig nginx
启动Nginx
[root@localhost init.d]# ./nginx start
将Nginx加入系统环境变量
[root@localhost init.d]# echo 'export PATH=$PATH:/usr/local/nginx/sbin'>>/etc/profile && source /etc/profile
Nginx命令 [ service nginx (start|stop|restart) ]
[root@localhost init.d]# service nginx start
Starting nginx (via systemctl): [ 确定 ]
Tips: 快捷命令
service nginx (start|stop|restart)
二、KeepAlived安装和配置
1.安装Keepalived依赖环境
yum install -y popt-devel
yum install -y ipvsadm
yum install -y libnl*
yum install -y libnf*
yum install -y openssl-devel
2.编译Keepalived并安装
[root@localhost keepalived-1.3.9]# ./configure
[root@localhost keepalived-1.3.9]# make && make install
3.将Keepalive 安装成系统服务
[root@localhost etc]# mkdir /etc/keepalived
[root@localhost etc]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
手动复制默认的配置文件到默认路径
[root@localhost etc]# mkdir /etc/keepalived
[root@localhost etc]# cp /usr/local/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
[root@localhost etc]# cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
为keepalived 创建软链接
[root@localhost sysconfig]# ln -s /usr/local/keepalived/sbin/keepalived /usr/sbin/
设置Keepalived开机自启动
[root@localhost sysconfig]# chkconfig keepalived on
注意：正在将请求转发到“systemctl enable keepalived.service”。
Created symlink from /etc/systemd/system/multi-user.target.wants/keepalived.service to /usr/lib/systemd/system/keepalived.service
启动Keepalived服务
[root@localhost keepalived]# keepalived -D -f /etc/keepalived/keepalived.conf
关闭Keepalived服务
[root@localhost keepalived]# killall keepalived
三、集群规划和搭建
环境准备：
CentOS 7.2
Keepalived Version 1.4.0 - December 29, 2017
Nginx Version: nginx/1.12.2
Tomcat Version:8
集群规划清单
| 虚拟机 | IP | 说明 | | Keepalived+Nginx1[Master] | 192.168.43.101 | Nginx Server 01 |
| Keeepalived+Nginx[Backup] | 192.168.43.102 | Nginx Server 02 |
| Tomcat01 | 192.168.43.103 | Tomcat Web Server01 |
| Tomcat02 | 192.168.43.104 | Tomcat Web Server02 |
| VIP | 192.168.43.150 | 虚拟漂移IP |
1.更改Tomcat默认欢迎页面，用于标识切换Web
更改TomcatServer01 节点ROOT/index.jsp 信息，加入TomcatIP地址，并加入Nginx值，即修改节点192.168.43.103信息如下：
${pageContext.servletContext.serverInfo}(192.168.224.103)<%=request.getHeader("X-NGINX")%>
更改TomcatServer02 节点ROOT/index.jsp信息，加入TomcatIP地址，并加入Nginx值，即修改节点192.168.43.104信息如下：
