How to use Keepalived+Nginx+Tomcat to implement high-availability web cluster

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：

<div id="asf-box">
 <h1 id="pagecontext-servletcontext-serverinfo-request-getheader-x-nginx">${pagecontext.servletcontext.serverinfo}(192.168.224.103)<%=request.getheader("x-nginx")%></h1>
</div>

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：

<div id="asf-box">
 <h1 id="pagecontext-servletcontext-serverinfo-request-getheader-x-nginx">${pagecontext.servletcontext.serverinfo}(192.168.224.104)<%=request.getheader("x-nginx")%></h1>
</div>

2.启动tomcat服务，查看tomcat服务ip信息，此时nginx未启动，因此request-header没有nginx信息。

3.配置nginx代理信息

1.配置master节点[192.168.43.101]代理信息

upstream tomcat {
 server 192.168.43.103:8080 weight=1;
 server 192.168.43.104:8080 weight=1;
}
server{
 location / {
  proxy_pass http://tomcat;
 proxy_set_header x-nginx "nginx-1";
 }
 #......其他省略
}

2.配置backup节点[192.168.43.102]代理信息

upstream tomcat {
 server 192.168.43.103:8080 weight=1;
 server 192.168.43.104:8080 weight=1;
}
server{
 location / {
  proxy_pass http://tomcat;
 proxy_set_header x-nginx "nginx-2";
 }
 #......其他省略
}

3.启动master 节点nginx服务

[root@localhost init.d]# service nginx start
starting nginx (via systemctl):       [ 确定 ]

此时访问 192.168.43.101 可以看到103和104节点tcomat交替显示，说明nginx服务已经将请求负载到了2台tomcat上。

4.同理配置backup[192.168.43.102] nginx信息，启动nginx后，访问192.168.43.102后可以看到backup节点已起到负载的效果。

4.配置keepalived 脚本信息

1. 在master节点和slave节点 /etc/keepalived目录下添加check_nginx.sh 文件，用于检测nginx的存货状况，添加keepalived.conf文件

check_nginx.sh文件信息如下：

#!/bin/bash
#时间变量，用于记录日志
d=`date --date today +%y%m%d_%h:%m:%s`
#计算nginx进程数量
n=`ps -c nginx --no-heading|wc -l`
#如果进程为0，则启动nginx，并且再次检测nginx进程数量，
#如果还为0，说明nginx无法启动，此时需要关闭keepalived
if [ $n -eq "0" ]; then
  /etc/rc.d/init.d/nginx start
  n2=`ps -c nginx --no-heading|wc -l`
  if [ $n2 -eq "0" ]; then
    echo "$d nginx down,keepalived will stop" >> /var/log/check_ng.log
    systemctl stop keepalived
  fi
fi

添加完成后，为check_nginx.sh 文件授权，便于脚本获得执行权限。

[root@localhost keepalived]# chmod -r 777 /etc/keepalived/check_nginx.sh

2.在master 节点 /etc/keepalived目录下，添加keepalived.conf 文件，具体信息如下：

vrrp_script chk_nginx { 
 script "/etc/keepalived/check_nginx.sh" //检测nginx进程的脚本 
 interval 2 
 weight -20 
} 

global_defs { 
 notification_email { 
  //可以添加邮件提醒 
 } 
} 
vrrp_instance vi_1 { 
 state master     #标示状态为master 备份机为backup
 interface ens33    #设置实例绑定的网卡(ip addr查看，需要根据个人网卡绑定)
 virtual_router_id 51   #同一实例下virtual_router_id必须相同 
 mcast_src_ip 192.168.43.101 
 priority 250     #master权重要高于backup 比如backup为240 
 advert_int 1     #master与backup负载均衡器之间同步检查的时间间隔，单位是秒
 nopreempt      #非抢占模式
 authentication {    #设置认证
  auth_type pass   #主从服务器验证方式
  auth_pass 123456 
 } 
 track_script { 
  check_nginx 
 } 
 virtual_ipaddress {   #设置vip
  192.168.43.150   #可以多个虚拟ip，换行即可
 } 
}

3.在backup节点 etc/keepalived目录下添加 keepalived.conf 配置文件

信息如下：

vrrp_script chk_nginx { 
 script "/etc/keepalived/check_nginx.sh" //检测nginx进程的脚本 
 interval 2 
 weight -20 
} 

global_defs { 
 notification_email { 
  //可以添加邮件提醒 
 } 
} 
vrrp_instance vi_1 { 
 state backup     #标示状态为master 备份机为backup
 interface ens33    #设置实例绑定的网卡(ip addr查看)
 virtual_router_id 51   #同一实例下virtual_router_id必须相同 
 mcast_src_ip 192.168.43.102 
 priority 240     #master权重要高于backup 比如backup为240 
 advert_int 1     #master与backup负载均衡器之间同步检查的时间间隔，单位是秒
 nopreempt      #非抢占模式
 authentication {    #设置认证
  auth_type pass   #主从服务器验证方式
  auth_pass 123456 
 } 
 track_script { 
  check_nginx 
 } 
 virtual_ipaddress {   #设置vip
  192.168.43.150   #可以多个虚拟ip，换行即可
 } 
}

tips: 关于配置信息的几点说明

• state - 主服务器需配成master，从服务器需配成backup

• interface - 这个是网卡名，我使用的是vm12.0的版本，所以这里网卡名为ens33

• mcast_src_ip - 配置各自的实际ip地址

• priority - 主服务器的优先级必须比从服务器的高，这里主服务器配置成250，从服务器配置成240

• virtual_ipaddress - 配置虚拟ip（192.168.43.150）

• authentication - auth_pass主从服务器必须一致，keepalived靠这个来通信

• virtual_router_id - 主从服务器必须保持一致

5.集群高可用(ha)验证

step1 启动master机器的keepalived和 nginx服务

[root@localhost keepalived]# keepalived -d -f /etc/keepalived/keepalived.conf
[root@localhost keepalived]# service nginx start

查看服务启动进程

[root@localhost keepalived]# ps -aux|grep nginx
root  6390 0.0 0.0 20484 612 ?  ss 19:13 0:00 nginx: master process /usr/local/nginx/sbin/nginx -c /usr/local/nginx/conf/nginx.conf
nobody  6392 0.0 0.0 23008 1628 ?  s 19:13 0:00 nginx: worker process
root  6978 0.0 0.0 112672 968 pts/0 s+ 20:08 0:00 grep --color=auto nginx

查看keepalived启动进程

[root@localhost keepalived]# ps -aux|grep keepalived
root  6402 0.0 0.0 45920 1016 ?  ss 19:13 0:00 keepalived -d -f /etc/keepalived/keepalived.conf
root  6403 0.0 0.0 48044 1468 ?  s 19:13 0:00 keepalived -d -f /etc/keepalived/keepalived.conf
root  6404 0.0 0.0 50128 1780 ?  s 19:13 0:00 keepalived -d -f /etc/keepalived/keepalived.conf
root  7004 0.0 0.0 112672 976 pts/0 s+ 20:10 0:00 grep --color=auto keepalived

使用 ip add 查看虚拟ip绑定情况，如出现192.168.43.150 节点信息则绑定到master节点

[root@localhost keepalived]# ip add
1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state unknown qlen 1
 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
 inet 127.0.0.1/8 scope host lo
  valid_lft forever preferred_lft forever
 inet6 ::1/128 scope host 
  valid_lft forever preferred_lft forever
2: ens33: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state up qlen 1000
 link/ether 00:0c:29:91:bf:59 brd ff:ff:ff:ff:ff:ff
 inet 192.168.43.101/24 brd 192.168.43.255 scope global ens33
  valid_lft forever preferred_lft forever
 inet 192.168.43.150/32 scope global ens33
  valid_lft forever preferred_lft forever
 inet6 fe80::9abb:4544:f6db:8255/64 scope link 
  valid_lft forever preferred_lft forever
 inet6 fe80::b0b3:d0ca:7382:2779/64 scope link tentative dadfailed 
  valid_lft forever preferred_lft forever
 inet6 fe80::314f:5fe7:4e4b:64ed/64 scope link tentative dadfailed 
  valid_lft forever preferred_lft forever
3: virbr0: <no-carrier,broadcast,multicast,up> mtu 1500 qdisc noqueue state down qlen 1000
 link/ether 52:54:00:2b:74:aa brd ff:ff:ff:ff:ff:ff
 inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
  valid_lft forever preferred_lft forever
4: virbr0-nic: <broadcast,multicast> mtu 1500 qdisc pfifo_fast master virbr0 state down qlen 1000
 link/ether 52:54:00:2b:74:aa brd ff:ff:ff:ff:ff:ff

step 2 启动backup节点nginx服务和keepalived服务，查看服务启动情况，如backup节点出现了虚拟ip，则keepalvied配置文件有问题，此情况称为脑裂。

[root@localhost keepalived]# clear
[root@localhost keepalived]# ip add
1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state unknown qlen 1
 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
 inet 127.0.0.1/8 scope host lo
  valid_lft forever preferred_lft forever
 inet6 ::1/128 scope host 
  valid_lft forever preferred_lft forever
2: ens33: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state up qlen 1000
 link/ether 00:0c:29:14:df:79 brd ff:ff:ff:ff:ff:ff
 inet 192.168.43.102/24 brd 192.168.43.255 scope global ens33
  valid_lft forever preferred_lft forever
 inet6 fe80::314f:5fe7:4e4b:64ed/64 scope link 
  valid_lft forever preferred_lft forever
3: virbr0: <no-carrier,broadcast,multicast,up> mtu 1500 qdisc noqueue state down qlen 1000
 link/ether 52:54:00:2b:74:aa brd ff:ff:ff:ff:ff:ff
 inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
  valid_lft forever preferred_lft forever
4: virbr0-nic: <broadcast,multicast> mtu 1500 qdisc pfifo_fast master virbr0 state down qlen 1000
 link/ether 52:54:00:2b:74:aa brd ff:ff:ff:ff:ff:ff

step 3 验证服务

浏览并多次强制刷新地址： http://192.168.43.150 ,可以看到103和104多次交替显示，并显示nginx-1,则表明 master节点在进行web服务转发。

step 4 关闭master keepalived服务和nginx服务，访问web服务观察服务转移情况

[root@localhost keepalived]# killall keepalived
[root@localhost keepalived]# service nginx stop

此时强制刷新192.168.43.150发现 页面交替显示103和104并显示nginx-2 ，vip已转移到192.168.43.102上，已证明服务自动切换到备份节点上。

step 5 启动master keepalived 服务和nginx服务

此时再次验证发现，vip已被master重新夺回，并页面交替显示 103和104，此时显示nginx-1

四、keepalived抢占模式和非抢占模式

keepalived的ha分为抢占模式和非抢占模式，抢占模式即master从故障中恢复后，会将vip从backup节点中抢占过来。非抢占模式即master恢复后不抢占backup升级为master后的vip。

非抢占模式配置：

1> 在vrrp_instance块下两个节点各增加了nopreempt指令，表示不争抢vip

2> 节点的state都为backup 两个keepalived节点都启动后，默认都是backup状态，双方在发送组播信息后，会根据优先级来选举一个master出来。由于两者都配置了nopreempt，所以master从故障中恢复后，不会抢占vip。这样会避免vip切换可能造成的服务延迟。

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