Nginx+keepalived双机热备(主主模式)

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nginx+keepalived实现高可用负载均衡的主主模式

由于网站的访问需求不断加大,负载越来越高。现需要在web前端放置nginx负载均衡,同时结合keepalived对前端nginx实现HA高可用。
1
、nginx进程基于Master+Slave(worker模式)多进程模型,自身具有非常稳定的子进程管理功能。在Master进程分配模式下,Master进程永远不进行业务处理,只是进行任务分发,从而达到Master进程的存活高可靠性,Slave(worker)进程所有的业务信号都由主进程发出,Slave(worker)进程所有的超时任务都会被Master中止,属于非阻塞式任务模型。
2
、Keepalived是Linux下面实现VRRP备份路由的高可靠性运行件。基于Keepalived设计的服务模式能够真正做到主服务器和备份服务器故障时IP瞬间无缝交接。二者结合,可以构架出比较稳定的软件LB方案。

技术分享

 

双机高可用方法目前分为两种:
1)双机主从模式即前端使用两台服务器,一台主服务器和一台热备服务器,正常情况下,主服务器绑定一个公网虚拟IP,提供负载均衡服务,热备服务器处于空闲状态;当主服务器发生故障时,热备服务器接管主服务器的公网虚拟IP,提供负载均衡服务;但是热备服务器在主机器不出现故障的时候,永远处于浪费状态,对于服务器不多的网站,该方案不经济实惠。
2)双机主主模式这种模式的效果很强大,即前端使用两台负载均衡服务器,互为主备,且都处于活动状态(这样达到不浪费服务器),同时各自绑定一个公网虚拟IP,提供负载均衡服务;当其中一台发生故障时,另一台接管发生故障服务器的公网虚拟IP(这时由非故障机器一台负担所有的请求)。这种方案,经济实惠,非常适合于当前架构环境。

 

一、环境介绍:

操作系统:

[[email protected] ~]# cat /etc/redhat-release

CentOS release 6.9 (Final)

服务器对应关系:

KA1:192.168.5.129 centos-1

KA2:192.168.5.128 centos-4

Vip1:192.168.5.200  129master/128backup

VIP2:192.168.5.210  128master/129backup

Web1:192.168.5.131 centos-2

Web2:192.168.5.132 centos-3

二、环境安装:

安装依赖:

(在KA1和KA2机器上执行以下步骤)
[[email protected]centos-4 ~]# yum -y install gcc pcre-devel zlib-devel openssl-devel

[[email protected]~]# cd /usr/local/src/
[[email protected] src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz

安装nginx
[[email protected] src]# tar -zvxfnginx-1.9.7.tar.gz 
[[email protected] src]# cd nginx-1.9.7

[[email protected] nginx-1.9.7]#./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre


[[email protected] nginx-1.9.7]# make &&make install

[[email protected] ~]# yum install -ykeepalived

       (在web1服务器和web2服务器上安装nginx)

[[email protected]~]# yum -y install gcc pcre-devel zlib-devel openssl-devel

[[email protected]~]# cd /usr/local/src/
[[email protected] src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz

安装nginx
[[email protected] src]# tar -zvxfnginx-1.9.7.tar.gz 
[[email protected] src]# cd nginx-1.9.7

[[email protected] nginx-1.9.7]# ./configure --prefix=/usr/local/nginx --user=nginx --group=nginx--with-http_ssl_module --with-http_flv_module --with-http_stub_status_module--with-http_gzip_static_module --with-pcre


[[email protected] nginx-1.9.7]# make &&make install

三、配置服务:

(所以服务器上配置)

[[email protected] ~]# cat/etc/sysconfig/selinux

SELINUX=disabled

[[email protected] ~]# getenforce

Disabled

[[email protected] ~]# service iptables stop

1、配置keepalived:

(KA1上操作)

[[email protected] ~]#cat /etc/keepalived/keepalived.conf
! Configuration Filefor keepalived  
  
global_defs {  
   notification_email {  
     [email protected]  
     #[email protected]  
     #[email protected]  
   }  
   router_id LVS_DEVEL  
}  
 vrrp_scriptchk_http_port {        
    script "/opt/check_nginx.sh"   
    interval 2                      
    weight -5                       
    fall 2                   
    rise 1                  
}
  
vrrp_instance VI_1{  
    state MASTER
    interface eth0  
    virtual_router_id 51  
    priority 100  
    advert_int 1  
    authentication {  
        auth_type PASS  
        auth_pass 1111  
    }  
    virtual_ipaddress {  
        192.168.5.200  
    }  
} 
 
vrrp_instance VI_2{  
    state BACKUP
    interface eth0
    virtual_router_id 50
    priority 90
    advert_int 1  
    authentication {  
        auth_type PASS
        auth_pass 1111  
    }
    virtual_ipaddress {
        192.168.5.210
}
track_script {                     
   chk_http_port                 
}
 
}


(KA2上操作)

[[email protected] ~]#cat /etc/keepalived/keepalived.conf
! Configuration Filefor keepalived  
  
global_defs {  
   notification_email {  
     [email protected]  
     #[email protected]  
     #[email protected]  
   }  
   router_id LVS_DEVEL  
}  
 vrrp_scriptchk_http_port {        
    script "/opt/check_nginx.sh"   
    interval 2                      
    weight -5                       
    fall 2                   
    rise 1                  
}
  
vrrp_instance VI_1{  
    state BACKUP
    interface eth0  
    virtual_router_id 51  
    priority 90 
    advert_int 1  
    authentication {  
        auth_type PASS  
        auth_pass 1111  
    }  
    virtual_ipaddress {  
        192.168.5.200  
    }  
} 
 
vrrp_instance VI_2{  
    state MASTER
    interface eth0
    virtual_router_id 50
    priority 100
    advert_int 1  
    authentication {  
        auth_type PASS
        auth_pass 1111  
    }
    virtual_ipaddress {
        192.168.5.210
}
track_script {                     
     chk_http_port                 
}
}


编写一个监控nginx的脚本:

需要注意的是,要判断本机nginx是否正常,如果发现nginx不正常,重启之后,等待三秒在校验,任然失败则不尝试,关闭keepalived,发送邮件,其他主机此时接管VIP;

[[email protected]~]# cat /opt/check_nginx.sh
#!/bin/bash
check=$(ps-C nginx --no-heading|wc -l)
IP=`ipadd | grep eth0 | awk  ‘NR==2{print $2}‘| awk -F ‘/‘ ‘{print $1}‘`
if ["${check}" = "0" ]; then
    /usr/local/nginx/sbin/nginx
    sleep 2
    counter=$(ps -C nginx --no-heading|wc -l)
    if [ "${check}" = "0"]; then
        /etc/init.d/keepalived stop
       echo "check $IP nginx is down"| mail -s "check keepalived nginx" *********@qq.com
    fi
fi

(KA1一样的监控脚本)

2、在两台前端服务器上启动keepalived服务,对于192.168.5.200的vip centos-1是master/192.168.5.210的vip centos-1是backup。

[[email protected] ~]#service keepalived start

[[email protected] ~]# service keepalived start

查看日志文件:

[[email protected] ~]# cat /var/log/messages

Oct 19 22:00:22 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

Oct 19 22:00:22 centos-1 Keepalived_healthcheckers[46183]: Netlinkreflector reports IP 192.168.5.210 added

Oct 19 22:00:24 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_1)Sending gratuitous ARPs on eth0 for 192.168.5.200

Oct 19 22:00:27 centos-1 Keepalived_vrrp[46184]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

(因为KA1先启动keepalived服务所以两个vip都会在KA1上,但第二台keepaliver服务起来后vip2就会被KA2抢占回来。)

[[email protected] ~]# cat /var/log/messages

Oct 19 22:01:38 centos-4 Keepalived_healthcheckers[15009]: Netlinkreflector reports IP 192.168.5.210 added

Oct 19 22:01:38 centos-4 avahi-daemon[1513]: Registering new addressrecord for 192.168.5.210 on eth0.IPv4.

Oct 19 22:01:38 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

Oct 19 22:01:43 centos-4 Keepalived_vrrp[15010]: VRRP_Instance(VI_2)Sending gratuitous ARPs on eth0 for 192.168.5.210

查看ip addr:

[[email protected] keepalived]# ip add

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_faststate UP qlen 1000

    link/ether00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff

    inet 192.168.5.129/24 brd192.168.5.255 scope global eth0

    inet 192.168.5.200/32scope global eth0

 

 [[email protected] keepalived]#ip addr

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdiscpfifo_fast state UP qlen 1000

    link/ether00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff

    inet 192.168.5.128/24 brd192.168.5.255 scope global eth0

         inet 192.168.5.210/32 scope global eth0

3、配置nginx的反向代理

(在web1和web2服务器上配置两个web服务(可以http或者nginx)用来测试使用,这里就不一一演示了。)

[[email protected] ~]# curl localhost

  1. 2

[[email protected] ~]# curl localhost

  1. 3

(在两台前端服务器上配置)

[[email protected] ~]# vim/usr/local/nginx/conf/nginx.conf
……
……
……
upstreambackend {
      ip_hash;
      server 192.168.5.131:80 max_fails=2fail_timeout=30s;
      server 192.168.5.132:80 max_fails=2fail_timeout=30s;
#ip_hash: 每个请求按访问ip的hash结果分配,这样每个访客固定访问一个后端服务器,可以解决session的问题。
#max_fails=2 为允许失败的次数,默认值为1
#fail_timeout=30s 当max_fails次失败后,暂停将请求分发到该后端服务器的时间
}
 
   proxy_temp_path   /usr/local/nginx/cache/tmp 1 2;
   proxy_cache_path  /usr/local/nginx/cache  levels=1:2 keys_zone=cache1:100m inactive=1dmax_size=10g;
……
……
……
    server {
        listen       80;
        server_name  localhost;
 
        #charset koi8-r;
 
        #access_log  logs/host.access.log  main;
 
        location / {
          proxy_pass http://backend;
         proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
 
        proxy_cache cache1;
        add_header X-Cache$upstream_cache_status;
        proxy_cache_key $host$uri$is_args$args;
        proxy_cache_valid 200 304 10m;
        expires 30d;
 
#            root   /web;
            index  index.php index.html index.htm;
        }
[[email protected] ~]# vim/usr/local/nginx/conf/nginx.conf
……
……
……
upstreambackend {
      ip_hash;
      server 192.168.5.131:80 max_fails=2fail_timeout=30s;
      server 192.168.5.132:80 max_fails=2fail_timeout=30s;
}
 
   proxy_temp_path   /usr/local/nginx/cache/tmp 1 2;
   proxy_cache_path  /usr/local/nginx/cache  levels=1:2 keys_zone=cache1:100m inactive=1dmax_size=10g;
……
……
……
    server {
        listen       80;
        server_name  localhost;
 
        #charset koi8-r;
 
        #access_log  logs/host.access.log  main;
 
        location / {
          proxy_pass http://backend;
         proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
 
        proxy_cache cache1;
        add_header X-Cache$upstream_cache_status;
        proxy_cache_key $host$uri$is_args$args;
        proxy_cache_valid 200 304 10m;
        expires 30d;
 
#            root   /web;
            index  index.php index.html index.htm;
        }

(两台KA1和KA2服务器重启nginx、keepalived服务)

[[email protected]~]# /usr/local/nginx/sbin/nginx -t

nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok

nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful ###检查配置文件没问题后再执行重启nginx。

[[email protected]~]# /usr/local/nginx/sbin/nginx -s reload

 

[[email protected]~]# /usr/local/nginx/sbin/nginx -t

nginx:the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok

nginx:configuration file /usr/local/nginx/conf/nginx.conf test is successful

[[email protected]~]# /usr/local/nginx/sbin/nginx -s reload

[[email protected]~]# service keepalived restart

停止keepalived:                                          [确定]

正在启动keepalived:                                      [确定]

[[email protected]~]# service keepalived restart

停止keepalived:                                          [确定]

正在启动keepalived:                                      [确定]

 

四、测试:

验证方法(保证从负载均衡器本机到后端真实服务器之间能正常通信)

(1)、先测试完成后的效果访问vip1、vip2

[[email protected] ~]# curl 192.168.5.200

10.2

[[email protected] ~]# curl 192.168.5.210

10.3

(注意在KA1、KA2上做了缓存和ip_hash)

(2)、把KA1keepalived stop掉(模拟KA1主机的keepalived故障)

[[email protected] ~]# service keepalived stop

停止 keepalived:

[[email protected] ~]# ip addr

2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000

   link/ether 00:0c:29:0d:f3:5d brd ff:ff:ff:ff:ff:ff

   inet 192.168.5.129/24 brd 192.168.5.255 scope global eth0

   inet6 fe80::20c:29ff:fe0d:f35d/64 scope link

      valid_lft forever preferred_lft forever

(KA1主机上查看ip addr已经没有vip了。)

在KA2主机上查看日志文件

[[email protected] ~]# cat /var/log/messages

Oct 19 23:20:46 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200

Oct 19 23:20:46 centos-4avahi-daemon[1513]: Registering new address record for 192.168.5.200 oneth0.IPv4.

Oct 19 23:20:46 centos-4 Keepalived_healthcheckers[15411]:Netlink reflector reports IP 192.168.5.200 added

Oct 19 23:20:51 centos-4Keepalived_vrrp[15412]: VRRP_Instance(VI_1) Sending gratuitous ARPs on eth0 for192.168.5.200

(日志文件显示已经把vip:192.168.5.200接管了)

查看KA2主机的ip addr

[[email protected] ~]# ip addr

2: eth0:<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen1000

   link/ether 00:50:56:3a:84:30 brd ff:ff:ff:ff:ff:ff

   inet 192.168.5.128/24 brd 192.168.5.255 scope global eth0

   inet 192.168.5.210/32 scope global eth0

   inet 192.168.5.200/32 scope global eth0

 (可以看到已经有两个vip

检查nginx服务是否被KA2接管且不中断

[[email protected] ~]# curl 192.168.5.210

10.3

[[email protected] ~]# curl 192.168.5.200

10.2

(可以看到服务还是进行的而且缓存还在。ip_hash的作用)


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