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Nginx+Keepalived双机热备(主主模式)

[日期:2017-10-28] 来源:Linux社区  作者:legehappy [字体: ]

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。


 
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:
[root@CentOS-4 ~]# 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)
[root@centos-4 ~]# yum -y install gcc pcre-devel zlib-devel openssl-devel
[root@centos-4~]# cd /usr/local/src/
[root@centos-4 src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz
安装nginx
[root@centos-4 src]# tar -zvxfnginx-1.9.7.tar.gz
[root@centos-4 src]# cd nginx-1.9.7
[root@centos-4 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

[root@centos-4 nginx-1.9.7]# make &&make install
[root@centos-1 ~]# yum install -ykeepalived
      (在web1服务器和web2服务器上安装nginx)
[root@centos-2~]# yum -y install gcc pcre-devel zlib-devel openssl-devel
[root@centos-2~]# cd /usr/local/src/
[root@centos-2 src]# wget http://nginx.org/download/nginx-1.9.7.tar.gz
安装nginx
[root@centos-2 src]# tar -zvxfnginx-1.9.7.tar.gz
[root@centos-2 src]# cd nginx-1.9.7
[root@centos-2 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

[root@centos-2 nginx-1.9.7]# make &&make install
三、配置服务:
(所以服务器上配置)
[root@centos-1 ~]# cat/etc/sysconfig/selinux
SELINUX=disabled
[root@centos-1 ~]# getenforce
Disabled
[root@centos-1 ~]# service iptables stop
1、配置keepalived:
(KA1上操作)

[root@centos-1 ~]#cat /etc/keepalived/keepalived.conf
! Configuration Filefor keepalived 
   
global_defs { 
  notification_email { 
    acassen@firewall.loc 
    #failover@firewall.loc 
    #sysadmin@firewall.loc 
  } 
  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)

[root@centos-2 ~]#cat /etc/keepalived/keepalived.conf
! Configuration Filefor keepalived 
   
global_defs { 
  notification_email { 
    acassen@firewall.loc 
    #failover@firewall.loc 
    #sysadmin@firewall.loc 
  } 
  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;
[root@centos-4~]# 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。
[root@centos-1 ~]#service keepalived start
[root@centos-4 ~]# service keepalived start
查看日志文件:
[root@centos-1 ~]# 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。)
[root@centos-4 ~]# 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:
[root@centos-1 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
 
 [root@centos-4 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。)
[root@centos-2 ~]# curl localhost
2

[root@centos-3 ~]# curl localhost
3

(在两台前端服务器上配置)
[root@centos-1 ~]# 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;
        }

 

[root@centos-2 ~]# 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)
[root@centos-1~]# /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。
[root@centos-1~]# /usr/local/nginx/sbin/nginx -s reload
 
[root@centos-4~]# /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
[root@centos-4~]# /usr/local/nginx/sbin/nginx -s reload
[root@centos-1~]# service keepalived restart
停止keepalived:                                          [确定]
正在启动keepalived:                                      [确定]
[root@centos-4~]# 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
[root@centos-1 ~]# curl 192.168.5.200
10.2
[root@centos-1 ~]# 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)
[root@centos-1 ~]# service keepalived stop
停止 keepalived:
[root@centos-1 ~]# 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:
[root@centos-4 ~]# 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
[root@centos-4 ~]# 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
[root@centos-1 ~]# curl 192.168.5.210
10.3
[root@centos-1 ~]# 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)

一些关于Keepalived相关教程集合

CentOS 7下Keepalived + HAProxy 搭建配置详解  http://www.linuxidc.com/Linux/2017-03/141593.htm

Keepalived高可用集群应用场景与配置 http://www.linuxidc.com/Linux/2017-03/141866.htm

Nginx+Keepalived实现站点高可用  http://www.linuxidc.com/Linux/2016-12/137883.htm

Nginx+Keepalived实现站点高可用(负载均衡)  http://www.linuxidc.com/Linux/2016-12/138221.htm

构建高可用集群Keepalived+Haproxy负载均衡 http://www.linuxidc.com/Linux/2016-12/138917.htm

CentOS6.5下 Keepalived高可用服务单实例配置 http://www.linuxidc.com/Linux/2016-12/138110.htm

Keepalived安装与配置 http://www.linuxidc.com/Linux/2017-02/140421.htm

Nginx之Keepalived高可用  http://www.linuxidc.com/Linux/2017-05/143708.htm

Linux下Keepalived服务安装文档  http://www.linuxidc.com/Linux/2017-03/141441.htm

本文永久更新链接地址http://www.linuxidc.com/Linux/2017-10/148061.htm

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