Nginx+Keepalived实现Nginx高可用负载均衡

一、说明

    在架构设计中，可以利用NGINX的反向代理和负载均衡实现后端应用的高可用性，同时我们还需要考虑Nginx的单点故障。真正做到架构高可用性。

主要考虑以下几点：

 1、Nginx服务因为意外现象挂掉

 2、服务器宕机导致NGINX不可用

二、环境准备

# 准备四台机器，两台nginx主备，两台web

三、安装配置相关服务

1、安装nginx（192.168.182.128，192.168.182.129）

# 添加Nginx到YUM源

rpm -Uvh http://nginx.org/packages/centos/7/noarch/RPMS/nginx-release-centos-7-0.el7.ngx.noarch.rpm

# 安装Nginx

yum install -y nginx

# 启动服务

systemctl start nginx.service

2、安装web服务,Apache（192.168.182.130，192.168.182.131）

# 关闭防护墙systemctl stop firewalld.servicesystemctl enable firewalld.service# 安装yum -y install httpd
　# 修改默认页（192.168.182.130）　echo ‘192.168.182.130‘> /usr/share/httpd/noindex/index.html
 # 修改默认页（192.168.182.131）　echo ‘192.168.182.131‘> /usr/share/httpd/noindex/index.html 
 # 启动服务 systemctl start httpd.service


3、配置nginx反向代理，实现负载均衡
# 配置文件

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
include /usr/share/nginx/modules/*.conf;
events {
    worker_connections 1024;
}
http {
    log_format  main  ‘$remote_addr - $remote_user [$time_local] "$request" ‘
                      ‘$status $body_bytes_sent "$http_referer" ‘
                      ‘"$http_user_agent" "$http_x_forwarded_for"‘;
    access_log  /var/log/nginx/access.log  main;
    sendfile            on;
    tcp_nopush          on;
    tcp_nodelay         on;
    keepalive_timeout   65;
    types_hash_max_size 2048;
    include             /etc/nginx/mime.types;
    default_type        application/octet-stream;
    #include /etc/nginx/conf.d/*.conf;
    upstream myServer {
       server 192.168.182.130:80 weight=1;
       server 192.168.182.131:80 weight=1;
    }
    server {
        listen       80 default_server;
        listen       [::]:80 default_server;
        server_name  _;
        # root         /usr/share/nginx/html;
        # include /etc/nginx/default.d/*.conf;
        location / {
            proxy_pass   http://myServer;  
            index  index.html index.htm; 
        }
        error_page 404 /404.html;
            location = /40x.html {
        }
        error_page 500 502 503 504 /50x.html;
            location = /50x.html {
        }
    }
}

# 重启nginx服务

systemctl restart nginx.service

# 测试

C:\Users\29209>curl 192.168.182.128
192.168.182.130

C:\Users\29209>curl 192.168.182.128
192.168.182.131

C:\Users\29209>curl 192.168.182.128
192.168.182.130

C:\Users\29209>curl 192.168.182.128
192.168.182.131

3、安装配置keepalived，实现高可用（192.168.182.130，192.168.182.131）

yum install -y  keepalived

#  配置主

! Configuration File for keepalived

global_defs {
   notification_email {
     
     
     
   }
   notification_email_from 
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id nginx01  # router_id  唯一标识符
   vrrp_skip_check_adv_addr
   # vrrp_strict # 如果访问不了VIP，就去掉，这里我注释掉了
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_script check_nginx {  
    script "/etc/keepalived/chknginx.sh"   #nginx服务检查脚本
    interval 1
    weight -2
}

vrrp_instance VI_1 {
    state MASTER
    interface ens33  # 网卡名  
    virtual_router_id 52  # 默认为51  配置完发现主备切换有问题 更改为52 发现好了  原因未知
    priority 150     # 主备的优先级priority，数字越大，优先级越高
    advert_int 1     # 检查时间1秒
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script  {
    check_nginx
    }

    virtual_ipaddress {
        192.168.182.230/24  dev ens33 label ens33:7  #vip地址 
    }
}
}

# 检测脚本文件/etc/keepalived/chknginx.sh

#!/bin/bash
# auto check nginx process
# 20200425 by zxg
 
killall -0 nginx
if [[ $? -ne 0 ]];then
  systemctl stop keepalived.service    #这个这里应该有问题，yum安装的怎么停掉服务那？
fi

# 配置备

! Configuration File for keepalived

global_defs {
   notification_email {
     
     
     
   }
   notification_email_from 
   smtp_server 192.168.200.1
   smtp_connect_timeout 30
   router_id nginx01  # router_id  唯一标识符
   vrrp_skip_check_adv_addr
   # vrrp_strict # 如果访问不了VIP就去掉，这里我注释掉了
   vrrp_garp_interval 0
   vrrp_gna_interval 0
}

vrrp_script check_nginx {  
    script "/etc/keepalived/chknginx.sh"   #nginx服务检查脚本
    interval 1
    weight -2
}

vrrp_instance VI_1 {
    state BACKUP
    interface ens33  #网卡  
    virtual_router_id 52  #默认为51  配置完发现主备切换有问题 更改为52 发现好了  原因未知
    priority 100     #主备的优先级priority 
    advert_int 1     #检查时间1秒
    authentication {
        auth_type PASS
        auth_pass 1111
    }
    track_script  {
    check_nginx
    }

    virtual_ipaddress {
        192.168.182.230/24  dev ens33 label ens33:7  #vip地址 
    }
}
}

# 重启keepalived服务

systemctl restart keepalived.service

# 测试负载均衡

访问VIP：192.168.182.230

C:\Users\29209>curl 192.168.182.230
192.168.182.130

C:\Users\29209>curl 192.168.182.230
192.168.182.131

C:\Users\29209>curl 192.168.182.230
192.168.182.130

C:\Users\29209>curl 192.168.182.230
192.168.182.131

# 测试高可用

# 停掉nginx，因为有检测脚本，自然也会停掉keepalived服务
systemctl stop nginx
# 当然也可以直接stopkeepalived服务
systemctl stop keepalived.service

# 接下来就查看VIP是否飘逸到备机器上，但是对客户而已，是没有任何影响，依旧是访问VIP
ifconfig ens33:7

~~~以上就是nginx+keepalived高可用负载均衡了~~~