Ngxin作为一个强大的开源软件是可以先做为高可用集群服务的，这篇博文就介绍一下nginx+Keepalived是如何实现高性能+高可用集群服务的

环境介绍：

   硬件：    4台虚拟服务器

   系统：CentOS 7.3

   软件：Keepalived、Apache、Nginx

IP及主机名

   Master

       主机名：shiyan1

       IP地址：172.18.17.31

   Backup

       主机名：shiyan2

       IP地址：172.18.17.32

   Httpd1

       主机名：shiyan3

       IP地址：172.18.17.33

   Httpd2

       主机名：shiyan4

       IP地址：172.18.17.34

四台服务器初始化配置(四台服务器相同的配置)

   关闭防火墙

    [root@shiyan~ ]# systemctl disable firewalld
    [root@shiyan~ ]# systemctl stop firewalld
    [root@shiyan~ ]# iptables –F

  关闭Selinux

    [root@shiyan~ ]# vim /etc/selinux/config
       SELINUX=disabled
     #保存重启系统生效

   安装软件

     Master/Backup

    [root@shiyan~ ]# yum install keepalived httpd nginx   #(Nginx需要单独配置EPEL源)

     Httpd1/Httpd2

        [root@shiyan~ ]# yum install httpd

Httpd1配置

    [root@shiyan3 ~ ]# mkdir -p /app/apache/html/  
    [root@shiyan3 ~ ]# chown -R apache.apache /app/apache/html/
    [root@shiyan3 ~ ]# echo "Apache Server 1" > /app/apache/html/index.html
    [root@shiyan3 ~ ]# vim /etc/httpd/conf/httpd.conf 
          #此处是更改httpd.conf中的内容，并非添加内容
       DocumentRoot "/app/apache/html"    
       #更改为自定义的路径
            
       #
       # Relax access to content within /var/www.
       #
           #更改为自定义的路径
       AllowOverride None
       # Allow open access:
       Require all granted
       
            
       # Further relax access to the default document root:
            #更改为自定义的路径.
     [root@shiyan3 ~ ]# systemctl restart httpd
     
     #测试网站是否正常运行
     [root@yum ~ ]# curl http://172.18.17.33
            Apache Server 1  #测试成功

Httpd2配置

    [root@shiyan4 ~ ]# mkdir -p /app/apache/html/  
    [root@shiyan4 ~ ]# chown -R apache.apache /app/apache/html/
    [root@shiyan4 ~ ]# echo "Apache Server 2" > /app/apache/html/index.html
    [root@shiyan4 ~ ]# vim /etc/httpd/conf/httpd.conf 
          #此处是更改httpd.conf中的内容，并非添加内容
       DocumentRoot "/app/apache/html"    
       #更改为自定义的路径
            
       #
       # Relax access to content within /var/www.
       #
           #更改为自定义的路径
       AllowOverride None
       # Allow open access:
       Require all granted
       
            
       # Further relax access to the default document root:
            #更改为自定义的路径.
    [root@shiyan4 ~ ]# systemctl restart httpd
          #测试网站是否正常运行
        [root@yum ~ ]# curl http://172.18.17.34
            Apache Server 2  #测试成功

Master配置

   配置Sorry-Server
    [root@shiyan1 ~ ]# mkdir -p /app/apache/html/  
    [root@shiyan1 ~ ]# chown -R apache.apache /app/apache/html/
    [root@shiyan1 ~ ]# echo "
Sorry Server 1
" > /app/apache/html/index.html
    [root@shiyan1 ~ ]# vim /etc/httpd/conf/httpd.conf 
       #此处是更改httpd.conf中的内容，并非添加内容
       Listen 8080
       DocumentRoot "/app/apache/html"    
       #更改为自定义的路径
            
       #
       # Relax access to content within /var/www.
       #
           #更改为自定义的路径
       AllowOverride None
       # Allow open access:
       Require all granted
       
            
       # Further relax access to the default document root:
            #更改为自定义的路径.
    [root@shiyan1 ~ ]# systemctl restart http
               #测试网站是否正常运行
        [root@yum ~ ]# curl http://172.18.17.31:8080
              
Sorry Server 1
  #测试成功
      配置Keepalived
           [root@shiyan1 ~ ]# cp /etc/keepalived/keepalived.conf{,.bak}    #备份文件
           [root@shiyan1 ~ ]# vim /etc/keepalived/keepalived.conf
              global_defs {
               notification_email {
                  root   #定义收邮件的用户
               }
               notification_email_from Alexandre.Cassen@firewall.loc
               smtp_server 172.18.17.31   #定义邮件地址
               smtp_connect_timeout 30
               router_id node1            #定义节点名称
            }
            
            vrrp_instance VI_1 {
                state MASTER              #定义节点为主节点模式
                interface ens33           #定义使用ens33为VIP网卡
                virtual_router_id 51      #定义节点编号
                priority 150              #定义优先级
                advert_int 1   
                authentication {
                    auth_type PASS
                    auth_pass 1111
                }
                virtual_ipaddress {
                    172.18.17.30          #定义VIP
                }
            }
~      配置Nginx服务
            [root@shiyan1 ~ ]# vim /etc/nginx/nginx.conf
                #添加nginx集群
                upstream websrvs {
                    server 172.18.17.33:80;
                    server 172.18.17.34:80;
                    server 127.0.0.1:8080 backup;
                }
                #server 部分的内容需要全部注释掉
                
            [root@shiyan1 ~ ]# vim /etc/nginx/conf.d/default.conf 
                    server {
                    listen       80;
                    location / {
                        root  html;
                        proxy_pass http://websrvs;
                        index  index.html index.htm;
                    }
                }
            [root@shiyan1 ~ ]# systemctl restart nginx
            [root@shiyan1 ~ ]# systemctl restart keepalived
            [root@shiyan1 ~ ]# systemctl restart httpd

Backup配置

   配置Sorry-Server
    [root@shiyan2 ~ ]# mkdir -p /app/apache/html/  
    [root@shiyan2 ~ ]# chown -R apache.apache /app/apache/html/
    [root@shiyan2 ~ ]# echo "
Sorry Server 2
" > /app/apache/html/index.html
    [root@shiyan2 ~ ]# vim /etc/httpd/conf/httpd.conf 
       #此处是更改httpd.conf中的内容，并非添加内容
       Listen 8080
       DocumentRoot "/app/apache/html"    
       #更改为自定义的路径
            
       #
       # Relax access to content within /var/www.
       #
           #更改为自定义的路径
       AllowOverride None
       # Allow open access:
       Require all granted
       
            
       # Further relax access to the default document root:
            #更改为自定义的路径.
    [root@shiyan2 ~ ]# systemctl restart http
               #测试网站是否正常运行
        [root@yum ~ ]# curl http://172.18.17.31:8080
              
Sorry Server 2
  #测试成功
   配置Keepalived
     [root@shiyan2 ~ ]# cp /etc/keepalived/keepalived.conf{,.bak}    #备份文件
     [root@shiyan2 ~ ]# vim /etc/keepalived/keepalived.conf
              global_defs {
               notification_email {
                  root   #定义收邮件的用户
               }
               notification_email_from Alexandre.Cassen@firewall.loc
               smtp_server 172.18.17.31   #定义邮件地址
               smtp_connect_timeout 30
               router_id node1            #定义节点名称
            }
            
            vrrp_instance VI_1 {
                state MASTER              #定义节点为主节点模式
                interface ens33           #定义使用ens33为VIP网卡
                virtual_router_id 51      #定义节点编号
                priority 150              #定义优先级
                advert_int 1   
                authentication {
                    auth_type PASS
                    auth_pass 1111
                }
                virtual_ipaddress {
                    172.18.17.30          #定义VIP
                }
            }
~  配置Nginx服务
      [root@shiyan2 ~ ]# vim /etc/nginx/nginx.conf
         #添加nginx集群
          upstream websrvs {
           server 172.18.17.33:80;
           server 172.18.17.34:80;
           server 127.0.0.1:8080 backup;
           }
           #server 部分的内容需要全部注释掉
                    
      [root@shiyan2 ~ ]# vim /etc/nginx/conf.d/default.conf 
           server {
           listen       80;
           location / {
           root  html;
           proxy_pass http://websrvs;
           index  index.html index.htm;
           } 
          }
       [root@shiyan2 ~ ]# systemctl restart keepalived
       [root@shiyan2 ~ ]# systemctl restart nginx
       [root@shiyan2 ~ ]# systemctl restart httpd

测试环境    

 #默认使用rr算法依次轮询访问后端httpd服务器
    [root@yum ~ ]# curl http://172.18.17.30    
    Apache Server 1
    [root@yum ~ ]# curl http://172.18.17.30
    Apache Server 2
 
 #关闭后端http1服务，这样只能访问httpd2的服务
     [root@yum ~ ]# curl http://172.18.17.30
      Apache Server 2
     [root@yum ~ ]# curl http://172.18.17.30
      Apache Server 2
      
 #关闭两台后端主机的httpd服务，这样因为没有后端服务器所以Master的sorry-server提供服务
    [root@yum ~ ]# curl http://172.18.17.30
    
Sorry Server 1
 #关闭Master测试
    [root@yum ~ ]# curl http://172.18.17.30
    
Sorry Server 2