环境说明：

Centos 7版本

准备Nginx的页面内容，方便观察

#nginx-2、Nginx-3和Nginx-4的Nginx的页面内容
[root@nginx-2 ~]# vim /usr/local/nginx/html/index.html 
This is 192.168.10.151
[root@nginx-3 ~]# vim /usr/local/nginx/html/index.html 
This is 192.168.10.152
[root@nginx-4 ~]# vim /usr/local/nginx/html/index.html 
This is 192.168.10.153

一、反向代理配置

[root@nginx ~]# vim /usr/local/nginx/conf/nginx.conf
worker_processes  1;
events {worker_connections  1024;
}
http {include       mime.types;default_type  application/octet-stream;sendfile        on;keepalive_timeout  65;server {listen       80;server_name  localhost;location / {
#proxy_pass就会把请求转发proxy_pass http://192.168.10.151;
#有proxy_pass，就不会访问下面的root#root   html;#index  index.html index.htm;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}
}
[root@nginx ~]# systemctl restart nginx

#验证

如果改为proxy_pass http://www.baidu.com；结果如下：

#清楚浏览器缓存，并且改为baidu.com形式，访问的是www.bai.com，也会有重定向,访问百度时，可能是因为https模式，就会有重定向，如果只是改百度的ip就会是http模式，结果如下：

二、负载均衡配置

1. 基于轮询

[root@nginx ~]# vim /usr/local/nginx/conf/nginx.conf
worker_processes  1;
events {worker_connections  1024;
}
http {include       mime.types;default_type  application/octet-stream;sendfile        on;keepalive_timeout  65;
#upstream用于配置负载均衡后端服务器的地址，合成一个组，会有一个名称，proxy_pass就会把请求转发到这个组upstream backend {server 192.168.10.151:80;server 192.168.10.152:80;
}    server {listen       80;server_name  localhost;location / {proxy_pass http://backend;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}
}
[root@nginx ~]# systemctl restart nginx

#验证

#不断刷新地址

2. 基于权重

#在轮询的基础上加上weight设置就行

[root@nginx ~]# vim /usr/local/nginx/conf/nginx.conf
worker_processes  1;
events {worker_connections  1024;
}
http {include       mime.types;default_type  application/octet-stream;sendfile        on;keepalive_timeout  65;upstream backend {server 192.168.10.151:80 weight=8;server 192.168.10.152:80 weight=6;server 192.168.10.153:80 weight=4;
}    server {listen       80;server_name  localhost;location / {proxy_pass http://backend;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}
}
[root@nginx ~]# systemctl restart nginx

#验证

down参数

#表示服务器下线，不再参与

[root@nginx ~]# vim /usr/local/nginx/conf/nginx.conf
worker_processes  1;
events {worker_connections  1024;
}
http {include       mime.types;default_type  application/octet-stream;sendfile        on;keepalive_timeout  65;upstream backend {server 192.168.10.151:80 weight=8 down;server 192.168.10.152:80 weight=6;server 192.168.10.153:80 weight=4;
}    server {listen       80;server_name  localhost;location / {proxy_pass http://backend;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}
}
[root@nginx ~]# systemctl restart nginx

#验证

backup参数

#标记一个服务器为备用服务器，当主服务器不可用时，Nginx会自动将请求到备用服务器上

[root@nginx ~]# vim /usr/local/nginx/conf/nginx.conf
worker_processes  1;
events {worker_connections  1024;
}
http {include       mime.types;default_type  application/octet-stream;sendfile        on;keepalive_timeout  65;upstream backend {server 192.168.10.151:80 weight=8 down;server 192.168.10.152:80 weight=6;server 192.168.10.153:80 weight=4 backup;
}    server {listen       80;server_name  localhost;location / {proxy_pass http://backend;}error_page   500 502 503 504  /50x.html;location = /50x.html {root   html;}}
}
[root@nginx ~]# systemctl restart nginx

#验证