Nginx seven-layer load balancing

1. Introduction to seven-layer load balancing

NginxLayer seven load balancing is performed on the application layer (HTTP/HTTPS), which can be used according toHTTP RequestThe specific contents of the request, such as URLs, cookies, headers, etc., determine which backend server to forward the request. This method not only balances the computing load of the server, but also implements more complex routing strategies, such as:

• Sticky Sessions: Ensure that the user's session requests are always directed to the same backend server.

• Content-based routing: Distribute the request to different servers based on the requested content (such as URL, header information).

1.1 The difference between load balancing of four layers and seven layers

1.1.1 Four-layer load balancing (Layer 4 Load Balancing）

• It is performed on the Transport Layer.

• Pay attention to network-level information, such as source and destination IP addresses, port numbers, etc.

• Decide which server to forward the packet to based on network information.

• Don't check the contents of the packet in depth.

• Mainly applicable toTCP/UDP traffic such as HTTP and HTTPS.

1.1.2 Layer 7 Load Balancing

• It is done on the Application Layer.

• In-depth check of the content of network traffic, such as HTTP request headers, URLs, cookies, etc.

• Making complex routing decisions based on traffic content.

• It can handle a variety of application layer protocols, not limited to HTTP.

1.2 Layer 7 load balancing configuration

1.2.1 Backend node configuration

1.2.1.1 Static address server (static)

[root@static ~]# mkdir /nginx/static
[root@static ~]# echo "This is static page IP=`hostname -I`" >> /nginx/static/
[root@static ~]# vim /etc/nginx//
server {
        listen 192.168.110.32:80;
        server_name ,com;
        root /nginx;
​
        location / {
                index ;
        }
}
​
[root@static ~]# nginx -s reload
[root@static ~]# nginx -t
nginx: the configuration file /etc/nginx/ syntax is ok
nginx: configuration file /etc/nginx/ test is successful
[root@static ~]# curl 192.168.110.32/static/
This is static page IP=192.168.110.32 

1.2.1.2 Default address server (default)

[root@default ~]# mkdir /nginx/default
[root@default ~]# echo "This is default page IP=`hostname -I`" >> /nginx/default/
[root@default ~]# vim /etc/nginx// 
server {
        listen 192.168.110.33:80;
        server_name ,com;
        root /nginx/default;
​
        location / {
                index ;
        }
}
​
[root@default ~]# nginx -t
nginx: the configuration file /etc/nginx/ syntax is ok
nginx: configuration file /etc/nginx/ test is successful
[root@default ~]# nginx -s reload
[root@default ~]# curl 192.168.110.33/default/
This is default page IP=192.168.110.33 

1.2.1.3 Dynamic address server (upload）

[root@upload ~]# mkdir /nginx/upload
[root@upload ~]# echo "This is upload page IP=`hostname -I`" >> /nginx/upload/
[root@upload ~]# vim /etc/nginx// 
server {
        listen 192.168.110.34:80;
        server_name ,com;
        root /nginx;
​
        location / {
                index ;
        }
}
​
[root@upload ~]# nginx -t
nginx: the configuration file /etc/nginx/ syntax is ok
nginx: configuration file /etc/nginx/ test is successful
[root@upload ~]# nginx -s reload
[root@upload ~]# curl 192.168.110.34/upload/
This is upload page IP=192.168.110.34 

1.2.2 Proxy Server Configuration

[root@proxy ~]# vim /etc/nginx//
upstream static_pools {
        server 192.168.110.32;
}
​
upstream default_pools {
        server 192.168.110.33;
}
​
upstream upload_pools {
        server 192.168.110.34;
}
​
server {
        listen 80;
        server_name ;
​
        location /static {
                proxy_pass http://static_pools;
                proxy_set_header host $host;
                proxy_set_header X-Forwarded-For $remote_addr;
        }
​
        location /default {
                proxy_pass http://default_pools;
                proxy_set_header host $host;
                proxy_set_header X-Forwarded-For $remote_addr;
        }
​
        location /upload {
                proxy_pass http://upload_pools;
                proxy_set_header host $host;
                proxy_set_header X-Forwarded-For $remote_addr;
        }
}
​
[root@proxy ~]# nginx -t
nginx: the configuration file /etc/nginx/ syntax is ok
nginx: configuration file /etc/nginx/ test is successful
[root@proxy ~]# nginx -s reload

Note: The main difficulty here is the way to write location. For example: If the site directory writes root /nginx/ststic; then the last access/static/The forwarding path is/static/static. So just write /nginx

1.2.3 Client test access

[root@client ~]# echo '192.168.110.31 ' >> /etc/hosts
[root@client ~]# curl 
This is default page IP=192.168.110.33 
[root@client ~]# curl /static/
This is static page IP=192.168.110.32 
[root@client ~]# curl /upload/
This is upload page IP=192.168.110.34 

1.2.4 View access logs of each node

[root@static ~]# tail -1 /var/log/nginx/
192.168.110.31 - - [21/Apr/2024:17:07:34 +0800] "GET /static/ HTTP/1.0" 200 39 "-" "curl/7.61.1" "192.168.110.35"
​
[root@default ~]# tail -1 /var/log/nginx/
192.168.110.31 - - [21/Apr/2024:17:07:32 +0800] "GET / HTTP/1.0" 200 40 "-" "curl/7.61.1" "192.168.110.35"
​
[root@upload ~]# tail -1 /var/log/nginx/
192.168.110.31 - - [21/Apr/2024:17:07:36 +0800] "GET /upload/ HTTP/1.0" 200 39 "-" "curl/7.61.1" "192.168.110.35"