The geo module in Nginx and how to use it to configure load balancing

The geo directive uses the ngx_http_geo_module module. By default, nginx loads this module unless --without-http_geo_module is configured manually.
ngx_http_geo_module module can be used to create variables whose values ​​depend on the client ip address.
geo directive
Syntax: geo [$address] $variable { ... }
Default value: —
Configuration section: http
Definition from the specified variable Get the client's ip address. By default, nginx gets the client IP address from the $remote_addr variable, but it can also be obtained from other variables. For example,

geo $remote_addr $geo {
    default 0;
    127.0.0.1 1;
}
geo $arg_ttlsa_com $geo {
    default 0;
    127.0.0.1 1;
}

If the value of this variable cannot represent a legal IP address, then nginx will use the address "255.255.255.255".
nginx describes the address through cidr or address segment, and supports the following parameters:

• delete: delete the specified network

• if If the client address cannot match any defined address, nginx will use the default value. CIDR can use "0.0.0.0/0" to replace the default value.

• include: Contains a file that defines addresses and values, and can contain multiple files.

• proxy: Define trusted address. When the request comes from a trusted address, nginx will obtain the address information with the help of its "X-Forwarded-For" header. Compared with ordinary addresses, trusted addresses are detected sequentially.

• proxy_recursive: Enable recursive address search. If recursive lookup is turned off, nginx will use the last address in "x-forwarded-for" instead of the original client address when the client address matches a trusted address. If recursive search is enabled, when the client address matches a trusted address, nginx will use the last address in "x-forwarded-for" that does not match any trusted address to replace the original client address.

• ranges: Define the address in the form of an address segment. This parameter must be placed first. To speed up loading of the address library, addresses should be defined in ascending order.

geo $country {
  default    zz;
  include    conf/geo.conf;
  delete     127.0.0.0/16;
  proxy     192.168.100.0/24;
  proxy     2001:0db8::/32;
 
  127.0.0.0/24  us;
  127.0.0.1/32  ru;
  10.1.0.0/16  ru;
  192.168.1.0/24 uk;
}

vim conf/geo.conf

10.2.0.0/16  ru;
192.168.2.0/24 ru;

Address segment example:

geo $country {
  ranges;
  default          zz;
  127.0.0.0-127.0.0.0    us;
  127.0.0.1-127.0.0.1    ru;
  127.0.0.1-127.0.0.255   us;
  10.1.0.0-10.1.255.255   ru;
  192.168.1.0-192.168.1.255 uk;
}

The geo command mainly assigns values ​​to variables based on ip. Therefore, only IP or network segments can be defined under the geo block, otherwise an error will be reported.

geo module implements global load balancing
server1 : 192.168.6.101
server2 : 192.168.6.102
server3 : 192.168.6.121

Test machine 1 ip: 192.168.6.2
Test machine 2 ip: 192.168.6.8
Test machine 3 ip: 192.168.6.189

1. Compile and install nginx on each server, I don’t have much said!
I have not changed the configurations of server1 and server2. I only changed the homepage, which is good for testing!
server1 :

shell $> cd /usr/local/nginx/html
shell $> rm index.html
shell $> echo "192.168.6.101" > index.html

server2:

shell $> cd /usr/local/nginx/html
shell $> rm index.html
shell $> echo "192.168.6.102" > index.html

Get their services up

shell $> /usr/local/nginx/sbin/nginx

2 .Modify the configuration of server3`

shell $> cd /usr/local/nginx/conf/
shell $> vim nginx.conf

worker_processes 1;
 
events {
  worker_connections 1024;
}
http {
  include    mime.types;
  default_type application/octet-stream;
  geo $geo {
    default default;
    192.168.6.189/32    uk;
    192.168.6.8/32     us;
#这里的子网码是 32 是因为，我是单网段测试，如果你有vlan，你可以是24 例如
# 192.168.0.0/24   tw
  }
  upstream  uk.server {
    server 192.168.6.101;
  }
  upstream  us.server {
    server 192.168.6.102;
  }
  upstream  default.server {
    server 192.168.6.121:8080;
  }
  sendfile    on;
  keepalive_timeout 65;

  server {
    listen    80;
    server_name 192.168.6.121;
    index index.html index.htm;
    root html;

    location / {
        proxy_redirect off;
        proxy_set_header host $host;
        proxy_set_header x-real-ip $remote_addr;
        proxy_set_header x-forwarded-for $proxy_add_x_forwarded_for;
        proxy_pass http://$geo.server$request_uri;
    }
    error_page  500 502 503 504 /50x.html;
    location = /50x.html {
      root  html;
    }
 
  }
 
  server {
    listen    8080;
    server_name 192.168.6.121;
    location / {
      root  html;
      index index.html index.htm;
    }
  }
}

3. Test, open the browser on test machine 1 and enter
http://192.168.6.121
display

Because the IP address of test machine 1 is 192.168.6.2 according to nginx configuration, it is obvious that he accesses server3 port 8080! Because I modified the index.html of server1 server2

Open the browser on test machine 2~Enter
http://192.168.6.121
display

Open the browser on test machine 3 ~ enter
http://192.168.6.121
The ip of test machine 3 is 192.168.6.189
Display:

Obviously, load balancing plays a role~~~
In this way, the three servers can be placed in different IDC computer rooms. Then just synchronize the data~ The advantage of this is that it saves the trouble with DNS, because smart DNS will sometimes parse the other party's DNS address when parsing according to the visiting IP, and match it to a server. If the other party He is a Netcom user. The Telecom DNS he uses will directly match him to the Telecom server, nginx, and match the server based on the access IP. In this way, as long as we collect the IP segments in each region, it will be fine.

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