Synopsis

ngx_http_split_clients_module is used to split clients based on some conditions(e.g ip addresses, headers, cookies, etc).

Examples

Basic configuration:

http {
    split_clients "${remote_addr}AAA" $variant {
        40.5% ".one";
        59.5% ".two";
    }
 
    server {
        location / {
             index index${variant}.html;
        [...]
    }

On the example configuration above, the input for calculating the percentage is the variable plus string ("${remote_addr}AAA"). This string will be converted into a percentage value using MurmurHash2, the result will be compared to the directives and fill the $variant variable with the value just after the percentage in the configuration directives.

Instead of ${remote_addr}, one could use ${cookie}, ${args} or another nginx variable. You may also add a salt (arbitrary string) if needed.

• Keep in mind that if you use a variable like ${remote_addr} (user IP), the hash (and percentage) will always be the same as long as the user/client keep the same IP. In other words, the $variant value will always be the same for the same IP.
• Hashing algorithm is MurmurHash since version 1.0.1; Previously CRC32.

Sending a query string variable to 51% of clients (to PHP scripts)

http {
    split_clients "${remote_addr}" $additionalQsVariable {
	    51% "coolVariable=1";
	    49% "";
	}
 
    server {
        location ~ \.php$ {
            set $args "${query_string}&${$additionalQsVariable}";
            [...]
        }
    }

Directives

split_clients

References

• Original Documentation
• Naming convention discussion