The ngx_http_split_clients_module module creates variables suitable for A/B testing, also known as split testing.

http {
    split_clients "${remote_addr}AAA" $variant {
                   0.5%               .one;
                   2.0%               .two;
                   *                  "";
    }

    server {
        location / {
            index index${variant}.html;

Creates a variable for A/B testing, for example:

split_clients "${remote_addr}AAA" $variant {
               0.5%               .one;
               2.0%               .two;
               *                  "";
}

The value of the original string is hashed using MurmurHash2. In the example given, hash values from 0 to 21474835 (0.5%) correspond to the $variant variable taking the value ".one", hash values from 21474836 to 107374180 (2%) correspond to the value ".two", and hash values from 107374181 to 4294967295 correspond to the value "".