http {
  split-clients "${remote-addr}AAA" $variant {
    0.5% .one;
    2.0% .two;
    - "";
  }
 
  server {
    location / {
       index index${variant}.html;

split-clients

http {
  split_clients "${remote_addr}AAA" $variant {
    0.5% .one;
    2% .two;
    3% .eric;
    4% .yang;
    50% .thr;
    * "";
  }

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

cd /usr/local/nginx/html/

echo "one" >index.one.html
echo "two" >index.two.html
echo "eric" >index.eric.html
echo "thr" >index.thr.html

wiki : split-clients   eric:split_clients
wiki : remote-addr    eric: remote_addr
wiki : - "";      eric: * "";

log_format main '$remote_addr - $remote_user [$time_local] "$request" '
         '$status $body_bytes_sent "$http_referer" '
         '"$http_user_agent" "$http_x_forwarded_for" "$variant"';

http {
  split_clients "${remote_addr}AAA" $variant {
    0.5% .one;
    2% .two;
    * "";
  }