Upstream: ngx_http_upstream_random module.

Upstream: ngx_http_upstream_random module.

The module implements random load-balancing algorithm with optional second
choice.  In the latter case, the best of two servers is chosen, accounting
number of connections and server weight.

Example:

upstream u {
    random [two [least_conn]];

    server 127.0.0.1:8080;
    server 127.0.0.1:8081;
    server 127.0.0.1:8082;
    server 127.0.0.1:8083;
}