gemini.conf

stream {

    ###
    ### Setup
    ###

    # connection-limiting
    limit_conn_zone               $binary_remote_addr zone=addr:10m;
    limit_conn_log_level          warn;
    limit_conn                    addr 1;

    # logging
    log_format                    basic '$remote_addr $upstream_addr [$time_local] '
                                  '$protocol $status $bytes_sent $bytes_received '
                                  '$session_time';
    access_log                    syslog:server=unix:/dev/log basic;
    error_log                     stderr;

    # map SNI -> backend service
    map $ssl_preread_server_name  $name {
        your.domain.name     backend_1;
    }


    ###
    ### Frontends
    ###

    # Gemini
    server {
        listen                    1965;
        ssl_preread               on;
        proxy_buffer_size         16k;

        # pass requests directly to the corresponding Gemini server
        proxy_pass                $name;
    }


    ###
    ### Backends
    ###

    # one of your capsules
    upstream backend_1 {
        server                    127.0.0.1:1990;
    }
}