nginx.conf

user  nginx;
worker_processes  1;

error_log  /var/log/nginx/error.log warn;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    map $http_upgrade $connection_upgrade {
        default upgrade;
        '' close;
    }

    upstream websocket {
        server 127.0.0.1:8000;
        server 127.0.0.1:8001;
        server 127.0.0.1:8002;
        server 127.0.0.1:8003;
        server 127.0.0.1:8004;
        server 127.0.0.1:8005;
        server 127.0.0.1:8006;
        server 127.0.0.1:8007;
        server 127.0.0.1:8008;
        server 127.0.0.1:8009;
    }

    server {
        listen 9000;
        location / {
            proxy_pass http://websocket;
            proxy_http_version 1.1;
            proxy_read_timeout 500ms;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;
        }
    }
}