sample.conf

http {
    upstream str-backend {
        server 10.134.0.251:8000;  # web-worker-01
        server 10.134.13.53:8000;  # web-worker-02
        server 10.134.17.101:8000; # web-worker-03
        server 10.134.18.224:8000; # web-worker-04
        server 10.134.22.195:8000; # web-worker-05
        server 10.134.29.85:8000;  # web-worker-06
        server 10.134.33.133:8000; # web-worker-07
        server 10.134.33.183:8000; # web-worker-08
        server 10.134.33.210:8000; # web-worker-09
        server 10.134.33.216:8000; # web-worker-10
        server 10.134.34.4:8000;  # web-worker-11
        server 10.134.34.5:8000;  # web-worker-12
        server 10.134.34.6:8000;  # web-worker-13
        server 10.134.34.7:8000;  # web-worker-14
        server 10.134.34.8:8000;  # web-worker-15
        server 10.134.34.9:8000;  # web-worker-16
        server 10.134.34.10:8000; # web-worker-17
        server 10.134.34.11:8000; # web-worker-18
        server 10.134.34.12:8000; # web-worker-19
        server 10.134.34.17:8000; # web-worker-20
    }
}

server {
    location / {
        if ( -f $document_root/offline ) {
            return 503;
        }
        proxy_pass_header Server;
        proxy_set_header Host $http_host;
        proxy_redirect off;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Scheme $scheme;
        proxy_connect_timeout 30;
        proxy_read_timeout 300;
        proxy_pass http://str-backend;
    }
    # what to serve if upstream is not available or crashes
    error_page 500 502 503 504 /static/50x.html;

}