upstream backend_server {
    server   192.168.8.43:80 weight=1 max_fails=2 fail_timeout=30s;
    server   192.168.8.44:80 weight=1 max_fails=2 fail_timeout=30s;
    server   192.168.8.45:80 weight=1 max_fails=2 fail_timeout=30s;

proxy_pass http://backend_server;