nginx websocket proxying

server {
        ...

        location /chat/ {
            proxy_pass http://backend;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection $connection_upgrade;
        }
    }

官方关于websocket proxying的文档：http://nginx.org/en/docs/http/websocket.html