Unable to map upstream with folder in nginx server

I want to map our system port 82 with 127.0.0.1:8080/runningSite and I am gettting exception with nginx config.

upstream dev {
    server 127.0.0.1:8080/runningSite;
}
server {
    rewrite_log on;
    listen [::]:81;
    server_name localhost;

    location / {
        proxy_pass  http://dev;
        proxy_set_header Host $http_host;
    }

}

Exception :

nginx: [emerg] invalid host in upstream "127.0.0.1:8080/runningSite" in C:\nginx -1.8.1/conf/nginx.conf:85

Can anyone please help me where I am wrong.