Running docker app on my domain using nginx reverse proxy

I have a docker app and it works on http:// localhost:8000. This app also works on http://my_domain.com. I would like to run my docker app through nginx reverse proxy. Therefore, I have done the following.

$ docker run -d --rm -p 8000:8000 my_app

$ curl http://localhost:8000 

$ sudo nano /etc/nginx/sites-available/my_domain.com

The file my_domain.com contains the following:

server {
    server_name  my_domain.com;
    index index.html index.htm;
    access_log /var/log/nginx/my_app.log;
    error_log  /var/log/nginx/my_app-error.log error;

    location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $http_host;
        proxy_pass http://127.0.0.1:8000;
        proxy_redirect off;
    }
}

Then, I have written the following on the command line:

$ sudo ln -s /etc/nginx/sites-available/my_domain.com /etc/nginx/sites-enabled/my_domain.com

$ sudo nginx -t

$ sudo nginx -s reload

Everything seems ok, but when I visit http://my_domain.com, I see the nginx default page with: Welcome to nginx! Unfortunately, I cannot see my app running as I saw on http:// localhost:8000 or on http://my_domain.com before the above operation.