I do not quite grasp how I would hook up an Nginx/Haproxy in front of my application. Would this be another application to deploy? Where does the nginx config l

I do not quite grasp how I would hook up an Nginx/Haproxy in front of my application. Would this be another application to deploy? Where does the nginx config live? Do I use consul template to update it depending on my other deployed applications? I get how you would combine a database and a web application, e.g. Rails. But what about extra routes/legacy redirects?