Nginx reverse proxy for Heroku

nginx_reverse_proxy.conf

upstream heroku {
        server myapp.herokuapp.com;
}

server {
        server_name ~^(www\.)(?<domain>.+)$;
        return 301 $scheme://$domain$request_uri;
}

server {
        listen 80 default;
        listen 443 ssl;
        #server_name _;

        ssl off;
        ssl_certificate /etc/nginx/ssl/myapp.com.crt;
        ssl_certificate_key /etc/nginx/ssl/myapp.com.key;

        location ~ \.php$ {
                return 444;
        }

        location / {
                proxy_pass http://heroku;
                proxy_redirect off;
                proxy_read_timeout 5m;
                proxy_set_header Host $http_host;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-Proto http;
        }
}

This is so you can use a custom domain with an A record as apposed to an ALIAS or CNAME. This can be helpful when building a product that allows an end user to map their own custom domain. An A record is much easier for them to do (and doesn't force www.)

I'm trying to serve two nodejs apps on Heroku.
One on app.example.com and one on example.com.
I setup the DNS via cloudflare correctly (but I've used CNAME).
I've added nginx from https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-nginx
I'm stuck with configuring the nginx file (first time when touching it). I feel that I'm close, but I'm not sure where to place this code, as yours.

@george-i As per the link :

You can provide your own NGINX config by creating a file named nginx.conf.erb in the config directory of your app