Nginx: rewrite port in url from reverse proxie'd app - nginx

Question

So I have set up a reverse proxy to tunnel my application.
Unfortunately the application thinks it is served via http and not https and gives out URLs with port 80.
How can I handle this in the nginx reverse proxy? (by rewriting maybe)
When I go on the page:
https://my.server.com
index.php loads, everything is okay
after clicking something I have a URL like this:
https://my.server.com:80/page/stuff/?redirect_to
which throws an error within the browser because my reverse proxy doesn't serve SSL on port 80.
How can I migitate this?
My current nginx ssl vhost for the site:
... ssl stuff ...
add_header X-Frame-Options SAMEORIGIN;
add_header X-Content-Type-Options nosniff;
location / {
proxy_pass http://localhost:22228;
proxy_buffering off;
proxy_redirect off;
proxy_read_timeout 43800;
proxy_pass_request_headers on;
proxy_set_header Connection "Keep-Alive";
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $remote_addr;
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Port 443;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_pass_header Content-Type;
proxy_pass_header Content-Disposition;
proxy_pass_header Content-Length;
proxy_set_header X-Forwarded-Proto https;
}
(yes I know my request headers look like a christmas tree 🎄)
Also bonus points if you show where the documentation addressing this issue is and what the mechanism is called.

Answer 1

For rewriting response body you can use http_sub_module:
location / {
proxy_pass http://localhost:22228;
sub_filter_once off;
sub_filter_types text/css application/javascript; # in addition to text/html
sub_filter "//my.server.com:80/" "//my.server.com/";
}
Many people says (1, 2) that you need to disable compression when using sub_filter directive:
proxy_set_header Accept-Encoding "";
For me, it works fine without this line in config, but it can be a feature of OpenResty which I use instead of nginx.
If your app generates HTTP 30x redirects with explicit indication of domain:port, you can rewrite Location header value with the proxy_redirect directive:
proxy_redirect //my.server.com:80/ //my.server.com/;