Transparent reverse proxy written in PHP that allows you to not have to write PHP any more.

This short, single-file, 130-line PHP script is a simple and fully transparent HTTP(S) reverse proxy written in PHP that allows you to never have to use PHP again for a new project, if you feel so inclined, for example if you are forced to host on a fully 3rd-party-managed server where you can't do more than run PHP and upload files via FTP. The PHP script simply reads all requests from a browser pointed to it, forwards them (via PHP's curl library) to a web application listening at another URL (e.g. on a more powerful, more secure, more private, or more capable server in a different data center), and returns the responses transparently and unmodified.

Supports:

• Regular and XMLHttpRequests (AJAX)
• All HTTP headers without discrimination
• GET and POST verbs
• Content types (HTTP payload) without discrimination
• Redirects (internal redirects are rewritten to relative URIs)
• Multipart content type
• Cookies (with conversion of the backend domain to the no.php host)

Does not support (or not tested):

• HTTP verbs other than GET and POST (but these are usually emulated anyway)
• HTTP greater than version 1.1 (e.g. reusable connections)
• Upgrade to websocket (persistent connections)

You have a non-PHP web application (called the "backend") listening on https://myapp.backend.com:3000 but due to constraints you must make it available on a shared hosting server called https://example.com/subdir which only supports PHP and can't be configured at all. On latter server, Apache (or Nginx, doesn't matter) will usually do the following:

1. If a URI points to a .php file, this file will be interpreted
2. If a URI points to a file that is not existing, a 404 status will be returned.

Using no.php, to accomodate the second case, all URIs of the proxied web app (including static files) must be appended to the URI https://example.com/subdir/no.php. For example:

https://example.com/subdir/no.php/images/image.png
https://example.com/subdir/no.php/people/15/edit

If your backend app supports that extra /subdir/no.php prefix to all paths, you are all set and ready to use no.php. Then:

1. Simply copy no.php into the subdir directory of example.com
2. Change $backend_url in no.php to "https://myapp.backend.com:3000"
3. Point a browser to https://example.com/subdir/no.php

In Ruby on Rails for example you must do a minimal adaptation to facilitate the mentioned URL prefix -- please consult the Ruby on Rails documentation for full details, but here is a hint:

ENV['RAILS_RELATIVE_URL_ROOT'] = "/subdir/no.php"

Rails.application.configure do
  config.relative_url_root = ENV['RAILS_RELATIVE_URL_ROOT']
end

Rails.application.routes.draw do
  scope path: ENV['RAILS_RELATIVE_URL_ROOT'] do
    # routes here
  end
end