For example:

mydomain.com/site1
mydomain.com/site2

I need to install an application on /site1 that will think that it is on the root folder. (In this case PHP, js, CodeIgniter, but could be anything)

So for example, links/references for files such as "/file.jpg" (in code that is in the site1 folder, such as at mydomain.com/site1/code.js) will really load from mydomain.com/site1/file.jpg And also the code would not be able to see any folder below site1, so that is basically the root folder. And similar thing would be at site2, so the 2 are separate root folders.

I thought this would be some kind of simple .htaccess file installed at mydomain.com/site1 with a redirect, or some kind of a reverse proxy, but so far everything I tried did not work. I can't seem to find even any such example even on stack overflow.. Any ideas?

CodePudding user response：

The easiest way to do this would be to create an additional VirtualHost, for internal use, called internal1, whose RootDirectory is, you guessed it, /var/www/mydomain.com/htdocs/site1 where the main site is in /var/www/mydomain.com/htdocs.

Then in mydomain.com you reverse proxy /site1 to internal1 (you'll have to put it into /etc/hosts and alias for localhost). The second request will have its DOCUMENT_ROOT point to site1, as requested (and its ServerName changed to internal1):

ProxyPass        /site1/   http://internal1/
ProxyPassReverse /site1/   http://internal1/

(Not sure about the trailing slashes)

Now, accessing yourdomain.com/site1/joe.html will trigger a second internal connection to internal1/joe.html, which will contain, say, 'src="/joe.jpg"'; and here's where ProxyPassReverse will come into play, rewriting this in 'src="yourdomain.com/site1/joe.jpg"' so that everything will work.

errata corrige

The above is not correct, thanks @MrWhite for pointing this out. ProxyPassReverse is not enough as it only rewrites headers. From the Apache documentation (emphasis mine):

Only the HTTP response headers specifically mentioned above will be rewritten. Apache httpd will not rewrite other response headers, nor will it by default rewrite URL references inside HTML pages. This means that if the proxied content contains absolute URL references, they will bypass the proxy. To rewrite HTML content to match the proxy, you must load and enable mod_proxy_html.

(The method is dirty as all Hell: every HTTP call incurs one extra connection and two rewrites, one going in, a larger one going out).

Of course, if the link is built using e.g. Javascript, it might well be that the proxy code will not recognize it as a link, will leave it unchanged, maybe with the "internal1" name inside somewhere, and the app will break.

However, @arkascha has the right of it - you should cure the cause, not the symptom. You can maybe rewrite the environment of the apps so that they run without troubles even if they are in a subdirectory. Or you could try injecting <base href="https://example.com/site1"> in the output HTML.