Dynamic directory alias with Apach 2.4

Question

I'm wondering if it's possible to create a dynamic directory alias based on the requested subdomain.

If a user requests the URL https://{subdomain}.site.com/images/ I would like the file system folder /full/linux/path/to/{subdomain}/images/ to be served (not necessarily under the document root).

Tried

<VirtualHost *:80>
  ServerAlias *.domain.com
  DocumentRoot /var/www/domain.com
  Alias /images/ /path/to/%1/images/
</VirtualHost>

And

<VirtualHost *:80>
  ServerAlias *.domain.com
  DocumentRoot /var/www/domain.com
  SetEnvIf Host "^([^.]*)\." SUBDOMAIN=$1
  Alias /storage/ /path/to/%{ENV:SUBDOMAIN}/images/"
</VirtualHost>

Answer 1

Since you consider my comment to the question "pointless" I will help you out...

Apache's Alias directive operates on paths, but rewriting easily allows what you are looking for:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^([^.]+)\.example\.com$
RewriteRule ^/?images/(.*)$ /path/to/%1/images/$1 [QSA,END]

In case you receive an internal server error (http status 500) using the rule above then chances are that you operate a very old version of the apache http server. You will see a definite hint to an unsupported [END] flag in your http servers error log file in that case. You can either try to upgrade or use the older [L] flag, it probably will work the same in this situation, though that depends a bit on your setup.

This implementation will work likewise in the http servers host configuration or inside a distributed configuration file (".htaccess" file). Obviously the rewriting module needs to be loaded inside the http server and enabled in the http host. In case you use a distributed configuration file you need to take care that it's interpretation is enabled at all in the host configuration and that it is located in the host's DOCUMENT_ROOT folder.

And a general remark: you should always prefer to place such rules in the http servers host configuration instead of using distributed configuration files (".htaccess"). Those distributed configuration files add complexity, are often a cause of unexpected behavior, hard to debug and they really slow down the http server. They are only provided as a last option for situations where you do not have access to the real http servers host configuration (read: really cheap service providers) or for applications insisting on writing their own rules (which is an obvious security nightmare).

---

And to come back to my initial comment to your question here is a spontaneous collection of existing answers here on SO demonstrating the same thing:

• Apache Rewrite: image directory based on HTTP host
• .htaccess rewrite subdomain to directory
• htaccess subdomain rewrite
• Apache rewrite based on subdomain
• URL/Subdomain rewrite (htaccess)
• ...