Apache dynamic wildcard host rewrite with dynamic subdomains - apache

Question

I'm currently in the process of converting an old apache vhost, where one is currently created for each new release, to a dynamic host that can handle all the subdomains so we don't have to create a new one all the time. I need some help! We're using apache v2.2.
The Goal
Dynamic all the things. To have a single virtual host that handles all redirects for a specific set of subdomains. The url is below, note that sub1 and branch are dynamic and could be anything.
sub1.branch.sandbox.domain.com
The directory structure for this is as follows:
/var/www/vhosts/branch/sub1.branch.sandbox.domain.com
As you can see above, the directory structure has the branch as a sub-directory before the full url is the name of another sub-directory.
Also, /images/ in the url needs to forward to shared-httpdocs/images for each domain.
The vhost I have so far
<VirtualHost *:80>
ServerName branch.sandbox.domain.com
ServerAlias *.branch.sandbox.domain.com
VirtualDocumentRoot /var/www/vhosts/branch/%0
Options Indexes FollowSymLinks
# Rewrite Engine Stuff Here
RewriteEngine On
DirectoryIndex index.php
# Assets needs to be forwarded - currently not working
RewriteCond %{REQUEST_URI} ^/(css|js|images)/.*
RewriteRule .*$ /var/www/vhosts/%0/shared-httpdocs/%1$ [L]
# The HTTP dispatcher - currently not working
RewriteCond %{HTTP_HOST} ^(.*)\.branch\.sandbox\.domain\.com [NC]
RewriteRule ^(.*)$ /var/www/vhosts/%1/applications/portal/dispatchers/http.php [L,QSA,NS,NE,NC]
</VirtualHost>
The old host I'm trying to copy
This is the old vhost I'm trying to convert from. It's horrible, messy, and our ops has to create a new DNS entry every time. What a joke! I need to sort this out...
<VirtualHost *:80>
# Notice how the stupid convention below will require a new DNS entry each time?
ServerName sandbox.branch.domain.com
ServerAlias sandbox.api.branch.domain.com
DocumentRoot /var/www/vhosts/sandbox.branch.domain.com/applications/portal/httpdocs
<Directory "/var/www/vhosts/sandbox.branch.domain.com/applications/portal/httpdocs">
allow from all
order allow,deny
# Enables .htaccess files for this site
#AllowOverride All
RewriteEngine On
# Rewrite all non-static requests to go through the webapp
RewriteCond %{REQUEST_URI} ^/(css|js|images)/.*
RewriteRule .* - [L]
# Rewrite everything else to go through the webapp
RewriteRule ^(.*)$ /dispatchers/http.php [QSA,L]
</Directory>
<Directory "/var/www/vhosts/sandbox.branch.domain.com/applications/portal/dispatchers">
allow from all
</Directory>
# Allow us to rewrite to the webapp without it being in the webroot
Alias /dispatchers /var/www/vhosts/sandbox.branch.domain.com/applications/portal/dispatchers
# Get shared/ to point to the shared static resources
Alias /shared /var/www/vhosts/sandbox.branch.domain.com/shared-httpdocs
</VirtualHost>
A new DNS entry is required each time we have a new branch, so I'm trying to mitigate this by providing a dynamic subdomain vhost (see the vhost I have so far). I've gone from not even being able to match /images/ in the url to a permanent redirect loop.
How can I achieve my goal? I know it's a little complex. If I can't do it, I'll just have to write a script that will generate a new vhost each time but a dynamic one that 'just works' would be fantastic. I've put two days into this so far, I'm no sysadmin. Your help would be greatly appreciated.
Resources I have been using:
mod_rewrite official docs - Shows the basics like things on conditions with REWRITE_COND
Sub domain rewriting - A question on subdomain rewriting
Asset rewriting - Another question on rewriting things like images / css / js, which doesn't seem to work for me

Answer 1

It's not a complete answer, but is too long for comment.
The %0 (%0 to %9) in a rewrite rule are back references to captures in the last RewriteCond. It seems to me you wanted instead the host name. Also it seems you miss the "branch" part of the path. In the Asset's rewrite you also throw away the filename part.
# Assets needs to be forwarded - currently not working
RewriteCond %{REQUEST_URI} ^/(css|js|images)/(.*)
RewriteRule .*$ /var/www/vhosts/branch/%{HTTP_HOST}/shared-httpdocs/%1/%2$ [L]
# The HTTP dispatcher - currently not working
RewriteCond %{HTTP_HOST} ^(.*)\.branch\.sandbox\.domain\.com [NC]
RewriteRule ^(.*)$ /var/www/vhosts/branch/%{HTTP_HOST}/applications/portal/dispatchers/http.php [L,QSA,NS,NE,NC]
You can get debugging help also from mod_rewrite dedicated logging with RewriteLog and RewriteLogLevel directives.
Hope this will bring you further.