I'm getting 404 / apache error issues while trying to configure multiple stores having the same domain name and specific URI "directory"

What I have done

vhost config

NameVirtualHost *:80
<VirtualHost *:80>
 DocumentRoot "/var/www/html/dev-site/code"
 ServerName my.domain.local

 Alias /alias1 /var/www/html/dev-site/code
 Alias /alias2 /var/www/html/dev-site/code
 Alias /alias3 /var/www/html/dev-site/code

 <Directory /var/www/html/dev-site/code>
 Order allow,deny
 Allow from all
 AllowOverride All
 RewriteEngine On
 Options +FollowSymlinks
 </Directory>

 SetEnvIf Request_URI ^/alias1(.*) MAGE_RUN_CODE=pf_view
 SetEnvIf Request_URI ^/alias1(.*) MAGE_RUN_TYPE=store

 SetEnvIf Request_URI ^/alias2(.*) MAGE_RUN_CODE=es_view
 SetEnvIf Request_URI ^/alias2(.*) MAGE_RUN_TYPE=store

 SetEnvIf Request_URI ^/alias3(.*) MAGE_RUN_CODE=ta_view
 SetEnvIf Request_URI ^/alias3(.*) MAGE_RUN_TYPE=store
</VirtualHost>

Magento config

• In core_config_data, default base_url is set to "http://domain.local/" (so we can access admin at http://domain.local/admin)


• Each store base_url is set as "http://my.domain.local/aliasX/" (replace X by 1, 2 or 3)


• Every single js/media/skin base url is explicitely specified and common for all aliases (e.g. http://my.domain.local/js/)


• 
  

  index.php is tweaked so it can handle "REDIRECT_" server vars :

  
  
  

  /* Store or website code */
  $mageRunCode = isset($_SERVER['MAGE_RUN_CODE']) ? $_SERVER['MAGE_RUN_CODE'] : '';
  if ('' == $mageRunCode) 
   $mageRunCode = isset($_SERVER['REDIRECT_MAGE_RUN_CODE']) ? $_SERVER['REDIRECT_MAGE_RUN_CODE'] : $mageRunCode;
  
  
  /* Run store or run website */
  $mageRunType = isset($_SERVER['MAGE_RUN_TYPE']) ? $_SERVER['MAGE_RUN_TYPE'] : 'store';
  if ('store' == $mageRunType) 
   $mageRunType = isset($_SERVER['REDIRECT_MAGE_RUN_TYPE']) ? $_SERVER['REDIRECT_MAGE_RUN_TYPE'] : $mageRunType;
  
  

  
  

What I get

This config is not enough (or is wrong) to make it work :

• In index.php, when I dump $mageRunCode just before the Mage::run() line, I get the correct value


• All homepages work (http://my.domain.local/aliasX/)


• When I set RewriteBase to /alias1/, all /alias1 based urls are working but not the others


• All other aliases' urls are redirected to alias1 homepage (and the dump shows the alias1 run code). This is normal, as I set RewriteBase to /alias1/
  

What I already tried and isn't described above

• I tried tu use <Location> in my vhost config to set conditional RewriteBase. But with Locations set, my urls are not correctly redirected to index.php and I get the good ol' white apache 404 page (with apache error logs like this one : File does not exist: /var/www/html/dev-site/code/catalog, referer: http://my.domain.local/alias1/)

What I dont want

vhost aliases pointing to subdirectories + duplicated .htaccess and index.php in these subdirectories

Any help, clue, link - you name it - will be highly appreciated (I'm not a sysadmin and currently wasting my client's money not being able to solve this issue)

You can try this:

NameVirtualHost *:80
DocumentRoot "/var/www/html/dev-site/code"
ServerName my.domain.local
RewriteEngine On
SetEnvIf Request_URI ^/alias1.* MAGE_RUN_CODE=pf_view
SetEnvIf Request_URI ^/alias1.* MAGE_RUN_TYPE=store
SetEnvIf Request_URI ^/alias2.* MAGE_RUN_CODE=es_view
SetEnvIf Request_URI ^/alias2.* MAGE_RUN_TYPE=store
SetEnvIf Request_URI ^/alias3.* MAGE_RUN_CODE=ta_view
SetEnvIf Request_URI ^/alias3.* MAGE_RUN_TYPE=store
<Directory /var/www/html/dev-site/code>
Order allow,deny
Allow from all
AllowOverride All
RewriteEngine On
Options +FollowSymlinks
</Directory>