Configuring a catch-all VirtualHost for Apache2

Recently I noticed an interesting behavior of my Apache2 setup when I introduced a new VirtualHost and enabled the site. Usually I store the configuration for each host in an individual file, because it is much easier to maintain. The main page that I serve is this WordPress blog, having the ServerName blog.stefanproell.at and several aliases. The configuration files have the same name as the ServerName of the VirtualHost they configure. When a request comes in, Apache2 passes it to the first VirtualHost having a server name or alias fitting to the request. If no atch can be found, the request is handled by the first VirtualHost that can be found. This is obviously the one having the config file with the alphabetically first file name. Without noticing, the first config file to be read was exactly this blog. Other services and hosts have their configuration files names starting with letter being later in the alphabet than the blog, hence they were read later. So every unknown request was handed over to the blog, which is nice as I want to have it like this anyway.

But when I introduced a new host having a filename say 123.stefanproell.at for its config file, each request not to be answered by any host was handled by the new host 123.stefanproell.at. So far, this is no surprise at all, but then it got weird. As suggested by a lot of different sources and the official documentation, I declared a default page, having a filename with an alphabetically even lower letter: 000-default.

Also the directive especially designed for this porpose of having a wildcard VirtualHost did not work as expected. This directive

<VirtualHost _default_:*>
DocumentRoot /www/default
</VirtualHost> 

should according to the documentation

prevent any request going to the main server. A default vhost never serves a request that was sent to an address/port that is used for name-based vhosts. If the request contained an unknown or no Host: header it is always served from the primary name-based vhost (the vhost for that address/port appearing first in the configuration file).

But instead of serving an empty default page for every missed request, Apache2 stated to serve every request to the default page, although the other VirtualHosts have been defined. The same behavioralso occurred when the specific

 _default_ 

directive was not applied.

What I ended up with was a solution where I explicitly defined a dummy,catch all host having the lowest file name for its configuration. So now I have a fully configured VirtualHost having the configuration file name 000-dummy.stefanproell.at and the content

ServerAdmin webmaster@localhost
ServerName dummy.stefanproell.at
DocumentRoot /var/www/default

Do not forget to provide a DNS entry pointing to dummy.stefanproell.at as well.

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