I wanted to write a mod_perl handler that would read vhost configurations out of a database. However, it made more sense, at least to get something working quickly, do to this as a <Perl> section in the configuration file

I guess this could be done as a mod_perl handler instead, and I hope to eventually do it that way (mostly as an exercise, actually) but here it is the way I have it working:

#
#
# create table vhosts
#   (ID  int(11) not null auto_increment,
#    servername  varchar(255),
#    serveralias  varchar(255),
#    docroot      varchar(255),
#    scriptalias  varchar(255),
#    primary key (ID)
#   )
#
#  Note: serveralias can be a space-separated list. Change the field to
#  a text field if you have more than 255 characters of aliases.
#        scriptalas should have a trailing slash
#

<Perl>

use DBI;

my $db       = 'DBI:mysql:vhosts';
my $login    = 'www';
my $password = 'www';

my $dbh = DBI->connect( $db, $login, $password );
my $sth = $dbh->prepare( "SELECT servername, serveralias,
                                 docroot, scriptalias
                            FROM vhosts " );
$sth->execute;
$sth->bind_columns( my ( $servername, $serveralias, 
                          $docroot, $scriptalias ) );
while ( $sth->fetch ) {
    push @{$VirtualHost{'*'}},  {
        ServerName   => $servername,
        ServerAlias  => $serveralias,
        DocumentRoot => $docroot,
        ScriptAlias  => "/cgi-bin/ $scriptalias",
    };
}
$sth->finish;
$dbh->disconnect;

</Perl>

This goes in httpd.conf, and requires mod_perl. And, of course, you can add additional fields if you need them, like ErrorLog and CustomLog.