Setting a 'server maintenance' page for all virtual hosts

[subBlue]

I'm needing to do some major upgrades to our server which will mean the Rails based sites will be down for an hour or two (need to upgrade Ruby and all the required gems). I'm wondering if there is a simple way I can put up a server maintenance page up for all the virtual hosts without having to go through each and set it by hand (there are about 40 virtual hosts)?

Thanks.

[subBlue]

Second thoughts, is there a way to customise the default 403 error page you get when disabling a virtual host? This would make it very easy to show a maintenance page when doing upgrades.

[mistwang]

The easiest way to make a server wide maintenance page probably is to change the default listener to another port, then create a temp listener mapping to a temp vhost with the maintenance page.