Mount a dmg off a web server

I saw this project by Douglas Nerad which stream lines the bootstrapping installation of Munki, so that you can do it while booted from the Recovery partition. This is useful to inject munkitools on a new Mac without having to go through setting up a user.

The read me recommends to put the script and other resources on a USB key, which works fine, as long you have only one USB key. If you have to share this tool among multiple admins keeping the keys up to date (and in your pocket) can be a pain.

If you put all the resources and the script in an dmg file on a web server, you can run

hdiutil attach http://webserver/path/to/InstallThis.dmg

and then run scripts and installer pkgs from the attached volume.

installer -pkg /Volumes/InstallThis/munkitools2-latest.pkg
/Volumes/InstallThis/setupEverything.sh

Note that you cannot run python scripts from the Recovery partition. It is best to use shell or bash scripts.