Mac OS X Thin Imaging Pt.1

OK, so I understand I’m pretty late to the party when it comes to thin imaging. I guess I have just been stuck in my ways with monolithic style imaging processes (the process of creating an image with all software on and then deploying that image).

So recently I decided to rethink the way we do our Mac deployments. As I mentioned, we still deploy our Mac labs in a monolithic style. The problem with this is that the image is:

a) very large in size (currently 30+ GB)
b) short sighted in terms of software updates (e.g. the dreaded Flash Player update etc.)

So I began to research ways in which IĀ could redesign our system with a more streamlined approach. And I came across the term “thin imaging”. For those reading this that don’t know what this is, it is basically a way of deploying a “base image” of OS X. Preferably the image is of the latest OS X build and has never been booted. You may ask why… my reasons are because it makes for:

a) a smaller image to deploy
b) a more modular approach to future updates (e.g. when a Flash Player update is out, I can simply and easily remove the old version and install the new one across a whole lab from a management server).

In turn, this process would likely mean only re-imaging once a year, just to freshen the systems up.

So my investigations began with how I would do this. This led me back to a piece of software we have looked at in the past, AutoDMG.

AutoDMG allows you to create a base system image of a never before booted OS. Perfect. Let’s take another look at how we do this.

Open AutoDMG and you are presented with this:

Screen Shot 2015-10-30 at 15.15.44

Simply all you have to do is drop your OS X installer on to the target image (it’s worth noting that this doesn’t have to be the OS X Installer from the Mac App Store, it could be a previously created .dmg file).

After examining the installer, it will also search for the latest available Apple updates (pretty cool huh!). You can simply check apply, and click download to get the packages from the Apple servers.

Screen Shot 2015-10-30 at 15.18.51

So at this point you have an OS X Installer, and the downloaded software updates from Apple for the relevant OS you are building. At this point you could just go ahead and build your image – no harm in that. But you could also choose to add additional software! These can be .pkg files, also .dmg files and even cooler, they can even be .app files!

Screen Shot 2015-10-30 at 15.21.28

As I am taking the more modular approach, I am going to leave out the applications and take a look at how I can deploy apps to client computers at a later date. But something that is handy to add is a preconfigured user! Guess what, they’ve got that covered too!

So for this you need to download CreateUserPkg.

For this you simply need to set the username, password and set a profile picture (if you choose). Very handy for setting a local admin account by default!

Screen Shot 2015-10-30 at 15.25.18

Save the package and then simply drop that in the additional software section of AutoDMG. Done!

In Part 2 we will take a look at Munki and MunkiAdmin, before we learn how to import and distribute packages.

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  • Jay

    Good post, thanks. I see in your screenshot you use Munki, will you be writing about that in the future as well?

    • Simon

      Hi Jay, Yes, I will be writing about Munki, MunkiAdmin and AutoPkgr in future posts (still currently experimenting).

      • Jay

        Awesome, I’ll look forward to it!

  • David

    Love reading your articels

    • Simon

      Thanks David!