Just the other day macOS Mojave was released and now the armies of Macs armed only with the AppStore are silently downloading the installer and ready to upgrade. You can’t hurry too fast to be on the bleeding edge, hurry faster!

Just in case you don’t want everyone to install macOS 10.14.0 (dot zero!) in the first week of its release here’s a way to slow down the upgrade hordes using Erik Berglund’s AppBlocker script. Erik Berglund is also the author of ProfileCreator (for creating profiles) and the author of many other great scripts.

Note: for true binary whitelisting check out Google’s Santa project and Upvote (and Moroz and Zentral, two other Santa sync servers).

Step 1. Get it

Clone or download the AppBlocker project from GitHub

Step 2. Do it

Edit the AppBlocker.py script with the Bundle Identifier of your app to block, in this case for the Mojave installer from the AppStore it is:

com.apple.InstallAssistant.Mojave

You can also edit the alert message, and the icon that is shown, as well as decide if the blocked app should be deleted or not. The script is easy to edit in BBEdit, or nano (in Terminal). Use whatever your favorite text editor is to make the necessary changes.

# List of all blocked bundle identifiers. Can use regexes.
blockedBundleIdentifiers = ['com.apple.InstallAssistant.Mojave']

# Whether the blocked application should be deleted if launched
deleteBlockedApplication = False

# Whether the user should be alerted that the launched applicaion was blocked
alertUser = True

# Message displayed to the user when application is blocked
alertMessage = "The application \"{appname}\" has been blocked by IT"
alertInformativeText = "Contact your administrator for more information"

# Use a custom Icon for the alert. If none is defined here, the Python rocketship will be shown.
alertIconPath = "/System/Library/CoreServices/CoreTypes.bundle/Contents/Resources/Actions.icns"

UPDATED NOTE:

To determine the Bundle identifier of other applications you can use osascript

osascript -e 'id of app "iTunes"'

com.apple.iTunes

If you want to block more than one app use a comma separated list in the AppBlocker.py script:

['com.apple.InstallAssistant.Mojave','com.apple.iTunes']

 

Step 3. Run it

Put the script where you want to run it. The default location as defined in the launchd plist included with the app is “/usr/local/bin”. Put the launchd.plist in “/Library/LaunchDaemons/” and start up your launchd to block your apps!

launchctl load /Library/LaunchDaemons/com.github.erikberglund.AppBlocker.plist

Step 4. Automate it

For bonus points we automate! Bundle it all up in a package with munkipkg, then distribute it with Munki to all your clients.

Using munkipkg is easy. Create the folder using munkipkg

./munkipkg --create AppBlocker

munkipkg: Created new package project at AppBlocker

Then you fill the payload folders with those items you downloaded from the AppBlocker project. LauchD plist in the LaunchDaemons folder and AppBlocker.py in the “usr local bin” (create each nested folder).

And finally create a post install script (no “.sh”) with the launchctl action to start your plist.

Last but not least add this package to your Munki repo as an unattended managed install  that everyone gets. Of course, only do this after testing your package locally somewhere to verify that it works properly. Remember the saying: “You may not test very often, but when you do it’s always in production.” Be very careful with your testing but always automate all the things.

Updated after the initial blog post to explain how to add more than one app to block, and how to use osascript to determine the bundle identifier.