Mac admin'ing

If Jamf recon is launching a du process that causes a CPU spike

If Jamf inventory (jamf recon) causes an extended CPU spike specifically related to the du command, you can fix that by going, in the Jamf settings, to Computer Management > Computer Management – Management Framework > Inventory Collection, and then uncheck the Include home directory sizes checkbox.

That is a system-wide setting, but especially if most or all of your fleet is one-to-one Macs (not shared Macs), it’s a good idea to do. Your jamf recon inventory runs will still report back free disk space, just not broken down by individual home directories.

Special shoutout to tlark and neilmartin83 on the MacAdmins Slack for giving me more context around this.

Mac admin'ing

Script to make Jamf Self Service policy install a Munki optional install

There is a huge project called jamJAR that seeks to integrate Munki and Jamf in a seamless way.

I’ve written a script that does something a bit less ambitious, but it may still be helpful to your organization if you are “using” Jamf Self-Service, really want to be using Managed Software Center, and still want to keep Self-Service around (either temporarily or semi-permanently).

Basically is a script that you can include in a Jamf Self-Service policy that will attempt to install a Munki optional install item. Just make the item name (not necessarily the same as the display name, mind you) the Parameter 4 in Parameter Values. Oh, and make sure that item actually is an optional install available in Managed Software Center!

The script will attempt to add that item to the SelfServeManifest. If the item already exists in the SelfServeManifest, the script will launch up Managed Software Center and try to focus on the item to basically say “Hey, remember this is already installed?” If the item doesn’t already exist in the SelfServeManifest, the script will add the item to the SelfServeManifest, launch up Managed Software Center, and attempt a managedsoftwareupdate --auto run.

As it’s written, it’s using Munki’s embedded Python 3, but if you have your own Python 3 you’d rather use, just update the shebang path.

Mac admin'ing

Fixing Jamf device signature error

Even though this Jamf Nation thread is five years old, as of this writing, it’s still got the solution to the Device Signature Error - A valid device signature is required to perform the action error message.

In my experience, the actual working solution is to run sudo jamf enroll -prompt and then enter credentials when prompted. Repeatedly running sudo jamf recon (even after a reboot) or sudo jamf policy doesn’t fix the issue, nor does verifying that the system clock time is correct.

Now why this comes up in the first place on a freshly factory-reset computer that DEP-enrolled in Jamf—who knows but Jamf?