Install or Defer

This framework will enforce the installation of pending Apple security updates on Jamf Pro-managed Macs. Users will have the option to Install or Defer. After a specified amount of time passes, the Mac will be prompted to install the updates, then restart automatically if any updates require it.

This workflow is most useful for updates that require a restart and include important security-related patches (e.g. macOS Ventura 13.1), but also applies to application updates that don't require a restart (e.g. Safari 16.2). Basically, anything Software Update marks as "recommended" or requiring a restart is in scope.

This framework is distributed in the form of a munkipkg project, which allows easy creation of a new installer package when changes are made to the script or to the LaunchDaemon that runs it. See the Installer creation section below for specific steps on creating the installer for this framework.

Requirements

Here's what needs to be in place in order to use this framework:

• The current version of this framework officially supports macOS Big Sur, Monterey, Ventura, and Sonoma, but older script versions should continue to function normally for previous macOS releases (note, however, that those versions of macOS are no longer receiving regular security updates from Apple and thus may not benefit from this framework).
• Target Macs must be enrolled in Jamf Pro and have the jamfHelper binary installed.

Optional

You might also consider implementing a Mac with Content Caching service active at all major office locations. This will conserve network bandwidth and improve the download speed of updates.

Assumptions

The following is assumed to be the case when implementing this framework:

• An automatic restart is desired when updates require it. This script is not necessary if restart-required updates are not mandatory within your environment and are instead left up to the person managing the Mac.
• The Jamf Pro server has one or more policies that regularly collect inventory updates from the Mac fleet. This will ensure that Install or Defer is only pushed to a Mac that has a pending update and avoids false-positive script runs (even though the script will not display any alerts if no updates are needed, pushing it to a Mac with no pending updates results in unnecessary memory and network bandwidth usage and should be avoided).

Workflow detail

Here's how everything works, once it's configured:

1. When a new desired Apple security update is released, the Jamf Pro administrator creates a smart group for Macs that need this update, and adds it to the existing policy scope.
2. Macs that meet the smart group criteria run the policy at next check-in.
3. The policy installs a package that places a LaunchDaemon and a script.

4. The LaunchDaemon executes the script, which performs the following actions:

   1. The script runs softwareupdate --list to determine if any updates are required (determined by whether the update is labeled as recommended and/or requiring a restart). If no such updates are found, the script and LaunchDaemon self-destruct.

   2. If a required update is found, an onscreen message appears, listing the new updates that are required to be installed. Two options are given: Install or Defer.

      (Note: your company logo will appear in place of the Software Update icon, if you specify the LOGO path.)

      

   3. If the user clicks Defer, the prompt will be dismissed. The next prompt will reappear after 4 hours by default (this is customizable). Users can continue to defer the prompt each time it appears for up to 72 hours (also customizable).
   4. When the user clicks Install, the script runs software updates.
5. If the deferral deadline passes, the script behaves differently:
   1. The user sees a non-dismissible prompt asking them to run updates immediately.
   2. If the user ignores the update prompt for 10 minutes, the script applies software updates in the background.
6. After the updates are done installing, if a restart is required:
   1. A "soft" restart is attempted.
   2. 5 minutes after the "soft" restart attempt, if the user still has not restarted (or if unsaved work prevents the "soft" restart from occurring), the script forces a restart to occur.

Limitations

The framework has a few limitations of note:

• If multiple sequential security updates are available, they may be treated as two separate rounds of prompting/deferring. As a result, Macs requiring sequential updates may take more than one deferral and enforcement cycle (default 3 days) to be fully patched.
• Reasonable attempts have been made to make this workflow enforceable, but there's nothing stopping an administrator of a Mac from unloading the LaunchDaemon or resetting the preference file.
• On Apple Silicon Macs, running softwareupdate --download and softwareupdate --install via background script are unsupported. When this framework is run on an Apple Silicon Mac, enforcement instead takes a "softer" form, opening Software Update and leaving a persistent prompt in place until the updates are applied. Note that this workflow requires the Software Update preference pane to be available to a user with a secure token and volume ownership, so that they can apply available software updates and restart their Mac.
• macOS will occasionally present major macOS upgrades (such as macOS Sonoma) on Macs running previous releases, even if an MDM profile deferring major updates is in place. The suggested workaround is to also defer minor updates (possibly for a shorter period) until you can approve the major upgrade in your environment. This script will remove Sonoma as a listed update when on macOS Ventura or older, but if the Mac sees multiple updates requiring restart, the deferred update may still be installed.
• macOS Big Sur, macOS Monterey, and macOS Ventura (prior to version 13.3) had known reliability issues when attempting to update your Mac using the softwareupdate binary, resulting in inconsistently presenting new updates as available or failing to install updates. Some measures have been taken to improve the reliability of this script when encountering these issues, but the recommendation for a fix is to upgrade to the current supported macOS release, as Apple is no longer providing bug fixes for these macOS versions beyond security patches.

Settings customization

This framework is designed to work "out of the box" without any modification, but if you wish to customize the workflow to your organization's needs (e.g. changing wording in the alerts, adding corporate branding, adjusting alert timing and the maximum deferral time before update enforcement), you can make whatever changes are needed, either by deploying a configuration profile, or by directly modifying the script (payload/Library/Scripts/Install or Defer.sh) with a text editor (e.g. Atom) and building an installer package for deployment of your customized script.

Configuration profile

You can customize many settings using a configuration profile targeting the $BUNDLE_ID preference domain. This allows you to apply different configurations to different groups of Macs (e.g. a dedicated test group could have shorter deferral times), and lets you make changes to these settings on the fly without repackaging and redeploying the script. The following settings can be defined via configuration profile keys:

Keys

Alerting

Timing

Backend

Create a configuration profile in Jamf Pro

1. Open the Install or Defer profile manifest in ProfileManifestsMirror.
2. Copy the raw contents of the file to your clipboard.
3. Create the configuration profile:
   1. In the Jamf Pro web app, create a new configuration profile.
   2. Under the General payload, give the configuration profile a unique name, assign a category, and set Level to Computer Level.
   3. Under Scope, specify the groups that will receive this profile for enforced settings. You can assign it to all computers, limit it to individual test computers, or specify one or more computer groups.
   4. Select the Application & Custom Settings payload, then click External Applications.
   5. Click ➕ Add and select Custom Schema from the Source menu.
   6. Enter the bundle identifier (com.github.mpanighetti.install-or-defer) under Preference Domain.
   7. Under Custom Schema, click ➕ Add schema.
   8. Paste the raw contents from the Install or Defer profile manifest into the text editor window, then click Save.
   9. Make all desired selections, using the descriptions on the page or the above table for reference. None of these are required settings; leaving one undefined will revert to script default settings for that feature.
   10. Once the profile is finished, click Save.

Script variables

There are several settings in the script that can be customized by changing default variable values:

File paths and identifiers

• PLIST

  Path to a plist file that is used to store settings locally. Omit ".plist" extension.

• BUNDLE_ID

  The identifier of the LaunchDaemon that is used to call the Install or Defer.sh script, which should match the file name in the payload/Library/LaunchDaemons folder. Omit ".plist" extension.

• SCRIPT_PATH

  The file path of the Install or Defer.sh script. Used in the script to assist with resource file clean-up.

Messaging

• MSG_INSTALL_OR_DEFER_HEADING

  The heading/title of the message users will receive when updates are available.

• MSG_INSTALL_OR_DEFER

  The body of the message users will receive when updates are available.

• MSG_INSTALL_HEADING

  The heading/title of the message users will receive when they must run updates immediately.

• MSG_INSTALL

  The body of the message users will receive when they must run updates immediately.

• MSG_INSTALL_NOW_HEADING

  The heading/title of the message users will receive when a manual update action is required.

• MSG_INSTALL_NOW

  The body of the message users will receive when a manual update action is required.

• MSG_UPDATING_HEADING

  The heading/title of the message users will receive when updates are running in the background.

• MSG_UPDATING

  The body of the message users will receive when updates are running in the background.

The above messages use the following dynamic substitutions:

• %DEADLINE_DATE% will be automatically replaced with the deadline date and time before updates are enforced.
• %DEFER_HOURS% will be automatically replaced by the number of days, hours, or minutes remaining in the deferral period.
• %SUPPORT_CONTACT% will be automatically replaced with "IT" or a custom value set via configuration profile key.
• %UPDATE_LIST% will be automatically replaced with a comma-separated list of all recommended updates found in a Software Update check.
• The section in the {{double curly brackets}} will be removed when this message is displayed for the final time before the deferral deadline.
• The sections in the <<double comparison operators>> will be removed if a restart is not required for the pending updates.

Installer creation

1. Install the packaging prerequisites:

   • Python (does not ship with latest macOS; easiest way to get it is by installing Xcode Command Line Tools: xcode-select --install)
   • munkipkg

2. Make all desired modifications to the framework. If you make changes to the script, we recommend changing the following three things:

   • The Last Modified metadata in the script.
   • The Version metadata in the script.
   • The version key in the build-info.plist file (to match the script version).

3. With munkipkg installed and with python in your $PATH definitions, this command will generate a new installer package in the build folder (replace paths with the full path to munkipkg and install-or-defer respectively):

   python /path/to/munkipkg /path/to/install-or-defer

4. The subsequent installer package can be uploaded to Jamf Pro and scoped as specified below in the Jamf Pro setup section.

See the munkipkg README for more information on how to use the tool.

Jamf Pro setup

The following objects should be created on the Jamf Pro server in order to implement this framework:

Packages

Upload this package (created with munkipkg above) to the Jamf Pro server via Jamf Admin or via the Jamf Pro web app:

• install-or-defer-x.x.x.pkg

Smart Groups

Create a smart group for each software update or operating system patch you wish to enforce. Here are some examples to serve as guides, using regular expressions to allow for fewer criteria:

macOS update regex

• Critical Update Needed: macOS Ventura 13.1
  • Operating System Build matches regex ^22[A-B]

Application update regex

• Critical Update Needed: Safari 16.2
  • Application Title is Safari.app
  • and ( Application Version matches regex ^(\d|1[0-5])\.
  • or Application Version matches regex ^16\.[0-1]$ )

Policy

Create a policy with the following criteria:

• Name: Install or Defer
  • Triggers:
    • Recurring check-in
    • Custom: install-or-defer
  • Execution Frequency: Once every week¹
  • Packages:
    • install-or-defer-x.x.x.pkg
  • Scope:
    • One or more test Macs with one or more pending security updates.

Testing

1. On a test Mac in scope for the Install or Defer policy, open Console.app and filter for the Process logger, or run this Terminal command:

   log stream --style syslog --predicate 'senderImagePath ENDSWITH "logger"'

2. Open Terminal and trigger the "stash" policy that deploys the logo graphics, if not already installed:

   sudo jamf policy -event stash

3. Then trigger the Install or Defer policy:

   sudo jamf policy -event install-or-defer

4. Enter your administrative password when prompted.

5. The policy should run and install the script/LaunchDaemon. Switch back to Console to view the output. You should see something like the following:

   default 16:21:07.693371 -0700   logger  Starting Install or Defer.sh script. Performing validation and error checking...
   default 16:21:09.153793 -0700   logger  Validation and error checking passed. Starting main process...
   default 16:21:09.153839 -0700   logger  No logo provided, or no logo exists at specified path. Using Software Update icon.
   default 16:21:09.884776 -0700   logger  Maximum deferral time: 72h:00m:00s
   default 16:21:10.024080 -0700   logger  Deferral deadline: 2020-04-05 16:21:09
   default 16:21:10.026087 -0700   logger  Time remaining: 71h:59m:59s
   default 16:21:10.044935 -0700   logger  Checking for pending system updates...
   default 16:21:39.218631 -0700   logger  Software Update Tool
   default 16:21:39.218681 -0700   logger
   default 16:21:39.218704 -0700   logger  Finding available software
   default 16:21:39.218724 -0700   logger
   default 16:21:39.326278 -0700   logger  Downloaded Safari
   default 16:24:26.066989 -0700   logger  Downloading Security Update 2020-002
   default 16:24:26.067232 -0700   logger  Downloaded Security Update 2020-002
   default 16:24:26.067356 -0700   logger  Done.
   default 16:24:26.122639 -0700   logger  Prompting to install updates now or defer...

6. After the updates are downloaded, you should see the following prompt appear onscreen:

7. Click Defer. You should see something like the following output appear in Console:

   default 16:24:34.444397 -0700   logger  User clicked Defer after 00h:00m:08s.

8. Run the following command in Terminal:

   sudo defaults read /Library/Preferences/com.github.mpanighetti.install-or-defer

   You should see something similar to the following output (the numbers, which represent dates, will vary):

       UpdatesDeferredUntil = 1585884274;
       UpdatesForcedAfter = 1586042469;

9. Enter the following commands to "skip ahead" to the next deferral and re-trigger the prompt:

   sudo defaults write /Library/Preferences/com.github.mpanighetti.install-or-defer UpdatesDeferredUntil -int $(date +%s)
   sudo launchctl unload /Library/LaunchDaemons/com.github.mpanighetti.install-or-defer.plist
   sudo launchctl load /Library/LaunchDaemons/com.github.mpanighetti.install-or-defer.plist

10. You should see the install/defer prompt appear again.

11. Click Install. As long as there are no apps with unsaved changes, the Mac will run updates in the background. You should see the following prompt appear onscreen:

    • If you want to test the "hard" restart feature of this framework, open Terminal and type top before the updates finish running. Then wait 5 minutes after "soft" restart attempt, and confirm that the Mac restarts successfully.

12. After updates are installed and (optionally) the Mac is successfully restarted, you should not see any more onscreen messages.

13. (OPTIONAL) If an additional round of updates is needed, run sudo jamf policy -event install-or-defer again to start the process over. Sequential updates cannot be installed as a group (see Limitations section above).

Deployment

Once the Testing steps above have been followed, there are only a few steps remaining to deploy the framework:

1. In the Jamf Pro web app, edit the Install or Defer policy and click on the Scope tab.
2. Remove the test Macs from the scope.
3. Add all the Critical Update Needed smart groups into the scope.
4. Click Save.
5. Monitor the policy logs to ensure the script is working as expected.

Rollback

If major problems are detected with the update prompt or installation workflow, disable the Install or Defer policy. This will prevent computers from being newly prompted for installation of updates.

Note that any computers which have already received the framework push will continue through the motions of alerting, deferring, updating, and restarting. If you need to remove the framework from your fleet and stop it from running, you could write an uninstall script using the preinstall script as a foundation (it would basically just need to unload the LaunchDaemons and remove the resource files).

Once the script is debugged and updated, you can generate a new installer package, upload the package to the Jamf Pro server, link it to the policy, and re-enable the policy. The preinstall script will remove any existing resources and replace them with your modified files.

Troubleshooting

Error "Path had bad ownership/permissions" when running LaunchDaemon

This most likely means that Install or Defer was manually downloaded and modified, and the LaunchDaemon was given incorrect ownership and permissions in the process of downloading the resource files. If you're using munkipkg to build the package, this should be fixed as of version 3.0.1, but if you're packaging the project using other means, make sure you run these commands beforehand:

sudo chown root:wheel /path/to/install-or-defer/payload/Library/LaunchDaemons/com.github.mpanighetti.install-or-defer.plist
sudo chmod 644 /path/to/install-or-defer/payload/Library/LaunchDaemons/com.github.mpanighetti.install-or-defer.plist

Miscellaneous Notes

• Feel free to change the com.github.mpanighetti bundle identifier to match your company instead. If you do this, make sure to update the filenames of the LaunchDaemons, their corresponding file paths in the preinstall and postinstall scripts, the $BUNDLE_ID variable in the script, and the bundle identifier used for settings enforced via configuration profile.
• If you encounter any issues or have questions, please open an issue on this GitHub repo.

Enjoy!

¹ This example frequency assumes you're using the default deferral period of 72 hours. If you've set a custom deferral period, it is recommended that your policy runs less frequently than the maximum deferral time, so that your Macs have the chance to defer, timeout, and apply the updates before the policy attempts to run again (since the preinstall script will reset UpdatesDeferredUntil and UpdatesForcedAfter).