Performs a macOS Upgrade to Monterey in munki by using this is a postinstall_script. Requires changing the type of installer from *startosinstall* to *copy_from_dmg*. Since we use Jamf Pro we make use of the jamfhelper to block out the screen as the upgrade begins.

MontereyPostInstall.sh

#!/bin/sh
: '
------------------------
  Penn State MacAdmins
------------------------
Performs the following:
  - Installs the latest version of macOS by using the current copied
  version from munki
Sources:
  - https://scriptingosx.com/2019/09/get-current-user-in-shell-scripts-on-macos/
  - https://www.xmodulo.com/catch-handle-errors-bash.html
-----------------------------------------------
  Joshua D. Miller - [email protected]
  Last Updated - February 23, 2022
-----------------------------------------------
'

macOSVersion="Monterey"
### Get Current Architecture ###
ARCH=$(/usr/bin/arch)
### Set macOS Installer Path ###
STARTOSINSTALL_PATH="/Applications/Install macOS "$macOSVersion".app/Contents/Resources/startosinstall"
### Create jamf Dialog to block user access ###
## Set our Variables for the window ##
TITLE="macOS Upgrade"
ICON="/Applications/Install macOS "$macOSVersion".app/Contents/Resources/ProductPageIcon.icns"
HEADING="macOS Device Upgrade"
DESCRIPTION="Please be patient as we begin the upgrade process of your machine.
Once the machine reboots, the upgrade process can take up to an hour to complete."

### jamf Full Screen Dialog function ###
jamf_dialog () {
  /Library/Application\ Support/JAMF/bin/jamfHelper.app/Contents/MacOS/jamfHelper \
  -windowType fs -title "$TITLE" \
  -icon "$ICON" \
  -heading "$HEADING" \
  -description "$DESCRIPTION" &
}
### Verify Volume Ownership of Current User ###
verify_volume_owner () {
  ## Grab the Current Users allowed to unlock the disk and output to temporary PLIST ##
  DISKUTIL_PATH="/private/tmp/diskutil.plist"
  CRYPTO_PLIST=$(/usr/sbin/diskutil apfs listCryptoUsers / -plist > $DISKUTIL_PATH)
  ## Start Counter ##
  COUNTER=0
  declare -i CRYPTO_USER_COUNT=$(/usr/bin/xmllint --xpath 'count(//plist/dict/array/dict)' $DISKUTIL_PATH)
  while [[ $COUNTER -le $CRYPTO_USER_COUNT ]]
  do
      ## Get List Item UUID ##
      CRYPTO_USER_UUID=$(/usr/libexec/PlistBuddy -c "print :Users:$COUNTER:APFSCryptoUserUUID" $DISKUTIL_PATH)
      if [[ "$CRYPTO_USER_UUID" == "$CURRENT_USER_UUID" ]]
      then
        VOLUME_OWNER_STATUS=$(/usr/libexec/PlistBuddy -c "print :Users:$COUNTER:VolumeOwner" $DISKUTIL_PATH)
        if [[ $VOLUME_OWNER_STATUS == true ]]
        then
          /bin/echo "$CURRENT_USER is a Volume Owner"
          return true
        else
          /bin/echo "$CURRENT_USER is NOT a Volume Owner. Exiting"
          return false
        fi
      else
        COUNTER=$((COUNTER + 1))
        continue
      fi
  done

}

### Install macOS function ###
install_macOS () {
  ### Install macOS based on architecture ###
  if [ "$ARCH" == "arm64" ]
  then
    ### Get the current user logged in and password ###
    CURRENT_USER=$(/bin/echo "show State:/Users/ConsoleUser" |
                   /usr/sbin/scutil | /usr/bin/awk
                   '/Name :/&&!/loginwindow/{print $3}')
    ## Get User ID ##
    USER_ID=$(/usr/bin/id -u "$CURRENT_USER")
    ## Verify Disk Ownership ##
    USER_CAN_START_UPGRADE=verify_volume_owner
    if [[ $USER_CAN_START_UPGRADE == true ]]
    then
      ## Get Password ##
      PASSWORD="$(/bin/launchctl "asuser" "$USER_ID" sudo -u "$CURRENT_USER" /usr/bin/osascript -e '
        display dialog "Please enter your current macOS Password:"
        default answer ""
        with title "Upgrade macOS"
        with text buttons {"OK"}
        default button 1 with hidden answer' -e '
        return text returned of result')"
      PASSWORD=$(printf '%s\n' "$PASSWORD" | sed -e 's/[]\/$*.^[]/\\&/g')
      /bin/echo "$PASSWORD" | "$STARTOSINSTALL_PATH" --agreetolicense --forcequitapps --user "$CURRENT_USER" --stdinpass
    else
      /bin/echo "Unable to initiate upgrade of macOS as this device is an Apple Silicon device and user $CURRENT_USER does not have the ability to unlock the disk."
      return 1
    fi
  else
    "$STARTOSINSTALL_PATH" --agreetolicense --forcequitapps
  fi
}

jamf_dialog
if ! install_macOS
then
    /bin/echo "Unable to start the upgrade process. Exiting..."
    /usr/bin/killall jamfHelper
    exit 1
fi

exit 0