Using the macOS High Sierra OS installer’s startosinstall tool to install additional packages as post-upgrade tasks

Starting with macOS 10.12.4, Apple locked down the macOS installer to make it impossible to add non-Apple installer packages directly to the macOS Install .app without using NetInstall. However, there is a way to configure the macOS High Sierra OS installer to install additional packages as a post-upgrade task. For more details, please see below the jump.

Using the macOS High Sierra OS installer’s startosinstall tool to avoid APFS conversion

As part of the upgrade process to macOS High Sierra, Apple has stated that certain drives will be converted from using the HFS+ filesystem to Apple’s new default filesystem, APFS. The conversion criteria is shown below:

For those Mac admins who don’t necessarily want to convert yet, there is a way to configure the macOS High Sierra OS installer to skip the APFS conversion. For more details, please see below the jump.

Changing local account passwords may cause new login keychain to be silently generated on macOS High Sierra

As part of my testing of macOS High Sierra, I’ve noticed that login behavior has changed for local accounts, in cases where the password of the login keychain is different from the password of the account logging in.

On macOS Sierra, the following behavior occurs when the password of the login keychain is different from the password of the local account logging in:

1. The login process pauses
2. You’re prompted to continue login, create a new keychain, or update the existing keychain password.

3. If you choose to update the existing keychain password, you enter the keychain’s current password (which is usually the account’s former password.)

4. The login process proceeds and the desktop comes up.

On macOS High Sierra, the following behavior occurs when the password of the login keychain is different from the password of the local account logging in:

1. The login keychain with the different password is renamed to login_renamed_number_goes_here.keychain-db and stored in ~/Library/Keychains.

2. A new login keychain is created in ~/Library/Keychains. The new login keychain is named login.keychain-db and uses the password of the local account logging in.

Note: This is behavior I’ve observed for local accounts only. I have not been able to test with network accounts, like Active Directory mobile accounts.

Update 9-26-2017: This behavior was addressed in the betas for Active Directory mobile accounts:

For reference, this _was_ broken for AD mobile accounts until we reported it

Didn’t try it with local

— mikeymikey (@mikeymikey) September 26, 2017

The reason why this behavior is problematic is that anything stored in the former login keychain is not transferred to the new login keychain. Saved passwords, certificates, and any other secrets stored in the now-former login keychain will not be present in the new login keychain. They will need to be manually copied, or re-saved into the new login keychain.

For more details, see below the jump.

APFS preparation and macOS High Sierra

As part of the pre-release announcements about macOS High Sierra, Apple released the following KBase article:

• Prepare for APFS in macOS High Sierra: https://support.apple.com/HT208018

Apple makes a number of statements about APFS and its effects in this KBase article, but what do they all mean? I’m going to try to clarify while staying on the right side of Apple’s NDA. For more details, see below the jump.