Add option to defer apt installs

[rkawala]

The apps plugin will add packages during the customization phase. That adds time: my customization phase now goes on for several minutes. My goal: speed up the customization phase. One idea: an option to defer the apt install of some packages until after the SD card is burned, and encrypted, and boots for real, and successfully connects to the internet. If I never get that far, I haven't wasted any time on apt installs.

apt-cacher-ng helps. Customization would be even slower without it. But wouldn't it be great to divide all the apt updates into two groups: things you need the minute the SD card boots (e.g. btrfs-progs), which happen during customization, and things that can wait (e.g. git).

Using that as an example, I see a syntax something like --plugin apps:"name=my-stuff|apps=btrfs-progs|defer=git" which means "install btrfs-progs during customization, but don't install git until the burned SD card boots and connects to the internet."

[gitbls]

This is a GREAT idea, and highly aligned with my goals for sdm. The only issue that I see is if someone forgets about the delayed installs and reboots a wee bit too early, potentially interrupting an apt operation at an inopportune time. Hopefully I can coerce systemd to prevent that from happening. But if it does, it would be a one-time thing 😉

Thanks for the suggestion!

[rkawala]

Good point about what to do if the deferred installs haven't completed. Maybe you could open a shell window so the user could watch the apt installs run, which would make it easy to decide whether it was a good time for a reboot. If the user reboots too early, maybe that window would open again when they next booted the OS, and tried to resume from wherever it quit last time.

[gitbls]

What is this shell window of which you speak? There isn't one of those on my no-Desktop systems.

[gitbls]

Installing deferred apps will be done by a service that will run at boot. However, it won't run if any of these (not yet named/not yet located files) exists:

• startup: A normal startup is in progress. This will be set by the apps plugin if defer specified, and cleared at the end of sdm FirstBoot
• rootfs-encryption: A rootfs encryption is in progress. This will be set by the cryptroot plugin, and cleared by the encryption cleanup script
• user-blocked: A file that the user can create to block deferred app installation

[gitbls]

Also, I think the service can cause shutdown to be delayed until it completes. Need to hit the systemd docs for this 😐