feat(config): make it so you can revert override of apps

[StealthyCoder]

This is to add a way to disable the override, inherit from parent concerning apps running on devices.

Relevant fioconfig code

[vkhoroz]

Looking at sota.Delete IIUC there are two use cases when it can return an error:

1. A key is malformed.
2. A key is not found.

Here, (1) is a programming error deserving DieNotNil, while (2) would be better off silently ignored.
Thus, I suggest to improve this code using sota.Has.

Suggested change

	err = sota.Delete("pacman.docker_apps")
	if err != nil {
	fmt.Printf("Error trying to delete pacman.docker_apps key: %s\n", err)
	}
	sota.Delete("pacman.compose_apps")
	if err != nil {
	fmt.Printf("Error trying to delete pacman.compose_apps key: %s\n", err)
	}
	if sota.Has("pacman.docker_apps") {
	subcommands.DieNotNil(sota.Delete("pacman.docker_apps"))
	}
	if sota.Has("pacman.compose_apps") {
	subcommands.DieNotNil(sota.Delete("pacman.compose_apps"))
	}

[vkhoroz]

The other option, as we know a key we pass is properly formatted, would be to make an "optimistic" assumption that sota.Delete always succeeds from a practical perspective:

Suggested change

	err = sota.Delete("pacman.docker_apps")
	if err != nil {
	fmt.Printf("Error trying to delete pacman.docker_apps key: %s\n", err)
	}
	sota.Delete("pacman.compose_apps")
	if err != nil {
	fmt.Printf("Error trying to delete pacman.compose_apps key: %s\n", err)
	}
	_ = sota.Delete("packman.docker_apps")
	_ = sota.Delete("packman.compose_apps")

[StealthyCoder]

Even though we have properly formatted ones, maybe in the future some other error check will be introduced so I went with the aforementioned one. Check of the key and delete it.

[doanac]

explain that none means "run no apps"

[doanac]

explain what "parent" means.

[doanac]

explain what "parent" and "none" mean here also

[vkhoroz]

I would state explicitly here that we are inheriting from the group config.

Suggested change

	fioctl devices config updates <device> --apps -`,
	# Set the docker apps to inherit from a group config:

We might be more verbose (like below), but I think that is apparent from the fioctl config updates help.

Suggested change

	fioctl devices config updates <device> --apps -`,
	# Set the docker apps to inherit from a group config (if set there) or a system default (otherwise):

[vkhoroz]

Once I wrote this I understood we don't yet have a way to restore the device tag to inherit from a group config or system default.
Do we need one?

@doanac @mike-scott ^^^

[doanac]

probably should do it also

[mike-sul]

Tangential note: we don't need to support pacman.docker_apps not sure we've ever used it.
We deprecated it in v75 in this commit foundriesio/aktualizr-lite@34f8f70

[doanac]

We still aren't explain what the "parent" will be. I'm not sure parent is a good word. What we are trying to describe is how are config files are processed. We use the same logic as systemd where we walk through:

• /usr/lib/sota/conf.d/
• /var/sota/sota.toml
• /etc/sota/conf.d/

We need a concise way to explain this.

And that , and - are so subtle here that we should probably call out that they are special characters.

[vkhoroz]

IIUC the group level is the top one here (as we allow no factory-wide updates config).
So, probably, we may put here a sentence like this:

Suggested change

	# If for a device apps are set - those apps are installed
	# Set the docker apps to a system default (all apps on most devices):

A system default seems to be rather specific to me, without diving into internal details (which can differ from device to device).