Make guest username, uid, home directory configurable

[jandubois]

Also disallows the "admin" username by default (because it is a builtin user in Ubuntu), but can be overridden by setting it explicitly in lima.yaml.

user:
  name: john
  comment: John Doe
  uid: 1000
  home: "/home/{{.User}}"

Another change is that {{.User}} and {{.UID}} in host templates now expand to the host values and not the guest values. Note that on Windows the host user is something like runner\runneradmin and host uid something like S-1-5-21-2897396845-3571823323-1290545657-500 (on GitHub runner).

Setting home and comment does not work yet with alpine-iso because lima-init hardcodes the home directory to /home/$USER.linux and doesn't set the comment at all (implemented in lima-vm/alpine-lima#134).

Fixes #2117
Fixes #2037
Implements #2622

Replaces #2378

[jandubois]

I recommend using "Hide whitespace" for reviewing this PR, especially for osutil/user.go.

[afbjorklund]

• The code also implements support for setting user.gid but doesn't document it because cloud-init has no way to set it. We'll have to implement this ourselves in our ci scripts (if we want it).

In terms of features, it probably would be more useful to have "groups" (extra groups) than "gid" (not used so much)

[jandubois]

Should there be an option to avoid "mirroring" the host values, and go with the default ones from the cloud.cfg?

I don't know how we would set up ssh without knowing the username. If we can figure this out, then I think we should support this.

[jandubois]

In terms of features, it probably would be more useful to have "groups" (extra groups) than "gid" (not used so much)

I have removed all code related to gid, so we can figure out the correct schema in due time.

[AkihiroSuda]

The go name and the yaml name are inconsistent.

[jandubois]

I'm wondering if {{.Comment}} should be supported in host/guest templates. It would be easy to add, but I can't think of an actual use-case.

[jandubois]

I believe I've addressed all feedback now, PTAL

There are 2 open issues that should probably be done "later":

• Optionally don't add an additional user at all (but how do we set up ssh keys?)
• Add {{.Comment}} to host and guest templates (but why?)

[AkihiroSuda]

Thanks

[afbjorklund]

I'm wondering if {{.Comment}} should be supported in host/guest templates. It would be easy to add, but I can't think of an actual use-case.

I don't actually know the use case for GECOS (even finger has been removed, for "pinky") - it was just that all the cloud-config examples had gecos...

$ lima pinky $USER
Login    Name                 TTY      Idle   When             Where
anders   Anders               pts/0           2024-11-02 09:27 192.168.5.2

For the templates though, no idea.