Re: [gentoo-dev] [PATCH] acct-user.eclass: don't modify existing user by default

[Mike Gilbert]

On Sun, Jan 3, 2021 at 8:35 PM Thomas Deutschmann <whissi@g.o> wrote:
>
> Modifying an existing user is a bad default and makes Gentoo
> special because it is common for system administrators to make
> modifications to user (i.e. putting an user into another service's
> group to allow that user to access service in question) and it
> would be unexpected to see these changes reverted during normal
> world upgrade (which could break services).
>
> This commit will make Gentoo behave like any other Linux distribution
> by respecting any user modifications by default. However, we will retain
> the functionality to reset system user and groups and users interested
> in this feature can opt-in by setting
> ACCT_USER_ALLOW_EXISTING_USER_TO_BE_MODIFIED to a non-zero value in
> their make.conf.

So the main problem I see with doing this is that it becomes
impossible to reliably make changes to a user in later ebuild
revisions. Developers may want/need to deploy changes to user
attributes. Changing group memberships seems like the best example,
but I could foresee a want/need to change DESCRIPTION, HOME, or SHELL
as well.

Because of this, I think the new behavior should be opt-in, and people
who use it should be aware that they will need to pay attention if any
account changes are rolled out in new ebuild versions.

> diff --git a/eclass/acct-user.eclass b/eclass/acct-user.eclass
> index 22b0038fbff7..d60b1e53b4bb 100644
> --- a/eclass/acct-user.eclass
> +++ b/eclass/acct-user.eclass
> @@ -309,6 +321,20 @@ acct-user_pkg_pretend() {
>         fi
>  }
>
> +# @FUNCTION: acct-user_pkg_setup
> +# @DESCRIPTION:
> +# Initialize internal environment variable(s).
> +acct-user_pkg_setup() {
> +       debug-print-function ${FUNCNAME} "${@}"
> +
> +       # check if user already exists
> +       ACCT_USER_ALREADY_EXISTS=
> +       if [[ -n $(egetent passwd "${ACCT_USER_NAME}") ]]; then
> +               ACCT_USER_ALREADY_EXISTS=yes
> +       fi
> +       readonly ACCT_USER_ALREADY_EXISTS
> +}

I don't think this pkg_setup function is necessary; you could do this
in pkg_preinst instead, before enewuser gets called.