Re: [gentoo-dev] Requirements for UID/GID management

[Patrick McLean <chutzpah@gentoo.org>]

On Sat, 28 Jan 2017 11:28:45 +0000
James Le Cuirot <chewi@gentoo.org> wrote:

> On Fri, 27 Jan 2017 18:37:52 -0800
> Patrick McLean <chutzpah@gentoo.org> wrote:
> 
> > I don't think we need to have stable UIDs/GIDs in the "normal" case of
> > standalone users with a single Gentoo system at home. The people who
> > need predictable UIDs/GIDs are the "enterprise" users or the home users
> > who use things such as NFS. I work for a company that uses Gentoo, we
> > have a bunch of workarounds to make sure that UIDs and GIDs are
> > stable. To make something to solve our problem (and I suspect everyone
> > else who cares about this), it would be sufficient to have a mechanism
> > to override the default random assignment with a fixed UID/GID.
> > Possibly some file in /etc/portage or in the profile (or both) that
> > allows one to configure what UID/GID a user will get when the user is
> > being created. One advantage of this is that user.eclass could be
> > modified to support it, so we don't have to wait for a new EAPI before
> > taking advantage of it.  
> 
> Is this really a problem in enterprise? What are the workarounds you're
> using? NFS has long had idmapd, which takes care of this problem. I
> still find people shy away from NFSv4 but I've not had any trouble with
> it. There's also LDAP, usually coupled with sssd these days, in which
> case the users and groups are created just once on a central server.
> Samba with Active Directory effectively gives you the same thing and
> can also be coupled with sssd. I recently tried mixing Samba, sssd, and
> NFS, which was quite fascinating and surprisingly easy thanks to
> realmd. This allowed me to use NFS with Kerberos, which is something
> you really need in an enterprise environment.
> 

We are using both NFSv3 and NFSv4, the UID stability is also important
when you are using full-image deployments, and have local storage on
the system, you don't want the new OS to have different UIDs/GIDs than
the previous installation.

We are using file in /etc/portage/env that define a pre_pkg_setup that
creates the users before the standard pkg_setup does, with our stable
UID/GID for that system. We have to do this for each package that
creates a user that may be used to store stable data.