[openstack-dev] Fwd: keystone federation user story

Jamie Lennox jamielennox at gmail.com
Wed May 25 07:55:00 UTC 2016

On 25 May 2016 at 03:55, Alexander Makarov <amakarov at mirantis.com> wrote:

> Colleagues,
> here is an actual use case for shadow users assignments, let's discuss
> possible solutions: all suggestions are appreciated.
> ---------- Forwarded message ----------
> From: Andrey Grebennikov <agrebennikov at mirantis.com>
> Date: Tue, May 24, 2016 at 9:43 AM
> Subject: keystone federation user story
> To: Alexander Makarov <amakarov at mirantis.com>
> Main production usecase:
> As a system administrator I need to create assignments for federated users
> into the projects when the user has not authenticated for the first time.
> Two different approaches.
> 1. A user has to be assigned directly into the project with the role
> Role1. Since shadow users were implemented, Keystone database has the
> record of the user when the federated user authenticates for the first
> time. When it happens, the user gets unscoped token and Keystone registers
> the user in the database with generated ID (the result of hashing the name
> and the domain). At this point the user cannot get scoped token yet since
> the user has not been assigned to any project.
> Nonetheless there was a bug
> https://bugs.launchpad.net/keystone/+bug/1313956 which was abandoned, and
> the reporter says that currently it is possible to assign role in the
> project to non-existing user (API only, no CLI). It doesn't help much
> though since it is barely possible to predict the ID of the user if it
> doesn't exist yet.
> Potential solution - allow per-user project auto-creation. This will allow
> the user to get scoped token with a pre-defined role (should be either
> mentioned in config or in mapping) and execute operations right away.
> Disadvantages: less control and order (will potentially end up with
> infinite empty projects).
> Benefits: user is authorized right away.

This is something that has come up a few times as a workflow problem. For
some group of users you should end up with your own project that doesn't
exist until the first time you log in. This is something i think we could
extend the mapper to handle. It wouldn't be user authenticated immediately,
just solve the workflow of personal projects.

> Another potential solution - clearly describe a possibility to assign
> shadow user to a project (client should generate the ID correctly), even
> though the user has not been authenticated for the first time yet.
> Disadvantages: high risk of administrator's mistake when typing user's ID.
> Benefits: user doesn't have to execute first dummy authentication in order
> to be registered.

I would prefer not to do this. It either involves creating a user and then
somehow associating what federated information they will present with
later, or allowing you to create a user with a predetermined or predictable
id. I dont think we should add either of those APIs.

> 2. Operate with the groups. It means that the user is a member of the
> remote group and we propose the groups to be assigned to the projects
> instead of the users.
> There is no concept of shadow groups yet, so it still has to be
> implemented.
> Same problem - in order to be able to assign the group to the project
> currently it has to exist in Keystone database.

I'm not sure what you want for shadow groups here. Groups are always a
keystone concept, they have never been ephemeral in the way that federated
users used to be. Are you wanting  to make it so that keystone groups are
auto created?

Mapping federated users into groups has always been the way federation was
designed in keystone because even though you can't know the actual users
that are going to log in, it is very likely they fall into something that
can fairly easily be categorized by looking at the roles that come in from
the IDP assertion. So your mapping does something like "if user has the
admin role put them in the federated-admin group", the federated-admin
group has already been established and already has roles on a number of
projects. Users are then automatically granted those roles on those
projects. You could go so far as to check for user names in the mapping
here but that's not a sustainable solution.

> It should be either allowed to pre-create the project for a group (based
> on some specific flags in mappings),

maybe - if you created the groups why don't you know the projects they are
going to be in?

> or it should be allowed to assign non-existing groups into the projects.

still not sure on this non-existing groups concept.

> I'd personally prefer to allow some special attribute to be specified in
> either the config or mapping which will allow project auto-creation.
> For example, user is added to the group "openstack" in the backend. In
> this case this group is the part of SAML assertions (in case when SAML2 is
> used as the protocol), and Keystone should recognize this group through the
> mapping. When user makes login attempt, Keystone should pre-create the
> project and assign pre-defined role in it. User gets access right away.
So yea, i'm interested in why the current federation mapping users to
groups isn't what you're asking for? I can see the auto create project for
user case, but i'm struggling to see why you would want to auto create
projects for groups of users you didn't set up.

> --
> Andrey Grebennikov
> Deployment Engineer
> Mirantis Inc, Mountain View, CA
> --
> Kind Regards,
> Alexander Makarov,
> Senior Software Developer,
> Mirantis, Inc.
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