[openstack-dev] [heat][keystone] APIs, roles, request scope and admin-ness

Steven Hardy shardy at redhat.com
Thu Nov 14 17:43:07 UTC 2013

On Thu, Nov 14, 2013 at 10:20:02AM -0600, Dolph Mathews wrote:
> On Sat, Nov 2, 2013 at 11:06 AM, Steven Hardy <shardy at redhat.com> wrote:
> > Hi all,
> >
> > Looking to start a wider discussion, prompted by:
> > https://review.openstack.org/#/c/54651/
> > https://blueprints.launchpad.net/heat/+spec/management-api
> > https://etherpad.openstack.org/p/heat-management-api
> >
> > Summary - it has been proposed to add a management API to Heat, similar in
> > concept to the admin/public API topology used in keystone.
> > I'm concerned that this may not be a pattern we want to propagate
> > throughout
> > OpenStack, and that for most services, we should have one API to access
> > data,
> > with the scope of the data returned/accessible defined by the roles held by
> > the user (ie making proper use of the RBAC facilities afforded to us via
> > keystone).
> >
> Agree with the concern; Identity API v3 abandons this topology in favor of
> more granular access controls (policy.json) on a single API.
> From an HTTP perspective, API responses should vary according to the token
> used to access the API. Literally,
>   Vary: X-Auth-Token
> in HTTP headers.
> >
> > In the current PoC patch, a users admin-ness is derived from the fact that
> > they are accessing a specific endpoint, and that policy did not deny them
> > access to that endpoint.  I think this is wrong, and we should use keystone
> > roles to decide the scope of the request.
> >
> ++ (although use of the word "scope" here is dangerous, as I think you mean
> something different from the usual usage?)

I was using "scope" to say the context of the request can affect what data
is returned, ie the filters we apply when processing it.

> > The proposal seems to consider tenants as the top-level of abstraction,
> > with
> > the next level up being a global service provider admin, but this does not
> > consider the keystone v3 concept of domains [1]
> v3 also allows domain-level roles to be inherited to all projects owned by
> that domain, so in effect-- it does (keystone just takes care of it).

Ok, thanks, that's useful info

> > , or that you may wish to
> > provide some of these admin-ish features to domain-admin users (who will
> > adminster data accross multiple tenants, just like has been proposed), via
> > the
> > public-facing API.
> >
> > It seems like we need a way of scoping the request (via data in the
> > context),
> > based on a heirarchy of admin-ness, like:
> >
> > 1. Normal user
> >
> I assume "normal" user has some "non-admin" role on a project/tenant.

Yep, that's my assumption, just not a role associated with admin-ness.

> > E.g what data can we add to move from X-Roles in auth_token, to
> > expressing roles in multiple tenants and domains?
> >
> Tokens can only be scoped to a single project or domain, so that's your
> mapping. All X-Roles apply to the X-Project or X-Domain in context. I don't
> think we have a good roadmap to support a single authenticated request with
> multi-project authorization. The best solution I have is to pass an
> unscoped token that can be rescoped to two or more projects as needed.
> Trust-based tokens are explicitly scoped already.

So this is a piece of the puzzle I was missing until now, combined with the
fact that Domain scoped tokens do not imply authorization with all projects
within that domain.  Thanks for the IRC conversation which cleared that up!

Based on this revised understanding, it sounds like, for now at least, some
of the global "management api" requirements may be best served via some
client tools which make multiple API calls to get the required information,
on behalf of a user who has the necessary roles to access all the projects.



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