Hi Adam,

So a comprehensive write-up...although I'm not sure we have made the case for 
why we need a complete rewrite of how policy is managed.  We seemed to have 
lept into a solution without looking at other possible solutions to the 
problems we are trying to solve.  Here's a start at an alternative approach:

Problem 1: The current services don't use the centralised policy store/fetch of 
keystone, meaning that a) policy file management is hard, and b) we can't 
support the policy-per-endpoint style of working
Solution: Let's get the other services using it!  No code changes required in 
Keytsone.  The fact that we haven't succeeded before, just means we haven't 
tried hard enough.

Problem 2: Different domains want to be able to create their own "roles" which 
are more meaningful to their users...but our "roles" are global and are 
directly linked to the rules in the policy file - something only a cloud 
operator is going to want to own.
Solution: Have some kind of domain-scoped role-group (maybe just called 
"domain-roles"?) that a domain owner can define, that maps to a set of 
underlying roles that a policy file understands (see: 
https://review.openstack.org/#/c/133855/). [As has been pointed out, what we 
are really doing with this is finally doing real RBAC, where what we call roles 
today are really capabilities and domain-roles are really just roles].  As this 
evolves, cloud providers could slowly migrate to the position where each 
service API is effectively a role (i.e. a capability) and at the domain level 
there exists the "abstraction that makes sense for the users of that domain" 
into the underlying capabilities. No code changes...this just uses policy files 
as they are today (plus domain-groups) - and tokens as they are too. And I 
think that level of functionality would satisfy a lot of people. Eventually (as 
pointed out by samuelmz) the policy "file" could even simply become the 
definition of the service capabilities (and whether each capability is "open", 
"closed" or "is a role")...maybe just registered and stored in the service 
entity the keystone DB (allowing dynamic service registration). My point being, 
that we really didn't require much code change (nor really any conceptual 
changes) to get to this end point...and certainly no rewriting of policy/token 
formats etc.  [In reality, this last point would cause problems with token size 
(since a broad admin capability would need a lot of capabilities), so some kind 
a collections of capabilities would be required.]

Problem 3: A cloud operator wants to be able to enable resellers to white label 
her services (who in turn may resell to others) - so needs some kind of 
inheritance model so that service level agreements can be supported by policy 
(e.g. let the reseller give the support expert from the cloud provider have 
access to their projects).
Solution: We already have hierarchical inheritance in the works...so that we 
would allow a reseller to assign roles to a user/group from the parent onto 
their own domain/project. Further, domain-roles are just another thing that can 
(optionally) be inherited and used in this fashion.

My point about all the above is that I think while what you have laid out is a 
great set of steps....I don't think we have conceptual agreement as to whether 
that path is the only way we could go to solve out problems.

On 18 Nov 2014, at 23:40, Adam Young <ayo...@redhat.com> wrote:

> There is a lot of discussion about policy.  I've attempted to pull the 
> majority of the work into a single document that explains the process in a 
> step-by-step manner:
> http://adam.younglogic.com/2014/11/dynamic-policy-in-keystone/
> Its really long, so I won't bother reposting the whole article here.  
> Instead, I will post the links to the topic on Gerrit.
> https://review.openstack.org/#/q/topic:dynamic-policy,n,z
> There is one additional review worth noting:
> https://review.openstack.org/#/c/133855/
> Which is for "private groups of roles"  specific to a domain.  This is 
> related, but not part of the critical path for the things I wrote above.
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