Open Stack

Bringing conversation for domains in Keystone to the broader mailing lists.


On Oct 26, 2012, at 5:18 AM, Dolph Mathews <dolph.mathews at gmail.com> wrote:
> I think this discussion would be great for both mailing lists.
> 
> -Dolph
> 
> 
> On Fri, Oct 26, 2012 at 5:18 AM, Henry Nash <henry.nash at mac.com> wrote:
> Hi
> 
> <Not sure where best to have this discussion - here, as a comment to the v3api doc, or elsewhere - appreciate some guidance and will transfer this to the right place>
> 
> At the Summit we started a discussion on whether things like user name, tenant name etc. should be globally unique or unique within a domain.  I'd like to widen that discussion to try and a) agree a direction, b) agree some changes to our current spec. Here's my view as an opening gambit:
> 
> - When a Keystone instance is first started, there is only one, default, Domain.  The Cloud Provider does not need to create any new domains, all projects can exist in this default domain, as will the users etc.  There is one, global, name space.  Clients using the v2 API will work just fine.
> 
> +1

Very much what we were thinking for the initial implemenation and rollout to make it backwards "compatible" with the V2 (non-domain) core API

> - If the Cloud Provider wants to provide their customers with regions they can administer themselves and be self-contained, then they create a Domain for each customer.  It should be possible for users/roles to be scoped to a Domain so that (effectively) administrative duties can be delegated to some users in that Domain.  So far so good - all this can be done with the v3 API.
> 
> Not clear on if you're referring to endpoint regions, or just describing domain isolation?

I believe you're describing the key use cases behind the domains mechanism to begin with - user and project partitioning to allow for administration of those to be clearly "owned" and managed appropriately.


> - We still have work to do to make sure items in other OS projects that reference tenants (e.g. Images) can take a Domain or Project ID, but we'll get to that soon enough
> 
> Everything will continue to work with projects, but once middleware starts providing a DOMAIN_ID and DOMAIN_NAME to the underlying service, it'll be up to them to take advantage of it. Images per domain is an excellent example use case.

>  
> - However, Cloud Providers want to start enabling enterprise customers to run more and more of the workloads in OpenStack clouds - over and above, the smaller sized companies that are doing this today.  For this to work, the encapsulation of a Domain need, I think, to be able to be stricter - and this is where the name space comes into play.  I think we need to allow for a Domain to have its own namespace (i.e. users, roles, projects etc.) as an option.  I see this as a first step to allowing each Domain to have its own AuthZ/N service (.e.g external ldap owned and hosted by the customer who will be using the Domain)
> 
> Implementation:
> 
> - A simplistic version would just allow a flag to specified on Domain creation that said whether this a "private" or "shared" Domain.  Shared would use the current global name space (and probably be the default for compatibility reasons).
> 
> I like the direction of this -- need to digest implications :)

I like the idea conceptually - but let's be clear on the implications to the end users:

Where we're starting is preserving a global name space for project names and user names. Allowing a mix of segregated and global name spaces imposes a burden of additional data being needed to uniquely place authentication and authorization.

We've been keeping to 2 key pieces of info (username, password) to get authenticated - and then (via CLI or Horizon dashboard) you can choose from a list of protential projects and carry on. In most practical circumstances, any user working primarily from the CLI is already providing 3-4 pieces of information:

* username
* password
* tenant name
* auth_url

to access and use the cloud.

By allowing domains to be their own namespaces, we're adding another element that will be absolutely required to identify the person authenticating:
 * domain name

implying a cascade of changes to the user experience all the way down through horizon.


> - A more flexible approach would be to allow the specification of where the various sub-services of Keystone (e.g. AuthN/Z, Service Catalogue, Resources (i.e Users, Projects)) are hosted.  The defaults would all point back to the default domain (i.e. are global and shared), but instead could be specified as "self" (I.e. the new Domain), or, in the future, some other external location, e.g. for a remote ldap.
> - As an aside, this multi-name space model could also allow the Cloud Provider their own name space, separate from their customers - i.e. they will have a need to create admins who can just create domains and on-board customers into those domains.  These users & roles could exist in the default domain, while all the customers' users/roles exist solely within their own domains.
> - One potential problem I do see is with roles.  Today, the role name is, if I understand it correctly, a kind of shared secret between, other services and Keystone - e.g. it is the actual name of a given role, say "ProjectAdmin" , that must match in, say, the Nova policy file and the role assignment in Keystone (please correct me if I have this wrong).
> 
> You're 100% correct.
>  
> How would that work if the role names were not unique across Domains?
> 
> Not that we would want admins to ever see Role ID's, or edit policy files with role ID's, but they provide a potential solution.

The different role names would need to be accounted for in the policy files the way they're set up today - the enforcement there is all at the service level. There's no current provision for evaluating policy differently based on domain. While that's possible, it sounds like a tremendous cascade of additional complication, as the policy, and roles, are all set up and managed by deployers.

I think this might be an interesting addition in the future, but want to keep the initial implementation and roll-out of the policy mechanisms and domains consistent and simple for a first roll-out iteration.

> What is the desired functionality for a Cloud Provider wanting to give their enterprise customers this level of flexibility - will they have dedicated Nova endpoints anyway?  Sounds too rigid.  This might tie into another bp we are working on at IBM in terms of using Availability zones to allow Cloud Providers to divide up their compute resources in a more flexible way.
> - Finally, I wanted to raise the subject of whether we should make it a goal to remain compatible with the v2 API once the cloud provider starts creating additional domains.
> 
> Joe and I briefly discussed this at the summit. As a migration to v3, we'd obviously be creating the default domain and mapping all existing users/projectse/etc to it. I'd be fine if the v2 implementation ONLY interacted with resources in that default domain; i.e. if you want to use domains, upgrade to a v3 client.
>  
> As stated above, if just the default domain is being used, then fine.  And while I agree that, technically, the v2 API should still work with the above if all the other domains point back to the default domain for their sub-services - it feels overly flexible (and maybe wrong conceptually) to support v2 semantics across a multi-domain installation.
> 
> +1
> 
> 
> Interested in everyone else's view.
> 
> Henry
> 
> 

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