[openstack-dev] [keystone] Suggested LDAP DIT for domains

Adam Young ayoung at redhat.com
Thu Apr 25 14:45:42 UTC 2013

OK,  so Ryan has convinced me that multiple LDAP servers under the same 
Keystone is an incantation for self induced insanity.

Based on conversations with the other devs, we are going to enforce that 
there is only one LDAP server per keystone, and limit the number of 
domains it can support to one.

There can be only one.

The APIs for Domains will still be implemented, but creating or 
modifying a domain will be return an Not implemented return code. There 
will be a single domain object that will be immutable, although we may 
allow initializing it from config file values.

Why are we "yanking" a feature like this? Quite simply, because the vast 
majority of LDAP deployments out there will not use it, and will not 
support the approach we have started.  We would rather focus on solving 
the real needs of the LDAP users.  Most people cannot write to their 
LDAP servers, and those that can often don't have the power to change 
the schema.  Thus far, the LDAP work has kept this design in mind, but 
Domains forced us to marry up two inconstant views of the world.

Multiple domains will still be supported in the SQL backend.

Organizations that require multiple LDAP servers were not served by the 
existing implementation.  Those will require a different solution. Each 
will get their own Keystone server, and we will use the approach 
sketched out in other blueprints to ensure that they can co-exist in a 
single Open Stack deployment.

On 04/24/2013 10:46 AM, Adam Young wrote:
> On 04/24/2013 09:00 AM, Simo Sorce wrote:
>> On Tue, 2013-04-23 at 15:26 -0700, Ryan Lane wrote:
>>> <https://docs.google.com/file/d/0B96SIvDkZEUJU1JoZE8xTWh4UFk/edit?usp=sharing> 
>>> In the above, everything exists under ou=domains. In the case an
>>> operator wants to use only one single (default) domain, they'd set
>>> their configuration to use the root, rather than ou=domains, and would
>>> move everything up a level. Otherwise, a default domain exists as a
>>> normal domain in the tree.
>>> In this DIT configuration, domains have roles and projects, projects
>>> have roles. Projects and roles have members. I believe there was
>>> discussion of implying membership in the project by membership of the
>>> roles. I'm not a huge fan of that, but I can modify this design if
>>> that's the preferred approach.
>>> There's some major benefits of designing the DIT in this way:
>>> 1. It's possible to scope searches by depth and base to limit searches
>>> to domains and project and to find roles for domains and projects.
>>> 2. The DIT can be extended by LDAP administrators for other uses. I
>>> can give you a ton of examples, as I'm doing this currently for
>>> per-project sudoers, service and group users, etc..
>>> 3. Users, groups, and projects have no requirements for being globally
>>> unique. They are only unique per domain.
>>> 4. For operators using the current implementation who don't want
>>> multiple domains, this is backwards compatible.
>>> 5. For operators wanting to using multiple domains, they simply need
>>> to move their tree a level deeper. Of course this isn't a simple
>>> change, but it should be a matter of configuration for their
>>> applications, rather than development effort.
>>> 6. Domains are a matter of hierarchy, and this uses LDAP's natural
>>> hierarchy.
>> It would be nice if this hierarchy were optional, for example you may
>> have attributes with substitution rules that tell where the base for a
>> domain is
>> Pseudo ini-style config:
>> [domain]
>> base = ou=%D,ou=domains
>> where %D is substituted with the domain name.
>> This would allow people to flexibly define their DITs.
>> Another option could be to spawn a separate driver per domain with a
>> template based configuration system (based again on substitutions), or a
>> per domain explicit configuration.
>> This way you could use either one or multiple LDAP servers at the same
>> time as each domain could have a completely different configuration.
>> Simo.
> I wrote up this blueprint in support of the "separate driver per 
> domain" approach:
> https://blueprints.launchpad.net/keystone/+spec/multiple-datastores
> Which gives us a way to register the drivers.  What it does not give 
> us is a domain registry.  I suspect that the right way to do a domain 
> registry would be to use a either a flat file driver or the SQL Driver 
> as the Identity driver, and have a way to link to other drivers for 
> the individual domains.  We could also put a domains section into the 
> config file, with a mapping of domain-id to driver, but that misses 
> all of the configuration options for each domain.
> I also started this blueprint for extracting the binding information 
> from the config file for LDAP:
> https://blueprints.launchpad.net/keystone/+spec/json-for-ldap
> Which is probably a dupe of:
> https://blueprints.launchpad.net/keystone/+spec/ldap-object-templates
> So we are thinking along the same ideas.
> However, David Chadwick's attribute mapping approach might be a better 
> solution for complex mappings from LDAP.  Kristy Siu had submitted it 
> back in decebmer, but it got nacked and abandoned.
> https://review.openstack.org/#/c/18280/
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