[openstack-dev] [keystone][congress][group-policy] Fetching policy from a remote source

Doug Hellmann doug at doughellmann.com
Mon Mar 16 19:24:41 UTC 2015

Excerpts from Adam Young's message of 2015-03-16 14:17:16 -0400:
> On 03/16/2015 01:45 PM, Doug Hellmann wrote:
> > All of these are reasons we have so far resisted building a service to
> > deploy updates to oslo.config's input files, and rely on provisioning
> > tools to update them.
> >
> > Have we consider using normal provisioning tools for pushing out
> > changes to policy files, and having the policy library look at the
> > timestamp of the file(s) to decide if it needs to re-read them
> > before evaluating a rule? Maybe we wouldn't always scan the file
> > system, but wait for some sort of signal that the scan needs to be
> > done.
> I like this last idea.  Thew trigger needs to be app specific, I think.

I was thinking of a callback to be triggered by 'kill -HUP $pid'. We can
make a little framework for registering callbacks on signals (if there
isn't something like that already) to allow multiple refresh actions on
the signal.

> >
> > Doug
> I think policy files are not config files.  We've treated them as such 
> in the past as they are not dynamic, but I don't think I want to *have* 
> to do this:
> 1.  Change policy in keystone (somehow)
> 2.  Tell Puppet that there is a new file
> 3.  Have puppet pick up the3 new file and sync it to the servers.

Right, I wouldn't do that. I would modify the file in my puppet
repository and then push that out all at once. Keystone would receive
the policy files the same way as the other services.

> Although I would say that we should make it easy to support this workflow.
> For one thing, it assumes that all of the comsuers are talking to the 
> same config management system, which is only true for a subset of the 
> services.

I'm not sure what you mean here. Do you mean that in a given deployment
you would expect some services to be configured by puppet and others to
be configured a different way?

> I see a case for doing this same kind of management for Many of the 
> files Keystone produces.  Service catalog is the most obvious candidate.

Yes, that's another good example, although in that case we do already
have an API that lets a cloud consumer access the service catalog data
so it might be viewed as different from the policy rules or oslo.config
files (the latter at least typically have private data we wouldn't want
to share through an API).

> If we could have a workflow for managing : PKI certs, Federatiomn 
> mappings and  (Group only?) Role Assignments we could decentralize token 
> validation.
> When doing the PKI tokens, we discussed this, and ended up with a t 
> "fetch first" policy toward the certs.
> Puppet does not know how to get a token, so it can't call the keystone 
> token-protected APIs to fetch new data.  What forms of authentication do 
> the config managment systems support?  Is this an argument for tokenless 
> operations against Keystone?

In my scenario puppet (or chef or whatever) is the source of truth for
the configuration file, not one of our services. So there's no need for
the configuration management tool to talk to any of our services beyond
sending the HUP signal telling us to re-read the file(s).



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