Open Stack

On 05/05/2015 12:20 PM, Colleen Murphy wrote:
> I'm cross-posting to the dev list since this conversation should be 
> happening there and is related to another thread there.

Ok.  I'm not replying puppet-openstack.

> I'm going to top-post a summary and then respond inline.
>
> The summary so far is that puppet-openstacklib provides a way to pass 
> in credentials to an API-driven puppet type via an auth parameter[1] 
> included in the types like so[2]. The benefit of this is that a user 
> could create additional API resources, such as keystone_user, by 
> passing in credentials directly to the type (presumably via hiera) 
> without having to read credentials out of keystone.conf. The desire 
> for something like this was outlined in the initial aviator 
> blueprint[3] (the openstackclient blueprint[4] changed some of the 
> design parameters, but not that one).
>
> self.instances and self.prefetch are class methods provided by puppet 
> that types and providers typically override. These methods are unable 
> to read type parameters, as far as I can tell, because they do not 
> have a specific instance from which to look up those parameters. In 
> our implementation, self.instances exists so that the command `puppet 
> resource keystone_user` works and returns a list of keystone_users, 
> and we don't use self.prefetch. So, the way the providers are intended 
> to work right now is: when creating a single resource, to run a custom 
> 'instances' object method to list resources and check for existence, 
> which can use username/password credentials passed in to the resource 
> OR use username/password credentials set as environment variables OR 
> fall back to reading admin_token credentials from keystone.conf, as it 
> always did; when run in `puppet resource` mode, it runs self.instances 
> which can only use credentials set as environment variables or read 
> credentials from keystone.conf since it has no way to accept an auth 
> parameter.
>
> There are a couple of problems with this approach, one outlined by 
> Gilles below and another that I'm just noticing.
>
> On Mon, May 4, 2015 at 8:34 PM, Gilles Dubreuil 
> <gil.dubreuil at gmail.com <mailto:gil.dubreuil at gmail.com>> wrote:
>
>     Hi Colleen,
>
>     The issue is about having to deal with 2 different code paths
>     because authentication could be optionally passed to a resource
>     instance where it can't when dealing with self.instances.
>     Its creates many complications down the road.
>     I initially expressed that from a technical OO point of view,
>     although as you said it doesn't really matter.
>     So, let's look at those examples:
>     https://review.openstack.org/#/c/178385/3/lib/puppet/provider/keystone.rb
>     https://review.openstack.org/#/c/178456/6/lib/puppet/provider/keystone_endpoint/openstack.rb
>
>     Providers should not have to go through that.
>
> That is indeed pretty awful, I had no idea this would get so 
> complicated when I initially wrote this.

I don't believe the final implementation will be that bad.  I don't 
think we have to support v2 any more.  We will just assume we always 
have enough information to use v3 auth and v3 api.  Based on our 
discussions here and on IRC, this is possible and is desireable.

>
> I'm also noticing what looks like a major flaw in that the object 
> instances method seems almost entirely useless. A resource looks up 
> the full list of resources but only ever stores one[5]. So the goal of 
> replacing self.prefetch with an object method that had access to the 
> auth params is just not accomplished at all.
>
>
>     This is why I think avoiding passing authentication details in
>     some case (instance) should be avoided.
>     The authentication is provided by another layer, basically the
>     environment, whether that comes from.
>
> Given the added complexity that you pointed out and the fact that the 
> motivation behind some of that complexity is moot, I'm inclined to 
> agree. We could avoid this complexity and be be able to take advantage 
> of self.prefetch (which should speed up performance) if we did away 
> with the auth parameter and the methods needed to accommodate that 
> parameter.
>
> The modules do not use that auth parameter themselves, it's intended 
> as an add-on if users wanted to include extra keystone_user, etc, 
> resources in their profiles and didn't want to worry about running it 
> on the keystone node. I rather doubt anyone is actually using that 
> yet, and I'm curious if anyone has a desire to keep it around.

I cannot figure out a use case for having per-resource authentication 
parameters.  It seems that the likely use case would be for per-run auth 
parameters, set via env. or config file.

However, in openstack.rb self.request - what if self.request were 
changed to do the same thing as the instance request method?

>
> So if the providers could both read a config file (keystone.conf, 
> glance-api.conf, etc) and read environment variables for 
> authentication, would that be desireable?

Yes.

>
> The auth param can accept a path to an openrc file, but if we just 
> assumed a certain path we could have the provider check that for 
> credentials as well. puppet-openstack_extras happens to place it in 
> /root/openrc[6].

Yes.  It would be nice to have a fallback path if there is no 
resource[:auth]['openrc']

>
>     Don't get me wrong the new openstacklib is great but the
>     authentication being different between class and instances.
>     Again, the authentication should be the same for the a whole
>     provider, unconditionally.
>     Otherwise, sure it works, I don't know how to put it, honestly, it
>     breaks the spirit of the providers.
>
>     Richm, imcsk8, and I have discussed around that issue (keystone
>     v2/v3 support) and decided to talk to you before pushing anything,
>     but we do think this boulder to be removed.
>     By doing so we'll be able to move faster.
>
> Thanks for doing so. I'm glad we could have this discussion.
>
>
>     I'm in time zone UTC+10 - Will try tomorrow morning for me, arvo
>     for you.
>
>     Gilles
>     -- 
>
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>
>
> Colleen
>
> [1] 
> http://git.openstack.org/cgit/stackforge/puppet-openstacklib/tree/lib/puppet/util/openstack.rb
> [2] 
> http://git.openstack.org/cgit/stackforge/puppet-keystone/tree/lib/puppet/type/keystone_user.rb#n85
> [3] 
> https://blueprints.launchpad.net/puppet-openstacklib/+spec/use-aviator-in-module-resources
> [4] 
> https://blueprints.launchpad.net/puppet-openstacklib/+spec/use-openstackclient-in-module-resources
> [5] 
> http://git.openstack.org/cgit/stackforge/puppet-keystone/tree/lib/puppet/provider/keystone_user/openstack.rb#n212
> [6] 
> http://git.openstack.org/cgit/stackforge/puppet-openstack_extras/tree/manifests/auth_file.pp#n86
>
>
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