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Re: nova/puppet blueprint, and some questions
Thanks for your comments. I'm going to start with a screenshot for context:
That's what it looks like when you configure an instance using Open
Stack Manager, which is WikiMedia's VM management interface. My main
priority for adding puppet support to Nova is to facilitate the creation
and control of a GUI much like that one.
On 1/26/12 5:03 PM, Andrew Clay Shafer wrote:
This sounds intriguing, but I'll plead ignorance here; can you tell me
more about what this would look like, or direct me to an existing
I'd also like to see more of a service oriented approach and avoid
adding tables to nova if possible.
I'm not sure the best solution is to come up with a generic service
for $configuration_manager for nova core. I'd rather see these
implemented as optional first class extensions.
What are you going to inject into the instances exactly? Where does
the site.pp live?
This is the question I'm hoping to get feedback on. Either nova can
generate a fully-formed site.pp and inject that, or it can pass config
information as metadata, in which case an agent would need to be running
on the guest which would do the work of generating the site.pp. I
certainly prefer the former but I'm not yet clear on whether or not file
injection is widely supported.
I haven't thought about this that much yet, but off the top of my
head, but if the instances already have puppet clients and are
configured for the puppet master, then the only thing you should need
to interact with is the puppet master.
It's definitely the case that all of this could be done via LDAP or the
puppet master and involve no Nova action at all; that's how WikiMedia's
system works now. My aim is to consolidate the many ways we currently
interact with instances so that we delegate as much authority to Nova as
possible. That strikes me as generally worthwhile, but you're welcome
to disagree :)
I'm not a fan of the Available, Unavailable, Default, particularly
because you are managing state of something that may not be true on
the puppet master.
I may be misunderstanding you, or my blueprint may be unclear.
Available, Unavailable, and Default don't refer to the availability of
classes on the puppet master; rather, they refer to whether or not a
class is made available to a nova user for a given instance. An
'available' class would appear in the checklist in my screenshot. An
Unavailable class would not. A 'default' class would appear, and be
pre-checked. In all three cases the class is presumed to be present on
the puppet master.
I also think managing a site.pp is going to be inferior to providing
an endpoint that can act as an eternal node tool for the puppet master.
In which case nova would interact directly with the puppet master for
configuration purposes? (I don't hate that idea, just asking for
I believe this (and your subsequent question) falls under the heading of
" Instances are presumed to know any puppet config info they need at
creation time (e.g. how to contact the puppet master). " Important, but
outside the scope of this design :)
One other point, that you might have thought of, but I don't see
anywhere on the wiki is how to handle the ca/certs for the instances.
Just to reiterate, I'd love to see deeper configuration management
integrations (because I think managing instances without them is it's
own hell), but I'm not convinced it should be part of core nova per se.
So that I understand your terminology... are extensions like the quotas
or floating ips considered 'core nova'?
Thanks again for your input! Clearly it would be best to hash this out
at the design summit, but I'm hoping to get at least a bit of coding
done before April :)