[node-devel] CIM plugin for oVirt Node

[Perry Myers]

> Let me start out by saying that I know almost nothing about CIM so I'm
> largely talking out of my....

"..." is code for "secret love for CIM" right?  :)

> I think the first question to answer is why we're adding CIM to oVirt
> node in the first place.
> 
> Is the goal to expose a specific DMTF schema for on-node management?  Is
> it to allow arbitrary third-party CMPI providers to be added for
> hardware management?  Is it to allow third party CIM management suites
> to see and manage ovirt-node instances?

Those are good questions, none of which I have context/answers for :)

I think there are some different paths we could take here (not
necessarily mutually exclusive)

1. Expose providers for nominal read-only access so that existing
   monitoring solutions can leverage CIM at least for getting system
   state

2. Get someone to write vdsm-cim which exposes a subset of standard CIM
   API calls but processed through vdsm so that we don't end up having
   split brain

3. Enable providers in read-write mode for usages of oVirt Node where
   oVirt Engine is not involved (single node use case)

As an aside, this is the reason why we want to add this functionality as
a plugin vs. making it integral into the Node.  We don't see/think that
everyone will find it useful, so it'll be smth optional rather than
required.

> For just about any of these, if the answer isn't qualified with
> "exclusively for use by ovirt-engine", how is a split brain going to be
> avoided?

For libvirt-cim we planned on making it so you could only call the
read-only functions.  I forget the details here, but iirc we did do some
testing to make sure that read-only access from libvirt-cim to libvirtd
worked properly.  DV might recall...

> I think the provider needs ultimately will determine what cimmon is
> necessary.
> 
> Just to further complicate things, most providers these days are still
> only 32-bit as I understand it...

I think right now the only concrete thing we're going to add is
libvirt-cim, which does have 64bit version