----- Original Message -----
> From: "Deepak C Shetty" <deepa...@linux.vnet.ibm.com>
> To: "Ryan Harper" <ry...@us.ibm.com>
> Cc: "Saggi Mizrahi" <smizr...@redhat.com>, "Anthony Liguori"
> <aligu...@redhat.com>, "VDSM Project Development"
> <vdsm-devel@lists.fedorahosted.org>
> Sent: Tuesday, June 19, 2012 10:58:47 AM
> Subject: Re: [vdsm] [virt-node] VDSM as a general purpose virt host manager
>
> On 06/19/2012 01:13 AM, Ryan Harper wrote:
> > * Saggi Mizrahi<smizr...@redhat.com> [2012-06-18 10:05]:
> >> I would like to put on to the table for descussion the growing
> >> need for a way
> >> to more easily reuse of the functionality of VDSM in order to
> >> service projects
> >> other than Ovirt-Engine.
> >>
> >> Originally VDSM was created as a proprietary agent for the sole
> >> purpose of
> >> serving the then proprietary version of what is known as
> >> ovirt-engine. Red Hat,
> >> after acquiring the technology, pressed on with it's commitment to
> >> open source
> >> ideals and released the code. But just releasing code into the
> >> wild doesn't
> >> build a community or makes a project successful. Further more when
> >> building
> >> open source software you should aspire to build reusable
> >> components instead of
> >> monolithic stacks.
> >>
> > Saggi,
> >
> > Thanks for sending this out. I've been trying to pull together
> > some
> > thoughts on what else is needed for vdsm as a community. I know
> > that
> > for some time downstream has been the driving force for all of the
> > work
> > and now with a community there are challenges in finding our own
> > way.
> >
> > While we certainly don't want to make downstream efforts harder, I
> > think
> > we need to develop and support our own vision for what vdsm can be
> > come,
> > some what independent of downstream and other exploiters.
> >
> > Revisiting the API is definitely a much needed endeavor and I think
> > adding some use-cases or sample applications would be useful in
> > demonstrating whether or not we're evolving the API into something
> > easier to use for applications beyond engine.
> >
> >> We would like to expose a stable, documented, well supported API.
> >> This gives
> >> us a chance to rethink the VDSM API from the ground up. There is
> >> already work
> >> in progress of making the internal logic of VDSM separate enough
> >> from the API
> >> layer so we could continue feature development and bug fixing
> >> while designing
> >> the API of the future.
> >>
> >> In order to achieve this though we need to do several things:
> >> 1. Declare API supportability guidelines
> >> 2. Decide on an API transport (e.g. REST, ZMQ, AMQP)
> >> 3. Make the API easily consumable (e.g. proper docs, example
> >> code, extending
> >> the API, etc)
> >> 4. Implement the API itself
> > I agree with the list, but I'd like to work on the redesign
> > discussion so
> > that we're not doing all of 1-4 around the existing API that's
> > engine-focused.
> >
> > I'm over due for posting a feature page on vdsm standalone mode,
> > and I
> > have some other thoughts on various uses.
> >
> > Some other paths of thought for use-cases I've been mulling over:
> >
> > - Simplifying using QEMU/KVM
> > - consuming qemu via command line
> > - can we manage/support developers launching qemu
> > directly
> > - consuming qemu via libvirt
> > - can we integrate with systems that are already using
> > libvirt
> >
> > - Addressing issues with libvirt
> > - are there kvm specific features we can exploit that
> > libvirt
> > doesn't?
> >
> > - Scale-up/fail-over
> > - can we support a single vdsm node, but allow for
> > building up
> > clusters/groups without bringing in something like
> > ovirt-engine
> > - can we look at decentralized fail-over for reliability
> > without
> > a central mgmt server?
> >
> > - pluggability
> > - can we support an API that allows for third-party
> > plugins to
> > support new features or changes in implementation?
>
> Pluggability feature would be nice. Even nicer would be the ability
> to
> introspect and figure whats supported by VDSM. For eg: It would be
> nice
> to query what plugins/capabilities are supported and accordingly the
> client can take a decision and/or call the appropriate APIs w/o
> worrying
> about ENOTSUPP kind of error.
> It does becomes blur when we talk about Repository Engines... that
> was
> also targetted to provide pluggaibility in managing Images.. how will
> that co-exist with API level pluggability ?
>
> IIUC, StorageProvisioning (via libstoragemgmt) can be one such
> optional
> support that can fit as a plug-in nicely, right ?
You will have have an introspective verb to get supported storage engines.
Without the engine the hosts will not be able to log in to an image repo but it
will not be an API level error. You will get UnsupportedRepoFormatError or
something similar no matter which version of VDSM you use. The error is part of
the interface and engines will expose their format and parameter in some way.
>
> > - kvm tool integration into the API
> > - there are lots of different kvm virt tools for various
> > tasks
> > and they are all stand-alone tools. Can we integrate
> > their
> > use into the node level API. Think libguestfs,
> > virt-install,
> > p2v/v2v tooling. All of these are available, but there
> > isn't an
> > easy way to use this tools through an API.
> >
> > - host management operations
> > - vdsm already does some host level configuration (see
> > networking e.g.) it would be good to think about
> > extending
> > the API to cover other areas of configuration and updates
> > - hardware enumeration
> > - driver level information
> > - storage configuration
> > (we've got a bit of a discussion going around
> > libstoragemgmt here)
> >
> > - performance monitoring/debugging
> > - is the host collecting enough information to do
> > debug/perf
> > analysis
> > - can we support specific configurations of a host that
> > optimize
> > for specific workloads
> > - and can we do this in the API such that
> > third-parties can
> > supply and maintain specific workload configurations
> >
> >> All of these are dependent on one another and the permutations are
> >> endless.
> >> This is why I think we should try and work on each one separately.
> >> All
> >> discussions will be done openly on the mailing list and until the
> >> final version
> >> comes out nothing is set in stone.
> >>
> >> If you think you have anything to contribute to this process,
> >> please do so
> >> either by commenting on the discussions or by sending
> >> code/docs/whatever
> >> patches. Once the API solidifies it will be quite difficult to
> >> change
> >> fundamental things, so speak now or forever hold your peace. Note
> >> that this is
> >> just an introductory email. There will be a quick follow up email
> >> to kick start
> >> the discussions.
> >
> >
> >> _______________________________________________
> >> vdsm-devel mailing list
> >> vdsm-devel@lists.fedorahosted.org
> >> https://fedorahosted.org/mailman/listinfo/vdsm-devel
>
>
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