~ Scott
On Tue, Aug 6, 2013 at 6:12 AM, Patrick Petit <patrick.pe...@bull.net
<mailto:patrick.pe...@bull.net>> wrote:
Hi Dina and All,
Please see comments inline. We can drill down on the specifics
off-line if that's more practical.
Thanks in advance,
Patrick
On 8/5/13 3:19 PM, Dina Belova wrote:
Hello, everyone!
Patrick, Julien, thank you so much for your comments. As for the
moments Patrick mentioned in his letter, I'll describe our vision
for them below.
1) Patrick, thank you for the idea! I think it would be great to
add not only 'post-lease actions policy', but also 'start-lease
actions policy'. I mean like having two types of what can be done
with resource (virtual one) on lease starting - 'start VM
automatically' or 'start VM manually'. This means user may not
use reserved resources at all, if he needs such a behaviour.
Something along those lines would work but I think the 'start VM
manually' keeps over specifying the behavior IMO since you still
make the assumption that reserved resources are always started
using a term 'manually' that is misleading because if not
automatically started by the reservation service they can still be
automatically started elsewhere like in Heat. I general I agree
that users can take advantage of being able to specify pre and
post lease actions / conditions although it shouldn't be
prescriptive of something binary like start automatically or
manually. Another beneficial usage could be to send parametrized
notifications. I would also make the pre and post action optional
so that if the user choose not to associate an action with the
realization of a lease, he doesn't have to specify anything.
Finally, I would also that the specification of a pre and post
action is assorted of a time offset to take into account the lead
time to provision certain types of resources like physical hosts.
That's a possible solution to point 4.
2) We really believe that creating lease first, and going with
its id to all the OpenStack projects to use is a better idea than
'filling' the lease with resources just at the moment of its
creation. I'll try to explain why. First of all, as for virtual
reservations, we'll need to proxy Nova, Cinder, etc. APIs through
Reservation API to reserve VM or volume or something else.
Workflow for VM/volume/etc. creation is really complicated and
only services written to do this have to do it, in our opinion.
Second, this makes adding new reservations to the created lease
simple and user friendly. And the last moment, we should not copy
all these dashboard pages for instance/volume/... creation to the
reservation Dashboard tab in this case. As for the physical
reservations, as you mentioned, there is no way to 'create' them
like virtual resources in the Nova's, for example, API now.
That's why there are two ways to solve this problem and reserve
them. First way is to reserve them from Reservation Service as it
is implemented now and described also in our document (WF-2b part
of it). The second variant (that seems to be more elegant, but
more complicated as well) is to implement needed parts as Nova
API extension to let Nova do the things it does the best way -
managing hosts, VMs, etc. Our concern in this question is not
doing things Nova (or any other service) can do much better.
Well, I am under the impression that you put forward an
argumentation that is mostly based on an implementation artifact
which takes advantage of the actual resource provisioning workflow
and dashboard rather than taking into account the most common use
cases and practices. There maybe use cases that mandate for an
iterative workflow that is similar to what you describe. I may be
wrong, but I am doubtful it is going to be a common use case. We
tend to think of AWS as being a reference and you've probably
noticed that reservations in AWS are performed by chunk (the more
I reserve for the longer period of time, the cheaper). The problem
with adding reservations into a lease on a continuous basis is
that as a user I may end up undo what I have done (e.g. I got only
900 out of the 1000 VMs I want) and keep trying forever. That's
potentially a lot of overhead. Also, as a cloud operator, I'd like
to know what my reservation pipeline looks like ahead of time so
that I can provision new hardware in due time. That's capacity
planning. As an operator, I also want to be able grant
reservations and charge for it even if I don't have the capacity
right now provided the lead time to provisioning new hardware
doesn't conflict with the terms of the pending leases. If a user
can add reservations to a lease at the last moment, that
flexibility may be compromised. In any events, this is how we
envision the behavior of the reservation service for the
reservation of physical capacity and so, it is important the
service API can support that interaction model. I think it's
probably okay to do it in two separate steps 1) create the lease,
2) add reservation (although it seems problematic in the case of
immediate lease) but the actual hosts reservation request should
include a cardinality factor so that if the user wants to reserve
x number of hosts in one chunk he can do it. The reservation
service would respond yes or no depending on the three possible
lease terms (immediate, best effort and schedule) along with the
operator's specific reservation policies that yet has to be
configurable one way or another. To be discussed...
3) We completely agree with you! Our 'nested reservation' vision
was created only to let user the opportunity of checking
reservation status of complex virtual resources (stacks) by
having an opportunity to check status of all its 'nested'
components, like VMs, networks, etc. This can be done as well by
using just Heat without reservation service. Now we are thinking
about reservation as the reservation of the OpenStack resource
that has ID in the OpenStack service DB, no matter how complex it
is (VM, network, floating IP, stack, etc.)
I am not sure I am getting this...? All I wanted to say is that
orchestration is a pretty big deal and my recommendation is not to
do any of this at all in the reservation service but rely on Heat
instead when possible. I understand you seem to agree with this...
Also, I am not sure how you can do stack reservations on the basis
of a Heat template when it has auto-scaling groups.
4) We were thinking about Reservation Scheduler as a service that
controls lease life cycle (starting, ending, making user
notifications, etc.) and communicates with Reservation Manager
via RPC. Reservation Manager can send user notifications about
close lease ending using Ceilometer (this question has to be
researched). As for the time needed to run physical reservation
or complex virtual one, that is used to make preparations and
settings, I think it would be better for user to amortise it in
lease using period, because for physical resources it much
depends on hardware resources and for virtual ones - on hardware,
network and geo location of DCs.
Do you mean make the user aware of the provisioning lead time in
the lease schedule? How do suggest they know how to account for
that? In practice, a lease is a contract and so the reservations
must be available at the exact time the lease becomes effective.
Thank you,
DIna.
On Mon, Aug 5, 2013 at 1:22 PM, Julien Danjou <jul...@danjou.info
<mailto:jul...@danjou.info>> wrote:
On Fri, Aug 02 2013, Patrick Petit wrote:
> 3. The proposal specifies that a lease can contain a combo
of different
> resources types reservations (instances, volumes, hosts,
Heat
> stacks, ...) that can even be nested and that the
reservation
> service will somehow orchestrate their deployment when
the lease
> kicks in. In my opinion, many use cases (at least ours)
do not
> warrant for that level of complexity and so, if that's
something
> that is need to support your use cases, then it should
be delivered
> as module that can be loaded optionally in the system.
Our preferred
> approach is to use Heat for deployment orchestration.
I agree that this is not something Climate should be in
charge. If the
user wants to reserve a set of services and deploys them
automatically,
Climate should provide the lease and Heat the deployment
orchestration.
Also, for example, it may be good to be able to reserve
automatically
the right amount of resources needed to deploy a Heat stack
via Climate.
--
Julien Danjou
// Free Software hacker / freelance consultant
// http://julien.danjou.info
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--
Best regards,
Dina Belova
Software Engineer
Mirantis Inc.
--
Patrick Petit
Cloud Computing Principal Architect, Innovative Products
Bull, Architect of an Open World TM
Tél :+33 (0)4 76 29 70 31 <tel:%2B33%20%280%294%2076%2029%2070%2031>
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