Open Stack

On Tue, 2021-06-15 at 15:18 +0100, Stephen Finucane wrote:
> On Thu, 2021-06-10 at 17:21 +0200, levonmelikbekjan at yahoo.de wrote:
> > Hi Stephen,
> > 
> > I'm  trying to customize my nova scheduler. However, if I change the
> > nova.conf as it is written here  
> > https://docs.openstack.org/operations-guide/de/ops-customize-compute.html
> > , then my python file cannot be found. How can I configure it
> > correctly? 
> > 
> > Do you have any idea?
> > 
> > My controller node is running with CENTOS 7. I couldn't install
> > devstack because it is only supported for CENTOS 8 version.
> 
> That document is very old. You want [1], which documents how to do this
> properly.

wwell that depend if they acatully want to write ther own filter yes
but if they want to replace the scheduler with a new one we recently
removed support for that right.
previously we had several schduler implemtation like the caching
scheduler and that old doc
https://docs.openstack.org/operations-guide/de/ops-customize-compute.html

descibes on how to replace the filter scheduler dirver with an new one.
we deprecated it ussuri
https://github.com/openstack/nova/commit/6a4cb24d39623930fd240e67d65013803459839d

and you finally removed the extention point in febuary
https://github.com/openstack/nova/commit/5aeb3a387494c4559d183d1290db3c92a96dfb90
so from wallaby on you can nolonger write an alternitvie schduler
implemenation out of tree without reverting that.

so yes
https://docs.openstack.org/nova/latest/user/filter-scheduler#writing-your-own-filter
is how you customise schduling now but you cant customise the schduler
itself out fo tree anymore.

> 
> Hope this helps,
> Stephen
> 
> [1] 
> https://docs.openstack.org/nova/latest/user/filter-scheduler#writing-your-own-filter
> 
> > Best regards
> > Levon
> > 
> > -----Ursprüngliche Nachricht-----
> > Von: Stephen Finucane <stephenfin at redhat.com> 
> > Gesendet: Montag, 31. Mai 2021 18:21
> > An: levonmelikbekjan at yahoo.de; openstack at lists.openstack.org
> > Betreff: Re: AW: Customization of nova-scheduler
> > 
> > On Mon, 2021-05-31 at 13:44 +0200, levonmelikbekjan at yahoo.de wrote:
> > > Hello Stephen,
> > > 
> > > I am a student from Germany who is currently working on his
> > > bachelor thesis. My job is to build a cloud solution for my
> > > university with Openstack. The functionality should include the
> > > prioritization of users. So that you can imagine exactly how the
> > > whole thing should work, I would like to give you an example.
> > > 
> > > Two cases should be solved!
> > > 
> > > Case 1: A user A with a low priority uses a VM from Openstack with
> > > half performance of the available host. Then user B comes in with a
> > > high priority and needs the full performance of the host for his
> > > VM. When creating the VM of user B, the VM of user A should be
> > > deleted because there is not enough compute power for user B. The
> > > VM of user B is successfully created.
> > > 
> > > Case 2: A user A with a low priority uses a VM with half the
> > > performance of the available host, then user B comes in with a high
> > > priority and needs half of the performance of the host for his VM.
> > > When creating the VM of user B, user A should not be deleted, since
> > > enough computing power is available for both users.
> > > 
> > > These cases should work for unlimited users. In order to optimize
> > > the whole thing, I would like to write a function that precisely
> > > calculates all performance components to determine whether enough
> > > resources are available for the VM of the high priority user.
> > 
> > What you're describing is commonly referred to as "preemptible" or
> > "spot"
> > instances. This topic has a long, complicated history in nova and has
> > yet to be implemented. Searching for "preemptible instances
> > openstack" should yield you lots of discussion on the topic along
> > with a few proof-of-concept approaches using external services or
> > out-of-tree modifications to nova.
> > 
> > > I’m new to Openstack, but I’ve already implemented cloud projects
> > > with Microsoft Azure and have solid programming skills. Can you
> > > give me a hint where and how I can start?
> > 
> > As hinted above, this is likely to be a very difficult project given
> > the fraught history of the idea. I don't want to dissuade you from
> > this work but you should be aware of what you're getting into from
> > the start. If you're serious about pursuing this, I suggest you first
> > do some research on prior art. As noted above, there is lots of
> > information on the internet about this. With this research done,
> > you'll need to decide whether this is something you want to approach
> > within nova itself, via out-of-tree extensions or via a third party
> > project. If you're opting for integration with nova, then you'll need
> > to think long and hard about how you would design such a system and
> > start working on a spec (a design document) outlining your proposed
> > solution. Details on how to write a spec are discussed at [1]. The
> > only extension points nova offers today are scheduler filters and
> > weighers so your options for an out-of-tree extension approach will
> > be limited. A third party project will arguably be the easiest
> > approach but you will be restricted to talking to nova's REST APIs
> > which may limit the design somewhat. This Blazar spec [2] could give
> > you some ideas on this approach (assuming it was never actually
> > implemented, though it may well have been).
> > 
> > > My university gave me three compute hosts and one control host to
> > > implement this solution for the bachelor thesis. I’m currently
> > > setting up Openstack and all the services on the control host all
> > > by myself to understand all the functionality (sorry for not using
> > > Packstack) 😉. All my hosts have CentOS 7 and the minimum
> > > deployment which I configure is Train.
> > > 
> > > My idea is to work with nova schedulers, because they seem to be
> > > interesting for my case. I've found a whole infrastructure
> > > description of the provisioning of an instance in Openstack 
> > > https://docs.openstack.org/operations-guide/de/_images/provision-an-instance.png
> > > . 
> > > 
> > > The nova scheduler 
> > > https://docs.openstack.org/operations-guide/ops-customize-compute.html
> > >  is the first component, where it is possible to implement
> > > functions via Python and the Compute API 
> > > https://docs.openstack.org/api-ref/compute/?expanded=show-details-of-specific-api-version-detail,list-servers-detail
> > >  to check for active VMs and probably delete them if needed before
> > > a successful request for an instantiation can be made. 
> > > 
> > > What do you guys think about it? Does it seem like a good starting
> > > point for you or is it the wrong approach? 
> > 
> > This could potentially work, but I suspect there will be serious
> > performance implications with this, particularly at scale. Scheduler
> > filters are historically used for simple things like "find me a group
> > of hosts that have this metadata attribute I set on my image". Making
> > API calls sounds like something that would take significant time and
> > therefore slow down the schedule process. You'd also have to decide
> > what your heuristic for deciding which VM(s) to delete would be,
> > since there's nothing obvious in nova that you could use.
> > You could use something as simple as filter extra specs or something
> > as complicated as an external service.
> > 
> > This should be lots to get you started. Once again, do make sure
> > you're aware of what you're getting yourself into before you start.
> > This could get complicated very quickly :)
> > 
> > Cheers,
> > Stephen
> > 
> > > I'm very happy to have found you!!! 
> > > 
> > > Thank you really much for your time!
> > 
> > 
> > [1] https://specs.openstack.org/openstack/nova-specs/readme.html
> > [2] 
> > https://specs.openstack.org/openstack/blazar-specs/specs/ussuri/blazar-preemptible-instances.html
> > 
> > > Best regards
> > > Levon
> > > 
> > > -----Ursprüngliche Nachricht-----
> > > Von: Stephen Finucane <stephenfin at redhat.com>
> > > Gesendet: Montag, 31. Mai 2021 12:34
> > > An: Levon Melikbekjan <levonmelikbekjan at yahoo.de>; 
> > > openstack at lists.openstack.org
> > > Betreff: Re: Customization of nova-scheduler
> > > 
> > > On Wed, 2021-05-26 at 22:46 +0200, Levon Melikbekjan wrote:
> > > > Hello Openstack team,
> > > > 
> > > > is it possible to customize the nova-scheduler via Python? If
> > > > yes, how? 
> > > 
> > > Yes, you can provide your own filters and weighers. This is
> > > documented at [1].
> > > 
> > > Hope this helps,
> > > Stephen
> > > 
> > > [1] 
> > > https://docs.openstack.org/nova/latest/user/filter-scheduler#writing-y
> > > our-own-filter
> > > 
> > > > 
> > > > Best regards
> > > > Levon
> > > > 
> > > 
> > > 
> > 
> > 
> 
> 
>