[pve-devel] training week: students feedback/requests

[aderumier at odiso.com]

Le vendredi 04 juin 2021 à 09:52 +0200, Thomas Lamprecht a écrit :
> Hi,
> 
> On 04.06.21 05:21, aderumier at odiso.com wrote:
> > Hi,
> > I just finish the last training week session,
> > here some students feedback/requesst:
> 
> thanks for your feedback!
> > - add support for vm offlline vm migration with local usb or pci
> > devices.
> >   1 student have same special device on multiple hosts, and want to
> > be
> > able to offline move vm when it need to do maintenance.
> >   It's currently possible with HA anyway.
> 
> Sounds reasonable, IIRC, allowing it in HA was a result from some bug
> entry
> where user had also identical GPUs reserved for the recovery case.
yes, I think currently we don't have any check to not allowing same
device sharing across 
multiple vms ? Ha is pretty dump too, try to start vm if host don't
have device/storage/network. (I would like to improve that in the
future, but I don't have enough time ;)

> 
> > - allow vm migration with local storage cloud-init drive.
> >   Without need to replicate it, I think it could be pretty easy to
> > regenerate cloud-init drive on target host if same local storage
> > name
> > exist on target.
> 
> Yeah, sync or regeneration should both work from PVE side, wolfgang
> had
> some objections for the regeneration of CI drives, it could be a bit
> unexpected for a guest process having that open, IMO they should just
> handle
> that. Do you have any experience of issues with regeneration in
> practice?
> 
It's really not a problem. I have done a lot of try with regenerate the
config drive online. (I'm currently still working to improve cloudinit
onlines changes)
and with a different content, even with unplug/replug the config drive
with the iso mounted,
it's working without any problem.
And even if a file is currently read, it's open as read only. so you
can remount to a different iso without any lock.
So here, with a live migration, with same content regenerated, I really
don't see any problem.
The cloud-init don't keep any file open after reading them, I don't
think the iso is even mounted after cloudinit has runned.



> > 
> > - allow vm online vm migration for specific usb devices.
> >   Maybe a little bit more complex, user have special usb devices
> > (googl
> > coral usb tensorflow accelerator) on multiple host.
> >   I think it could be possible to unplug device before migration,
> > and
> > rattach it afte migration.  (The application running inside th vm
> > is
> > able to handle this).
> >   So maybe adding an option on usb device like "allow migrate"
> > could be
> > enough ?
> 
> funnily we'd have a use case for that too (some HSM). It'd like to
> see
> some USB plug improvements in general anyway, i.e., allowing one to
> add
> new USB hubs so that the rather low current limit could be exceeded.

I already have some students requests about security/license dongle for
example.

> 
> This and the PCI one would need some extra checking on the target
> node,
> i.e., some basic "all local HW the VM config refers too present?" to
> make
> it a bit nicer.
> 
yes , agreed.

> > 
> > - be able to move vms from a dead node.
> >   Currently the only was is to move manually the vms config files.
> >   Maybe adding a special wizard, only for root, with a lot of
> > warning,
> > could be great. 
> > 
> 
> Can be pretty dangerous, but I do not really want to object that
> completely,
> in the end the Admin needs to be the one knowing if it is safe, and
> we
> want to reduce the steps where one needs to switch to the CLI, so
> yeah,
> we could add this with great care about how to present this somewhat
> safely.
> 
yes, pretty dangerous. That's why I was thinking of a special wizard
somewhere  with a lot of warning, not just "click on vm of the dead
node-> move")
or maybe cli only.
Move files manually is pretty bad too currently, as you don't have any
check if the storage exist for example

> > 
> > - Backups: add some kind of lock/queues when you are doing a single
> > schedule of "vzdump -all .."
> > Currently, it's launch vzdump on all nodes at the same time. 
> > If user have a lot of nodes, it can easily flood the backup
> > storage, or
> > backup storage network.
> > it could be great to be able to define something like: "the backup
> > storage is able to handle X backups jobs in parallel"
> > 
> 
> Would need some thoughts about how to implement this fitting good in
> the
> existing stack, but yes, we heard that one a few times already, and
> seems
> definetively like a sensible request.
> 
> > 
> > - vm start order: be able to add vms dependencies, 
> >                   like a vm2 need to wait that vm1 is started (and
> > if
> > guest agent is used, wait that agent is running, to be sure that
> > vm1 is
> > fully booted)
> 
> Hmm, how do you check the "fully" booted case though? 
I was thinking to simply check if the agent is running. (not perfect,
but still an improvement)

> Also, wait for ever
> if the dependent VM is on another node which is currently offline?
maybe add a timeout if the depend vm is not started
> 
> A manual start would probably need to allow overriding such ordering
> too,
> I guess.
> 
yes indeed.
(This request is really not a big priority for the student)


> > 
> > 
> > Gui:
> > 
> > - Displaying nodes versions in the datacenter sumarry node list.
> 
> sounds sensible, I'd like to have a panel there with update/repo
> status
> of all nodes anyway, to have a more central view about pending or
> not-configured updates.
> 
yes, student request was to have something central to display current
versions,
and even better pending update

> > - In vms notes: if user add an http://... link, display it as link
> > to
> > be clickable
> 
> I checked out a few small markdown JS libraries in the pase, as that
> was
> also requested at least once, but just doing simple link https?
> detection
> and wrapping them in <a> tags could be enough for most as a starter.
yes, something like that.  not a big priority request too.

> 
> > 
> > - add saml authentification 
> > 
> 
> You may have seen that there's some effort going on in that space
> thanks to
> Julien BLAIS, the biggest (or basically single) blocker is which SAML
> lib.
> to use, the pure perl thing uses the perl MOOSE framework which is
> huge and
> IIRC incompatible with the lib-anyevent we use, the rust versions
> seem not
> really active, having a rust one, in combination with perlmod to
> create perl
> bindings would be great, as then all products could use the same
> base.
> 
> cheers,
> Thomas
>