support vsphere disk.enableUUID model config

[Kevin W Monroe]

Juju supports a few model config options for vsphere already ([external|primary]-network, datastore):

https://jujucharms.com/docs/2.3/help-vmware#bootstrapping

We should include disk.enableUUID in this list. Kubernetes can exploit vsphere storage features, but it requires all worker nodes to know the underlying disk uuid:

https://vmware.github.io/vsphere-storage-for-kubernetes/documentation/existing.html#step-3-enable-disk-uuid-on-node-virtual-machines

It feels like the right place to do this would be in createImportSpec so that all VMs created in a properly configured model would have it enabled:

https://github.com/juju/juju/blob/develop/provider/vsphere/internal/vsphereclient/createvm.go#L277

Users might set this like:

juju model-defaults vsphere disk-enable-uuid=1

[Kevin W Monroe (kwmonroe)]

Any news on a release target for this?

[John A Meinel (jameinel)]

AFAIK nobody is looking at this, and it is triaged at Medium so it isn't
considered a priority. If there is reason to escalate the priority please
discuss. Probably directly with Tim, rather than via just the bug
conversation.

On Wed, Apr 11, 2018 at 10:02 PM, Kevin W Monroe <<email address hidden>
> wrote:

> Any news on a release target for this?
>
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> Title:
> support vsphere disk.enableUUID model config
>
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[John A Meinel (jameinel)]

For my 2c, is there any reason *not* to always set disk.enableUUID always?
What is the reason you'd ever want disk.enableUUID to be 0 ?

On Thu, Apr 12, 2018 at 2:56 PM, John Meinel <email address hidden> wrote:

> AFAIK nobody is looking at this, and it is triaged at Medium so it isn't
> considered a priority. If there is reason to escalate the priority please
> discuss. Probably directly with Tim, rather than via just the bug
> conversation.
>
>
> On Wed, Apr 11, 2018 at 10:02 PM, Kevin W Monroe <
> <email address hidden>> wrote:
>
>> Any news on a release target for this?
>>
>> --
>> You received this bug notification because you are subscribed to juju.
>> Matching subscriptions: juju bugs
>> https://bugs.launchpad.net/bugs/1751858
>>
>> Title:
>> support vsphere disk.enableUUID model config
>>
>> To manage notifications about this bug go to:
>> https://bugs.launchpad.net/juju/+bug/1751858/+subscriptions
>>
>
>

[Kevin W Monroe (kwmonroe)]

@jam, i haven't found many use cases for wanting disk.EnableUUID to be 0. I found this:

https://blogs.vmware.com/kb/2013/03/setting-disk-enableuuidtrue-in-vmware-data-protection.html

That's pretty old, but basically, if the option was 0 (false) and an operator enabled it while the VM was running, snapshots would fail because the current config doesn't match the config from when the VM was started.

And also this:

https://kb.vmware.com/s/article/2146204

Apparently the Volume Snapshot Service (VSS) is tied to disk.EnableUUID; if you wanted a quiesced snapshot that doesn't interact with VSS, you might want to set the option to 0 (false).

The reason we want control over this setting is for persistent vsphere storage in kubernetes. You can't have it without disk.EnableUUID=true on the VMs:

https://vmware.github.io/vsphere-storage-for-kubernetes/documentation/existing.html#step-3-enable-disk-uuid-on-node-virtual-machines

So if we do end up supporting this with model config, perhaps the safe thing to do is default it to false to match current behavior, yet allow ops to turn it on when required.

[Ian Booth (wallyworld)]

I think we make the setting true by default since that's what's needed 99% of the time.

[Christian Muirhead (2-xtian)]

Talking about this with Ian, we thought we could default it to true for new controllers but for existing controllers have an upgrade step that sets it to false (since that's effectively what they have).

[Kevin W Monroe (kwmonroe)]

Confirmed this is set in 2.5-b3!

$ ./govc_darwin_amd64 vm.info -e=true juju-fac896-0
Name: juju-fac896-0
...
  ExtraConfig:
...
    disk.EnableUUID: true
...

Big Thanks!