[RFE / vsphere provider] expose "ESXi Compatiblity" as a constraint when creating VMs

[Pedro Guimarães]

Hi,

Today, we cannot set on vsphere provider which ESXi Compatibility (Hardware Version) am I willing to use. I may need more recent HW versions for things like newer vsphere - kubernetes integration features (LP #1851215 and ref [1]).

Ideally, I should be able to configure this per-machine, therefore I consider "constraints" as the best place to add this new feature. Discussing this with @2-xtian, he suggested that we adopt "virt-type" constraint to vsphere and use it to map HW Version.

We always should be mindful of issues such as LP #1851676, though.

[1] https://cloud-provider-vsphere.sigs.k8s.io/tutorials/kubernetes-on-vsphere-with-kubeadm.html

[John A Meinel (jameinel)]

We could certainly add this knob. When we tried to just move to a newer Hardware Compatibility in the past, we couldn't get the Ubuntu VMA to boot, because it had kernel issues during boot.
There is also the question of "on this version of VSphere with this Ubuntu Image, what is the best HC version to use", which is very hard for Juju to answer without a lot of feedback. We could expose it as some sort of constraints/model-config. Though model-config is a bit too coarse, and constraints are generally provider agnostic.