Updates for golden image heterogenous cluster support

[erpeters157]

Updates related to CNV-61640, support for golden images in heterogenous clusters.

Version(s):
4.20

Issue:
https://issues.redhat.com/browse/CNV-61640

Link to docs preview:

• Heterogeneous cluster support
  -- Enabling heterogeneous cluster support
  -- Modifying a common golden image source in a heterogeneous cluster
  -- Adding a custom golden image in a heterogeneous cluster
  -- Modifying workloads node placement in a heterogeneous cluster
• Creating a VM from a template
• Creating a VM from an instance type by using the web console
• Generalizing a VM image

QE review:

• QE has approved this change.

Additional information:

[ocpdocs-previewbot]

🤖 Tue Oct 21 19:28:22 - Prow CI generated the docs preview:
https://99811--ocpdocs-pr.netlify.app
Complete list of updated preview URLs: artifacts/updated_preview_urls.txt

[avivtur]

LGTM as for the parts referring to the web console

[nunnatsa]

Thanks @erpeters157 !

Several things I fill missing:

1. The fact that the feature is in tech-preview, and is not fully supported
2. some background: e.g. what is the problem we're trying to solve here and why is it needed; what are the risk of not solving the issue; what are multi-arch manifest images (e.g. add a link to some cncf doc) and so on.
   you can use the background part of these docs for reference:
   1. VEP
   2. Upstream user guide
3. Add an alternative to enabling the feature; see the runbook of the HCOMultiArchGoldenImagesDisabled alert

[Acedus]

So the lower-level resource that is a DataVolume, which is essentially used to power this entire feature behind the scenes, is pretty much usable out-of-the-box. With that said, aside from upstream documentation on the matter[1], there's no mention of it in the official OpenShift docs and I believe that for certain advanced users, this information may be valuable, should we include it?

[1] https://github.com/kubevirt/containerized-data-importer/blob/main/doc/image-from-registry.md#import-registry-image-by-platform-specification

[nunnatsa]

Hi @erpeters157 . Thanks for the fixes.

I still think we must have some background of why this feature is needed, and what is the risk of not using it in heterogeneous cluster. I think it's a meaningful risk and the user should know about it. This is why we added a special alert for this case.

[erpeters157]

@nunnatsa Thanks for your feedback. It's definitely still a work in progress based on everyone's feedback but I appreciate your input.

[erpeters157]

@Acedus I'm still new to CNV but I'll ask the established writers if there is a reason why this isn't mentioned in the downstream documentation. I'm going to focus on addressing what we need to document for heterogenous cluster support and if I have time, and it should be added, I will work on that. If I can't get to it, may be we could open a Jira to make it an async update.

[erpeters157]

@Acedus I spoke to my team and none of them know why the DataVolume resource does not appear in the downstream documentation. Since we are close to GA, I will create a documentation Epic in Jira to follow up on this post-GA. I will make you the reporter and assign it to myself. Thank you very much for bringing this issue to our attention.

[erpeters157]

@nunnatsa Please see my latest updates with more of the information you requested. Please let me know if this is good or you'd would like additions. Thank you for your support and feedback.

[duyanyan]

/lgtm

[danielclowers]

few things needing addressed and a couple of suggestions

[erpeters157]

@nunnatsa Please see my latest updates. I rearranged the text order in the section introduction and called out the bit about the potential problems for not using it in an IMPORTANT note. Does this work better for you?

[nunnatsa]

/lgtm

[nunnatsa]

/lgtm

[ousleyp]

there might be more things, but these are the things that jumped out at me. overall it looks great though!

[bergerhoffer]

The branch/enterprise-4.21 label has been added to this PR.

This is because your PR targets the main branch and is labeled for enterprise-4.20. And any PR going into main must also target the latest version branch (enterprise-4.21).

If the update in your PR does NOT apply to version 4.21 onward, please re-target this PR to go directly into the appropriate version branch or branches (enterprise-4.x) instead of main.

[openshift-ci]

New changes are detected. LGTM label has been removed.

[sjhala-ccs]

@erpeters157 A few more suggestions before this is ready for merging. Thanks!

[openshift-ci]

@erpeters157: all tests passed!

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[sjhala-ccs]

lgtm

[sjhala-ccs]

/cherrypick enterprise-4.20

[sjhala-ccs]

/cherrypick enterprise-4.21

[openshift-cherrypick-robot]

@sjhala-ccs: new pull request created: #100856

In response to this:

/cherrypick enterprise-4.20

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[openshift-cherrypick-robot]

@sjhala-ccs: new pull request created: #100857

In response to this:

/cherrypick enterprise-4.21

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