Fixes bazel build system for those using bazelisk

[bc185174]

What this PR does / why we need it:

• Adds .bazelversion to ensure we have a good version of bazel chosen when building the repo. Users with bazel > 5.4.1 will hit build errors or those on 7.x.x will attempt to enable bazel modules.
• Adds standard .user.bazelrc and .ci.bazelrc options for users to configured.
• Adds bazel dirs to .gitignore so they are not checked into git.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

N/A

Special notes for your reviewer:

Bazel is built with reproducibility in mind. Library, test, and binary builds are incremental, so there is not really any need to rely on external build containers since the binaries should always produce the same result.

I know its not always possible but should try to avoid cgo. These types of builds are complicated and often you'll hit build issues and break cross compiling. Not to mention its slower. Couple good article reads below on these topics but generally if you can avoid it, don't use it or at a last resort isolate the cgo dependencies.

https://dave.cheney.net/2016/01/18/cgo-is-not-go
https://relistan.com/cgo-when-and-when-not-to-use-it

Release note:

NONE

[kubevirt-bot]

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[kubevirt-bot]

Hi @bc185174. Thanks for your PR.

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[mhenriks]

/ok-to-test

[mhenriks]

/test all

[mhenriks]

@bc185174 can you explain how your comments on reproducibility and cgo are relevant here?

[bc185174]

@bc185174 can you explain how your comments on reproducibility and cgo are relevant here?

Yeah sure. They're not really relevant to this PRs fix but just a general observation when I was trying to run tests/build binaries locally. I didn't realise you had build containers to test in! I think the build container is great for workflows, but devs shouldn't need this to run and build things locally.

• Ensure users are using a good version of bazel for the repo (bazelisk is amazing for this).
• bazel run //:gazelle shouldn't produce a diff.
• bazel build //... should not produce build errors.

Must admit I'm not up to scratch with why you use cgo as there are good reasons to! But there are pretty decent go libraries out there now trying to replace the need for calling C libraries and removing that dependency. See you use cgo for libguestfs.org/libnbd - https://github.com/pojntfx/go-nbd for example.

Side-note: k8s sig recommends against their fake client now with preference of using envtest as you are using a real client and a real API server.

[akalenyu]

Side-note: k8s sig recommends against their fake client now with preference of using envtest as you are using a real client and a real API server.

Would you mind linking the source? sounds really interesting

[bc185174]

Side-note: k8s sig recommends against their fake client now with preference of using envtest as you are using a real client and a real API server.

Would you mind linking the source? sounds really interesting

Sure https://pkg.go.dev/sigs.k8s.io/controller-runtime/pkg/client/fake#pkg-overview. Kube-builder have quite a useful reference as well https://book.kubebuilder.io/reference/envtest.html.

[kubevirt-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
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/lifecycle stale

[awels]

/remove-lifecycle stale
Just checking in with @akalenyu and @mhenriks to see what is missing here to get this over the finish line. Its been in here for a while.

[kubevirt-bot]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

/lifecycle stale

[kubevirt-bot]

Stale issues rot after 30d of inactivity.
Mark the issue as fresh with /remove-lifecycle rotten.
Rotten issues close after an additional 30d of inactivity.

If this issue is safe to close now please do so with /close.

/lifecycle rotten