✨ Add a flag to crd-puller to specify only the required CRDs that needs to be synced

[bnallapeta]

Summary

Provide an additional flag (--resources-to-sync) to specify which CRDs the user wants to pull.
Note: If the flag is not used or is empty, the default behavior(pull all CRDs on the cluster) is followed.

Typical usage is as shown below:

go run cmd/crd-puller/pull-crds.go --kubeconfig /home/bnr/.kube/config --resources-to-sync "pods,services,deployments"

Related issue(s)

#839

Fixes #839

[ncdc]

I think the path forward is to delete cmd/crd-puller from the repo. Thoughts @sttts @stevekuznetsov @davidfestal?

[sttts]

Would wait for the API management epic to unfold. There we need something like crdpuller.

[ncdc]

Sorry for taking so long on this one - are you still interested in getting this merged? If you can make these changes, we can get it in! Thanks!

[bnallapeta]

@ncdc PTAL. I have worked on all the changes.
I had to introduce a third variable in order to handle the case where the user does not pass any value. I wasn't able to do this with just one var of type string or []string.

[ncdc]

These diffs should make it work without the need for an extra variable

[ncdc]

/test all

[bnallapeta]

@ncdc Done. PTAL.

[openshift-ci]

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This pull-request has been approved by: ncdc

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[ncdc]

/test all

[ncdc]

Fixed the imports

[ncdc]

/lgtm

[ncdc]

Going to close and reopen to get Prow to do all the tests

[ncdc]

/test all

[ncdc]

kcp-dev/contrib-tmc#93
/test test