Conversion function is registered to copy of scheme

[lubronzhan]

What steps did you take and what happened?

Similar to vmware-tanzu/vm-operator#1132

One of the example here

localSchemeBuilder = schemeBuilder

localSchemeBuilder is a copy, not a pointer to schemeBuilder.

While code here registers the func to the copy.

localSchemeBuilder.Register(RegisterConversions)

So the conversion functions in RegisterConversions are not actually registered.

Server-side (apiserver) conversion webhook use Hub/Spoke pattern which delegates to Convert_* functions, but they do not use the scheme’s RegisterConversions automatically. So server side conversion doesn't get impacted, so this bug was never discovered.
This happens when someone tries to explicitly call the scheme.Convert() from client.

What did you expect to happen?

localSchemeBuilder = &schemeBuilder

A simple replaceAll should do the work

Cluster API version

All

Kubernetes version

No response

Anything else you would like to add?

No response

Label(s) to be applied

/kind bug
One or more /area label. See https://github.com/kubernetes-sigs/cluster-api/labels?q=area for the list of labels.

[k8s-ci-robot]

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Details

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[sbueringer]

cc @camilamacedo86 (in case that affects kubebuilder as well)

Thx for reporting!

[camilamacedo86]

Thank you for ping me out.
There we use schemeBuilder only so I think we are not affected.

[sbueringer]

Interesting. What is the generated conversion code using? The only reason we have localSchemeBuilder is because the generated conversion code is using it

[sbueringer]

See:

cluster-api/api/addons/v1beta1/zz_generated.conversion.go

Line 35 in 5cfc702

localSchemeBuilder.Register(RegisterConversions)

[lubronzhan]

See:

cluster-api/api/addons/v1beta1/zz_generated.conversion.go

Line 35 in 5cfc702

localSchemeBuilder.Register(RegisterConversions)

The server-side webhook won't be impacted, just when you tries to use scheme.Convert on the client then it will happen. So it was never caught