Support generating reference resolvers targeting multiple types

[wwentland]

What problem are you facing?

It is currently not possible to generate ResolveReferences methods that target multiple suitable types even though there are cases in which this would be desirable.

A good example for this are references to KMS CMKs and Aliases in AWS.

Either can be used as reference in a SQS Queue's kmsMasterKeyId and Crossplane should support both.

How could Crossplane help solve your problem?

Resolving of references to KMS Keys for Queues has been implemented in the following way:

// KMSMasterKeyID - The ID of an AWS-managed customer master key (CMK)
// ...
// +crossplane:generate:reference:type=github.com/crossplane/provider-aws/apis/kms/v1alpha1.Key
KMSMasterKeyID *string `json:"kmsMasterKeyId,omitempty"`
KMSMasterKeyIDRef *xpv1.Reference `json:"kmsMasterKeyIdRef,omitempty"`
KMSMasterKeyIDSelector *xpv1.Selector `json:"kmsMasterKeyIdSelector,omitempty"`

It would be absolutely fantastic if crossplane-tools would support listing multiple suitable types here, similar to:

// KMSMasterKeyID - The ID of an AWS-managed customer master key (CMK)
// ...
// +crossplane:generate:reference:type=github.com/crossplane/provider-aws/apis/kms/v1alpha1.Key
// +crossplane:generate:reference:type=github.com/crossplane/provider-aws/apis/kms/v1alpha1.Alias
KMSMasterKeyID *string `json:"kmsMasterKeyId,omitempty"`
KMSMasterKeyIDRef *xpv1.Reference `json:"kmsMasterKeyIdRef,omitempty"`
KMSMasterKeyIDSelector *xpv1.Selector `json:"kmsMasterKeyIdSelector,omitempty"`

If there are multiple suitable candidates users would use matchLabels and suitable matches to differentiate between these resources.

Thank you!

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[wwentland]

This would still be great to have.

[mbbush]

I would love to have this too

[selfuryon]

Really needed functionality