Make Extra Resources convertable to json and yaml

[avarei]

What problem are you facing?

Currently extra resources have a few problems that make them more difficult to work with for composition functions which convert the RunFunctionRequest into Yaml.

I ran into this issue in function-pkl and I also saw that function-go-templating had to implement a workaround.
In both Projects we re-implement the struct to be able to convert it to and from yaml.

function-go-templating's workaround

function-pkl's workaround

How could Crossplane help solve your problem?

I currently see two potential ways this could be solved

Option 1 (Breaking)

1. add camelCased json tags to Requirements and sub structs
2. allow for both match_name and match_labels to be ANDed similar to K8s LabelSelector.

This would make them possible to be represented in yaml.

It would be breaking though.
However I think currently most composition functions have not yet implemented this. So this would hopefully not affect most users.

Option 2 (Non breaking (i think))

implement custom methods for Marshalling und Unmarshalling

• MarshalJSON
• UnmarshalJSON
• MarshalYAML
• UnmarshalYAML

A non-breaking option could be to provide a Another option could be to provide

[negz]

@avarei Could you elaborate a little bit more on what the problems are? It's not immediately obvious to me from skimming the linked workarounds.

Is it just that the protobufs are producing snake_case rather than camelCase field names when converted to YAML?

[avarei]

Hey @negz I just rediscovered this issue :)

The Problem is that when trying to represent a RunFunctionResponse in Yaml and Unmarshalling it it is currently unable to Unmarshal the Match Field of the ResourceSelector Struct.
so a ResourceSelector yaml like:

apiVersion: v1
kind: Namespace
matchName: foo

is converted into:

current := &fnv1.ResourceSelector{
    ApiVersion: "v1",
    Kind: "Namespace",
/*
    // This is missing:
    Match: &fnv1.ResourceSelector_MatchName{
        MatchName: "foo",
    },
*/
}

the same happens when using

match_name: foo
# or
match:
  matchName: foo

and this also applies to MatchLabels.

[avarei]

after some further tinkering I noticed that google.golang.org/protobuf/encoding/protojson.Unmarshal is able to correctly decode what k8s.io/apimachinery/pkg/util/yaml.Decode cannot in this case.