Strict unmarshalling should be case-sensitive

[martina-if]

Using yaml.UnmarshalStrict(...) compares keys in a case insensitive way.

I would expect it to do case sensitive comparisons of key names so that if I define a key in my schema called somethingGreat, a key in a yaml file called somethingGREat wouldn't match, and the unmarshal would fail with the error unknown field "somethingGREat".

[errordeveloper]

cc @dims @sttts @neolit123

[neolit123]

i will verify this locally.
seems like something we want to fix.

[neolit123]

/kind bug
/priority important-longterm

[dims]

/assign @neolit123

[martina-if]

How to reproduce it:

import (
	"fmt"
	// yaml "gopkg.in/yaml.v2"
	yaml "sigs.k8s.io/yaml"
)

func main() {

	type T struct {
		SomethingGreat int `yaml:"SomethingGreat,omitempty"`
	}
	var t T

	// Correct letter case
	if err := yaml.UnmarshalStrict([]byte("SomethingGreat: 1"), &t); err != nil {
		fmt.Printf("ERROR: %v\n", err)
	} else {
		fmt.Printf("Correctly parsed: %+v\n", t)
	}

	// Incorrect letter case
	if err := yaml.UnmarshalStrict([]byte("SomethingGREat: 2"), &t); err != nil {
		fmt.Printf("ERROR: %v\n", err)
	} else {
		fmt.Printf("Correctly parsed: %+v\n", t)
	}
}

Produces:

Correctly parsed: {SomethingGreat:1}
Correctly parsed: {SomethingGreat:2}

[errordeveloper]

So with yaml "gopkg.in/yaml.v2" it does actually fail:

Correctly parsed: {SomethingGreat:1}
ERROR: yaml: unmarshal errors:
  line 1: field SomethingGREat not found in type main.T

I wonder what is going on here...

[neolit123]

@martina-if @errordeveloper
see this PR in flight:
#19

Correctly parsed: {SomethingGreat:1}
ERROR: main.T.ReadObject: found unknown field: SomethingGREat, error found in #1
0 byte of ...|hingGREat":2}|..., bigger context ...|{"SomethingGREat":2}|...

[martina-if]

Hi @neolit123, thanks for the link to the PR! Do you need a review from our side?

[neolit123]

sure, go ahead.

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[neolit123]

we faced this recently again here:
kubernetes/kubeadm#2167