YAML Unmarshal changes keys

[vika...@gmail.com]

I am new to GoLang and looking to join two keys (rules) from two different Yamls.

I have been able to join the keys but I found that Unmarshal changes the keys (example apiVersion to APIVersion, and kind to Kind).

Overall, my goal is to have a valid Kubernetes YAML manifest. This is what I have attempted so far https://goplay.tools/snippet/zWYDjnTeA0Q 

## 

package main

import (

"fmt"

"github.com/InVisionApp/conjungo"

"github.com/ghodss/yaml"

)

type ClusterRole struct {

APIVersion string `yaml:"apiVersion"`

Kind string `yaml:"kind"`

Metadata struct {

Name string `yaml:"name"`

} `yaml:"metadata"`

Rules []struct {

APIGroups []string `yaml:"apiGroups"`

Resources []string `yaml:"resources"`

Verbs []string `yaml:"verbs"`

} `yaml:"rules"`

}

func main() {

yaml1 := `

---

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: role1

rules:

- apiGroups:

- ""

resources:

- services

verbs:

- create

- delete

- apiGroups:

- apiregistration.k8s.io

resources:

- apiservices

verbs:

- create

- delete

`

yaml2 := `

---

apiVersion: rbac.authorization.k8s.io/v1

kind: ClusterRole

metadata:

name: role2

rules:

- apiGroups:

- ""

resources:

- secrets

- events.k8s.io

verbs:

- list

- watch

- apiGroups:

- metrics.k8s.io

resources:

- nodes

- bindings

verbs:

- get

`

var role1 ClusterRole

yaml.Unmarshal([]byte(yaml1), &role1)

fmt.Printf("\n## ROLE1\n %v", role1)

var role2 ClusterRole

yaml.Unmarshal([]byte(yaml2), &role2)

fmt.Printf("\n\n## ROLE2\n %v", role2)

conjungo.Merge(&role1, role2, nil)

// Struct to Marshal

y, err := yaml.Marshal(role1)

if err != nil {

fmt.Printf("\nerr: %v\n", err)

return

}

fmt.Printf("\n\n## MERGED ROLE\n %v", string(y))

}

[Sam Hughes]

I skipped over to that package, and the doc says it converts from yaml to json, and the marshals/unmarshals. I tried changing your snippet to use struct tags with the key name as "json" instead of "yaml", and it immediately behaved as expected: https://goplay.tools/snippet/PSZtr1YErD8

While you're fine to use it like you are, the package you're using is a wrapper around another tool, pkg.go.dev/gopkg.in/yaml.v2, using that tool to convert to/from json, and then using encode/json to marshal/unmarshal. The benefit would be using common marshal/unmarshal handlers and one set of struct tags. Meanwhile, you're not interacting with both yaml and json, so I suggest actually changing the tool you're using to support yaml directly.

1. Simple fix: replace `yaml:"<fieldname>"` with `json:"<fieldname>"`

2. Better fix that might break some code: use gopkg.in/yaml.v2 instead of github.com/ghodss/yaml, to avoid unexpected behavior, such as what you observed.

[vika...@gmail.com]

Thanks a ton for the explanation and for helping to fix the issue. I will keep the yaml library in mind.