client-go：将kubernetes json文件解析为k8s结构

Question

i would like to parse kubernetes manifest file (json/yaml) and be able to convert them to k8s structures (to later on manipulate them)

I know there is the NewYAMLOrJSONDecoder().Decode() function (https://github.com/kubernetes/apimachinery/blob/master/pkg/util/yaml/decoder.go) to read a json/yaml file, but the next step is: how to convert them to k8s structure/type?

i.e. if I read a yaml file with a Namespace object, how to convert it to a core/v1/namespace interface for example

Regards,

Answer 1

This question is very similar to How to deserialize Kubernetes YAML file, but this question is a bit outdated, since the package names changed.

Also it doesn't directly use the go client, which means there might be another solution to this.

Here is a example:

package main

import (
    "fmt"

    "k8s.io/kubernetes/pkg/api"
    _ "k8s.io/kubernetes/pkg/api/install"
    _ "k8s.io/kubernetes/pkg/apis/extensions/install"
    "k8s.io/kubernetes/pkg/apis/extensions/v1beta1"
)

var json = `
{
  "apiVersion": "extensions/v1beta1",
  "kind": "Deployment",
  "metadata": null,
  "name": "my-nginx",
  "replicas": 2,
  "spec": null,
  "template": {
    "metadata": {
      "labels": {
        "run": "my-nginx"
      }
    },
    "spec": {
      "containers": [
        {
          "image": "nginx",
          "name": "my-nginx",
          "ports": [
            {
              "containerPort": 80
            }
          ]
        }
      ]
    }
  }
}
`

func main() {
    // decode := api.Codecs.UniversalDecoder().Decode
    decode := api.Codecs.UniversalDeserializer().Decode

    obj, _, err := decode([]byte(json), nil, nil)
    if err != nil {
        fmt.Printf("%#v", err)
    }

    deployment := obj.(*v1beta1.Deployment)

    fmt.Printf("%#v
", deployment)
}

Notes

• the .../install packages are important, since they define which types can get decoded
• it's able to decode JSON, YAML and probably also all other supported file types
• not sure where the difference between UniversalDecoder and UniversalDeserializer is