client-go-parse-yaml.md

Parse the kubernetes manifest in yaml or json, don't care a manifest type.

Examples:

package main

import (
	"bytes"
	"context"
	"flag"
	"io"
	"io/ioutil"
	"log"

	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/runtime/serializer/yaml"
	yamlutil "k8s.io/apimachinery/pkg/util/yaml"
	"k8s.io/client-go/dynamic"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/restmapper"
	"k8s.io/client-go/tools/clientcmd"
)

var (
	kubeconfig string
	filename   string
)

func main() {
	flag.StringVar(&kubeconfig, "kubeconfig", "", "")
	flag.StringVar(&filename, "f", "", "")
	flag.Parse()

	b, err := ioutil.ReadFile(filename)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("%q \n", string(b))

	config, err := clientcmd.BuildConfigFromFlags("", kubeconfig)
	if err != nil {
		log.Fatal(err)
	}

	c, err := kubernetes.NewForConfig(config)
	if err != nil {
		log.Fatal(err)
	}

	dd, err := dynamic.NewForConfig(config)
	if err != nil {
		log.Fatal(err)
	}

	decoder := yamlutil.NewYAMLOrJSONDecoder(bytes.NewReader(b), 100)
	for {
		var rawObj runtime.RawExtension
		if err = decoder.Decode(&rawObj); err != nil {
			break
		}

		obj, gvk, err := yaml.NewDecodingSerializer(unstructured.UnstructuredJSONScheme).Decode(rawObj.Raw, nil, nil)
		unstructuredMap, err := runtime.DefaultUnstructuredConverter.ToUnstructured(obj)
		if err != nil {
			log.Fatal(err)
		}

		unstructuredObj := &unstructured.Unstructured{Object: unstructuredMap}

		gr, err := restmapper.GetAPIGroupResources(c.Discovery())
		if err != nil {
			log.Fatal(err)
		}

		mapper := restmapper.NewDiscoveryRESTMapper(gr)
		mapping, err := mapper.RESTMapping(gvk.GroupKind(), gvk.Version)
		if err != nil {
			log.Fatal(err)
		}

		var dri dynamic.ResourceInterface
		if mapping.Scope.Name() == meta.RESTScopeNameNamespace {
			if unstructuredObj.GetNamespace() == "" {
				unstructuredObj.SetNamespace("default")
			}
			dri = dd.Resource(mapping.Resource).Namespace(unstructuredObj.GetNamespace())
		} else {
			dri = dd.Resource(mapping.Resource)
		}

		if _, err := dri.Create(context.Background(), unstructuredObj, metav1.CreateOptions{}); err != nil {
			log.Fatal(err)
		}
	}
	if err != io.EOF {
		log.Fatal("eof ", err)
	}
}

Usage:

app.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: nginx
  name: nginx
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  strategy:
    rollingUpdate:
      maxSurge: 25%
      maxUnavailable: 25%
    type: RollingUpdate
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: demo
  name: demo
  namespace: default
spec:
  ports:
  - name: web
    port: 80
  selector:
    app: demo
  type: ClusterIP

go run demo.go -kubeconfig ~/.kube/config -f app.yaml