Kubernetes go-client deployment patching.

main.go

package main

// the equivalent of kubectl set image deployment/api api="image"

import (
	"fmt"
	patchtype "k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/kubernetes"
	_ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/clientcmd"
	"os"
	"path/filepath"
	"reflect"
)

func homeDir() string {
	if h := os.Getenv("HOME"); h != "" {
		return h
	}
	return os.Getenv("USERPROFILE") // windows
}

func context(context string) (*rest.Config, error) {
	home := homeDir()
	kubeconfig := filepath.Join(home, ".kube", "config")
	return clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
		&clientcmd.ClientConfigLoadingRules{ExplicitPath: kubeconfig},
		&clientcmd.ConfigOverrides{
			CurrentContext: context,
		}).ClientConfig()
}

func main() {
	// switch context
	config, err := context("cluster-name")
	if err != nil {
		panic(err.Error())
	}

	// create the clientset
	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}

	const patchjson = `{
	  "spec": {
	    "template": {
	      "spec": {
	        "containers": [
	          { "name": "app", "image": "<image name>" }
	        ]
	      }
	    }
	  }
	}
	`
	deployment, err := clientset.AppsV1beta1().Deployments("default").Patch(
		"app",
		patchtype.StrategicMergePatchType,
		[]byte(patchjson))

	fmt.Println(deployment)
	fmt.Println(err)

}