main.go

package main

import (
	"errors"
	"fmt"
	"io"
	"os"

	"github.com/google/go-containerregistry/pkg/authn"
	"github.com/google/go-containerregistry/pkg/name"
	v1 "github.com/google/go-containerregistry/pkg/v1"
	"github.com/google/go-containerregistry/pkg/v1/mutate"
	"github.com/google/go-containerregistry/pkg/v1/remote"
)

func main() {
	if len(os.Args) != 2 {
		fmt.Println("usage: tmp image")
		os.Exit(1)
	}

	image := os.Args[1]

	ref, err := name.ParseReference(image)
	if err != nil {
		fmt.Println("Cannot parse image name %s: ", image, err)
		os.Exit(1)
	}

	auth := remote.WithAuthFromKeychain(authn.DefaultKeychain)

	desc, err := remote.Get(ref, auth)
	if err != nil {
		fmt.Println("Cannot access remote index: ", err)
		os.Exit(1)
	}

	idx, err := desc.ImageIndex()
	if err != nil {
		fmt.Println("This program expects an index not a plain image, sorry: ", err)
		os.Exit(1)
	}

	annotations := map[string]string{"test": "value"}

	newIdx := mutate.Annotations(idx, annotations).(v1.ImageIndex)

	ch := make(chan v1.Update, 100)
	go func() {
		_ = remote.WriteIndex(ref, newIdx, auth, remote.WithProgress(ch))
	}()
	for update := range ch {
		switch {
		case update.Error != nil && errors.Is(update.Error, io.EOF):
			fmt.Fprintf(os.Stderr, "receive error message: %v\n", err)
			fmt.Printf("%d/%d", update.Complete, update.Total)
			break
		case update.Error != nil:
			fmt.Printf("error writing tarball: %v\n", update.Error)
			os.Exit(1)
		default:
			fmt.Fprintf(os.Stderr, "receive update: %#v\n", update)
		}
	}
}