main.go

package main

import (
	"flag"
	"fmt"
	"log"
	"strings"

	"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/empty"
	"github.com/google/go-containerregistry/pkg/v1/mutate"
	"github.com/google/go-containerregistry/pkg/v1/remote"
	"github.com/google/go-containerregistry/pkg/v1/tarball"
	"github.com/google/go-containerregistry/pkg/v1/types"
)

var refstr = flag.String("ref", "", "Reference to push manifest list to")

func main() {
	flag.Parse()

	ref, err := name.ParseReference(*refstr)
	if err != nil {
		log.Fatalf("name.ParseReference: %v", err)
	}

	// GCR doesn't allow an image with no layers, so let's create an image
	// with one empty layer.
	l, err := tarball.LayerFromReader(strings.NewReader(""))
	if err != nil {
		log.Fatalf("tarball.LayerFromReader: %v", err)
	}
	img, err := mutate.AppendLayers(empty.Image, l)
	if err != nil {
		log.Fatalf("mutate.AppendLayers: %v", err)
	}

	var idx v1.ImageIndex = empty.Index
	for _, p := range []v1.Platform{{
		OS:           "linux",
		Architecture: "amd64",
	}, {
		OS:           "windows",
		Architecture: "amd64",
	}} {
		idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
			Add: img,
			Descriptor: v1.Descriptor{
				MediaType: types.OCIManifestSchema1,
				Platform:  p.DeepCopy(),
			},
		})
	}

	if err := remote.WriteIndex(ref, idx, remote.WithAuthFromKeychain(authn.DefaultKeychain)); err != nil {
		log.Fatalf("remote.WriteIndex: %v", err)
	}
	d, err := idx.Digest()
	if err != nil {
		log.Fatalf("index.Digest: %v", err)
	}
	fmt.Println(ref.Context().Digest(d.String()))
}