Use Crane to push a Docker multi image to registry

push-docker-multi-image-tar.go

package main

import (
	"flag"
	"fmt"
	"io"
	"os"
	"path"

	"github.com/google/go-containerregistry/pkg/crane"
	"github.com/google/go-containerregistry/pkg/name"
	"github.com/google/go-containerregistry/pkg/v1/tarball"
)

func pathOpener(path string) tarball.Opener {
	return func() (io.ReadCloser, error) {
		return os.Open(path)
	}
}

//  docker save alpine busybox > ./images.tar 
//  <app> ./images.tar http://localhost:5000
func main() {
	manifest := flag.Bool("m", false, "Set to show manifest only")
	flag.Parse()
	args := flag.Args()
	file := args[0]
	repo := args[1]
	fmt.Println("Tarball: ", file)
	fmt.Println("Target Repo: ", repo)
	man, err := tarball.LoadManifest(pathOpener(file))
	if err != nil {
		panic(err)
	}
	if *manifest {
		for _, d := range man {
			for _, t := range d.RepoTags {
				fmt.Println(t)
			}
		}

		return
	}
	for _, d := range man {
		for _, t := range d.RepoTags {
			tag, err := name.NewTag(t)
			if err != nil {
				panic(err)
			}
			i, err := tarball.Image(pathOpener(file), &tag)
			if err != nil {
				panic(err)
			}
			target := path.Join(repo, t)
			fmt.Printf("Push %s -> %s", t, target)
			fmt.Println()
			err = crane.Push(i, target)

			if err != nil {
				panic(err)
			}
		}

	}
}