repo.me/x/t1/main.go

// https://iximiuz.com/en/posts/working-with-container-images-in-go/
// package main
//
// import (
//
//	"context"
//	"nf-repo/internal/util/tools"
//	"os"
//
//	"github.com/containers/image/copy"
//	"github.com/containers/image/signature"
//	"github.com/containers/image/storage"
//	"github.com/containers/image/transports/alltransports"
//	"github.com/containers/image/types"
//
// )
//
//	func main() {
//		imageName := "docker://alpine:latest"
//		srcRef, _ := alltransports.ParseImageName(imageName)
//
//		// Carries various default locations.
//		systemCtx := &types.SystemContext{}
//		policy, _ := signature.DefaultPolicy(systemCtx)
//		policyCtx, _ := signature.NewPolicyContext(policy)
//
//		dstName := imageName
//		if srcRef.DockerReference() != nil {
//			dstName = srcRef.DockerReference().String()
//		}
//		store := createStore() // see previous section
//		dstRef, _ := storage.Transport.ParseStoreReference(store, dstName)
//
//		copyOptions := &copy.Options{ReportWriter: os.Stdout}
//		manifest, _ := copy.Image(
//			context.Background(),
//			policyCtx,
//			dstRef,
//			srcRef,
//			copyOptions,
//		)
//		println(string(manifest))
//	}

package main

import (
	"encoding/json"
	"github.com/containers/image/v5/pkg/blobinfocache"
	"github.com/containers/image/v5/transports/alltransports"
	"github.com/containers/image/v5/types"
	digest "github.com/opencontainers/go-digest"
	"log"
	"nf-repo/internal/util/tools"
	"runtime"
)

type M struct {
	Manifests []struct {
		Digest    string `json:"digest"`
		MediaType string `json:"mediaType"`
		Platform  struct {
			Architecture string `json:"architecture"`
			Os           string `json:"os"`
			Variant      string `json:"variant,omitempty"`
		} `json:"platform"`
		Size int `json:"size"`
	} `json:"manifests"`
	MediaType     string `json:"mediaType"`
	SchemaVersion int    `json:"schemaVersion"`
}

func main() {
	imageName := "docker://alpine:latest"
	srcRef, _ := alltransports.ParseImageName(imageName)

	// Carries various default locations.
	systemCtx := &types.SystemContext{
		DockerInsecureSkipTLSVerify: types.OptionalBoolTrue,
		DockerDisableV1Ping:         true,
	}

	log.Printf("[NewImageSource] start!!!")
	imgSrc, err := srcRef.NewImageSource(tools.Timeout(60), systemCtx)
	if err != nil {
		log.Panic(1, err)
	}

	log.Printf("[GetManifest] start!!!")
	bs, str, err := imgSrc.GetManifest(tools.Timeout(5), nil)
	if err != nil {
		log.Panic(2, err)
	}

	log.Printf("[manifest] bs=%s str=%s", string(bs), str)

	var (
		m = new(M)
		d string
	)
	if err = json.Unmarshal(bs, m); err != nil {
		log.Panic(3, err)
	}

	for _, item := range m.Manifests {
		if item.Platform.Os == "linux" && item.Platform.Architecture == runtime.GOARCH {
			d = item.Digest
			break
		}
	}

	if d == "" {
		log.Panicf("[4] empty digest: %s - %s", runtime.GOOS, runtime.GOARCH)
	}

	rc, size, err := imgSrc.GetBlob(tools.Timeout(60),
		types.BlobInfo{
			Digest: digest.Digest(d),
		}, blobinfocache.DefaultCache(systemCtx))
	if err != nil {
		log.Panic(5, err)
	}

	log.Printf("[GetBlob] size=%d", size)

	rc.Close()
}