Use tarball.LayerFromOpener

tarball.LayerFromReader slurps the whole src in memory. The payoff is
that we might read the file multiple time as internally it's called
multiple times.

cmd/util.go

@@ -28,7 +28,6 @@ import (
 	fileHelper "github.com/mudler/luet/pkg/helpers/file"
 	"github.com/pkg/errors"
 
-	containerdCompression "github.com/containerd/containerd/archive/compression"
 	"github.com/mudler/luet/cmd/util"
 	"github.com/mudler/luet/pkg/helpers/docker"
 
@@ -36,16 +35,6 @@ import (
 )
 
 func pack(ctx *luettypes.Context, p, dst, imageName, arch, OS string) error {
-	archiveFile, err := os.Open(p)
-	if err != nil {
-		return errors.Wrap(err, "Cannot open "+p)
-	}
-	defer archiveFile.Close()
-
-	decompressed, err := containerdCompression.DecompressStream(archiveFile)
-	if err != nil {
-		return errors.Wrap(err, "Cannot open "+p)
-	}
 
 	tempimage, err := ctx.Config.GetSystem().TempFile("tempimage")
 	if err != nil {
@@ -53,7 +42,7 @@ func pack(ctx *luettypes.Context, p, dst, imageName, arch, OS string) error {
 	}
 	defer os.RemoveAll(tempimage.Name()) // clean up
 
-	if err := image.CreateTarReader(decompressed, tempimage.Name(), imageName, arch, OS); err != nil {
+	if err := image.CreateTar(p, tempimage.Name(), imageName, arch, OS); err != nil {
 		return errors.Wrap(err, "could not create image from tar")
 	}
 

pkg/api/core/image/create.go

@@ -19,6 +19,7 @@ import (
 	"io"
 	"os"
 
+	containerdCompression "github.com/containerd/containerd/archive/compression"
 	"github.com/google/go-containerregistry/pkg/name"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/empty"
@@ -27,13 +28,13 @@ import (
 	"github.com/pkg/errors"
 )
 
-func imageFromTar(imagename, architecture, OS string, r io.Reader) (name.Reference, v1.Image, error) {
+func imageFromTar(imagename, architecture, OS string, opener func() (io.ReadCloser, error)) (name.Reference, v1.Image, error) {
 	newRef, err := name.ParseReference(imagename)
 	if err != nil {
 		return nil, nil, err
 	}
 
-	layer, err := tarball.LayerFromReader(r)
+	layer, err := tarball.LayerFromOpener(opener)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -67,28 +68,30 @@ func imageFromTar(imagename, architecture, OS string, r io.Reader) (name.Referen
 
 // CreateTar a imagetarball from a standard tarball
 func CreateTar(srctar, dstimageTar, imagename, architecture, OS string) error {
-	f, err := os.Open(srctar)
-	if err != nil {
-		return errors.Wrap(err, "Cannot open "+srctar)
-	}
-	defer f.Close()
 
-	return CreateTarReader(f, dstimageTar, imagename, architecture, OS)
-}
-
-// CreateTarReader a imagetarball from a standard tarball
-func CreateTarReader(r io.Reader, dstimageTar, imagename, architecture, OS string) error {
 	dstFile, err := os.Create(dstimageTar)
 	if err != nil {
 		return errors.Wrap(err, "Cannot create "+dstimageTar)
 	}
 	defer dstFile.Close()
 
-	newRef, img, err := imageFromTar(imagename, architecture, OS, r)
+	newRef, img, err := imageFromTar(imagename, architecture, OS, func() (io.ReadCloser, error) {
+		f, err := os.Open(srctar)
+		if err != nil {
+			return nil, errors.Wrap(err, "Cannot open "+srctar)
+		}
+		decompressed, err := containerdCompression.DecompressStream(f)
+		if err != nil {
+			return nil, errors.Wrap(err, "Cannot open "+srctar)
+		}
+
+		return decompressed, nil
+	})
 	if err != nil {
 		return err
 	}
 
 	// NOTE: We might also stream that back to the daemon with daemon.Write(tag, img)
 	return tarball.Write(newRef, img, dstFile)
+
 }

pkg/api/core/types/artifact/artifact.go

@@ -211,16 +211,6 @@ type ImageBuilder interface {
 
 // GenerateFinalImage takes an artifact and builds a Docker image with its content
 func (a *PackageArtifact) GenerateFinalImage(ctx *types.Context, imageName string, b ImageBuilder, keepPerms bool) error {
-	archiveFile, err := os.Open(a.Path)
-	if err != nil {
-		return errors.Wrap(err, "Cannot open "+a.Path)
-	}
-	defer archiveFile.Close()
-
-	decompressed, err := containerdCompression.DecompressStream(archiveFile)
-	if err != nil {
-		return errors.Wrap(err, "Cannot open "+a.Path)
-	}
 
 	tempimage, err := ctx.Config.GetSystem().TempFile("tempimage")
 	if err != nil {
@@ -228,7 +218,7 @@ func (a *PackageArtifact) GenerateFinalImage(ctx *types.Context, imageName strin
 	}
 	defer os.RemoveAll(tempimage.Name()) // clean up
 
-	if err := image.CreateTarReader(decompressed, tempimage.Name(), imageName, runtime.GOARCH, runtime.GOOS); err != nil {
+	if err := image.CreateTar(a.Path, tempimage.Name(), imageName, runtime.GOARCH, runtime.GOOS); err != nil {
 		return errors.Wrap(err, "could not create image from tar")
 	}