Change OCI Layout publisher to lazy create layout after build.

When using ko with OCI Layout, Git status will always be dirty because the
layout is created before this build. This changes the layout to be created
after the build so that git will be clean. The means that any error creating
the layout won't be seen until after the build.

Signed-off-by: Jeff Mendoza <[email protected]>

pkg/commands/resolver.go

@@ -213,10 +213,7 @@ func makePublisher(po *options.PublishOptions) (publish.Interface, error) {
 
 		publishers := []publish.Interface{}
 		if po.OCILayoutPath != "" {
-			lp, err := publish.NewLayout(po.OCILayoutPath)
-			if err != nil {
-				return nil, fmt.Errorf("failed to create LayoutPublisher for %q: %w", po.OCILayoutPath, err)
-			}
+			lp := publish.NewLayout(po.OCILayoutPath)
 			publishers = append(publishers, lp)
 		}
 		if po.TarballFile != "" {

pkg/publish/layout.go

@@ -28,49 +28,57 @@ import (
 )
 
 type LayoutPublisher struct {
-	p layout.Path
+	p string
 }
 
 // NewLayout returns a new publish.Interface that saves images to an OCI Image Layout.
-func NewLayout(path string) (Interface, error) {
-	p, err := layout.FromPath(path)
+func NewLayout(p string) Interface {
+	return &LayoutPublisher{p}
+}
+
+func (l *LayoutPublisher) writeResult(br build.Result) (layout.Path, error) {
+	p, err := layout.FromPath(l.p)
 	if err != nil {
-		p, err = layout.Write(path, empty.Index)
+		p, err = layout.Write(l.p, empty.Index)
 		if err != nil {
-			return nil, err
+			return "", err
 		}
 	}
-	return &LayoutPublisher{p}, nil
-}
 
-func (l *LayoutPublisher) writeResult(br build.Result) error {
 	mt, err := br.MediaType()
 	if err != nil {
-		return err
+		return "", err
 	}
 
 	switch mt {
 	case types.OCIImageIndex, types.DockerManifestList:
 		idx, ok := br.(v1.ImageIndex)
 		if !ok {
-			return fmt.Errorf("failed to interpret result as index: %v", br)
+			return "", fmt.Errorf("failed to interpret result as index: %v", br)
 		}
-		return l.p.AppendIndex(idx)
+		if err := p.AppendIndex(idx); err != nil {
+			return "", err
+		}
+		return p, nil
 	case types.OCIManifestSchema1, types.DockerManifestSchema2:
 		img, ok := br.(v1.Image)
 		if !ok {
-			return fmt.Errorf("failed to interpret result as image: %v", br)
+			return "", fmt.Errorf("failed to interpret result as image: %v", br)
+		}
+		if err := p.AppendImage(img); err != nil {
+			return "", err
 		}
-		return l.p.AppendImage(img)
+		return p, nil
 	default:
-		return fmt.Errorf("result image media type: %s", mt)
+		return "", fmt.Errorf("result image media type: %s", mt)
 	}
 }
 
 // Publish implements publish.Interface.
 func (l *LayoutPublisher) Publish(_ context.Context, br build.Result, s string) (name.Reference, error) {
 	log.Printf("Saving %v", s)
-	if err := l.writeResult(br); err != nil {
+	p, err := l.writeResult(br)
+	if err != nil {
 		return nil, err
 	}
 	log.Printf("Saved %v", s)
@@ -80,7 +88,7 @@ func (l *LayoutPublisher) Publish(_ context.Context, br build.Result, s string)
 		return nil, err
 	}
 
-	dig, err := name.NewDigest(fmt.Sprintf("%s@%s", l.p, h))
+	dig, err := name.NewDigest(fmt.Sprintf("%s@%s", p, h))
 	if err != nil {
 		return nil, err
 	}

pkg/publish/layout_test.go

@@ -36,10 +36,7 @@ func TestLayout(t *testing.T) {
 	}
 	defer os.RemoveAll(tmp)
 
-	lp, err := NewLayout(tmp)
-	if err != nil {
-		t.Errorf("NewLayout() = %v", err)
-	}
+	lp := NewLayout(tmp)
 	if d, err := lp.Publish(context.Background(), img, importpath); err != nil {
 		t.Errorf("Publish() = %v", err)
 	} else if !strings.HasPrefix(d.String(), tmp) {

pkg/publish/multi_test.go

@@ -48,10 +48,7 @@ func TestMulti(t *testing.T) {
 	}
 	defer os.RemoveAll(tmp)
 
-	lp, err := publish.NewLayout(tmp)
-	if err != nil {
-		t.Errorf("NewLayout() = %v", err)
-	}
+	lp := publish.NewLayout(tmp)
 
 	p := publish.MultiPublisher(lp, tp)
 	if _, err := p.Publish(context.Background(), img, importpath); err != nil {