add base labels

pkg/build/base.go

@@ -11,22 +11,44 @@ import (
 	"github.com/google/go-containerregistry/pkg/v1/remote"
 )
 
-func getBaseImage(ctx BuildContext, baseRef string, platform Platform, keychain authn.Keychain) (v1.Image, error) {
+type BaseImageMetadata struct {
+	name        string
+	imageDigest string
+}
+
+func getBaseImage(ctx BuildContext, baseRef string, platform Platform, keychain authn.Keychain) (v1.Image, BaseImageMetadata, error) {
 	if baseRef == "scratch" {
-		return empty.Image, nil
+		return empty.Image, BaseImageMetadata{
+			name: "scratch",
+		}, nil
 	}
 
 	ref, index, err := fetchImageIndex(ctx, baseRef, keychain)
 	if err != nil {
-		return nil, fmt.Errorf("failed to retrieve base image index: %w", err)
+		return nil, BaseImageMetadata{}, fmt.Errorf("failed to retrieve base image index: %w", err)
 	}
 	baseDigest, err := index.Digest()
 	if err != nil {
-		return nil, fmt.Errorf("failed to retrieve base image digest: %w", err)
+		return nil, BaseImageMetadata{}, fmt.Errorf("failed to retrieve base image index digest: %w", err)
 	}
 	log.Println("Using base image:", ref.Context().Name()+"@"+baseDigest.String())
 
-	return getImageForPlatform(index, platform)
+	img, err := getImageForPlatform(index, platform)
+	if err != nil {
+		return nil, BaseImageMetadata{}, fmt.Errorf("failed to retrieve base image for platform: %w", err)
+	}
+
+	imgDigest, err := img.Digest()
+	if err != nil {
+		return nil, BaseImageMetadata{}, fmt.Errorf("failed to retrieve base image digest: %w", err)
+	}
+
+	metadata := BaseImageMetadata{
+		name:        ref.Context().Name(),
+		imageDigest: imgDigest.String(),
+	}
+
+	return img, metadata, nil
 }
 
 func fetchImageIndex(ctx BuildContext, src string, keychain authn.Keychain) (name.Reference, v1.ImageIndex, error) {

pkg/build/layers.go

@@ -12,6 +12,8 @@ import (
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 )
 
+var unixEpoch = time.Unix(0, 0)
+
 func createLayerFromFolder(ctx BuildContext, layer BuildSpecInjectLayer, opts ...tarball.LayerOption) (v1.Layer, error) {
 	tarPath, err := createTarFromFolder(ctx, layer.SourcePath, layer.DestinationPath)
 	if err != nil {
@@ -31,7 +33,6 @@ func createTarFromFolder(ctx BuildContext, srcPath, dstPath string) (string, err
 	writer := tar.NewWriter(tarFile)
 	defer writer.Close()
 
-	unixEpoch := time.Unix(0, 0)
 	err = filepath.Walk(srcPath, func(file string, fi os.FileInfo, err error) error {
 		if err != nil {
 			return err

pkg/build/root.go

@@ -4,13 +4,13 @@ import (
 	"context"
 	"fmt"
 	"strings"
-	"time"
 
 	"github.com/google/go-containerregistry/pkg/authn"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	"github.com/google/go-containerregistry/pkg/v1/types"
+	specsv1 "github.com/opencontainers/image-spec/specs-go/v1"
 )
 
 type TargetType int
@@ -59,7 +59,7 @@ type BuildContext struct {
 }
 
 func Build(ctx BuildContext, spec BuildSpec) error {
-	baseImage, err := getBaseImage(ctx, spec.BaseRef, spec.InjectLayer.Platform, ctx.Keychain)
+	baseImage, baseMetadata, err := getBaseImage(ctx, spec.BaseRef, spec.InjectLayer.Platform, ctx.Keychain)
 	if err != nil {
 		return fmt.Errorf("failed to retrieve base image: %w", err)
 	}
@@ -74,7 +74,6 @@ func Build(ctx BuildContext, spec BuildSpec) error {
 		return fmt.Errorf("failed to create layer from source: %w", err)
 	}
 
-	unixEpoch := time.Unix(0, 0)
 	newImage, err := mutate.Append(baseImage, mutate.Addendum{
 		Layer:     newLayer,
 		MediaType: mediaType,
@@ -88,15 +87,15 @@ func Build(ctx BuildContext, spec BuildSpec) error {
 		return fmt.Errorf("failed to append layer to base image: %w", err)
 	}
 
-	newImage, err = mutateConfig(newImage, spec)
+	newImage, err = mutateConfig(newImage, spec, baseMetadata)
 	if err != nil {
 		return fmt.Errorf("failed to mutate config: %w", err)
 	}
 
 	return publish(ctx, newImage, spec.Target)
 }
 
-func mutateConfig(img v1.Image, spec BuildSpec) (v1.Image, error) {
+func mutateConfig(img v1.Image, spec BuildSpec, metadata BaseImageMetadata) (v1.Image, error) {
 	imgCfg, err := img.ConfigFile()
 	if err != nil {
 		return nil, err
@@ -106,8 +105,13 @@ func mutateConfig(img v1.Image, spec BuildSpec) (v1.Image, error) {
 	imgCfg.Config.WorkingDir = spec.InjectLayer.DestinationPath
 	imgCfg.Config.Entrypoint = []string{spec.InjectLayer.Entrypoint}
 	imgCfg.Config.Cmd = nil
+
+	imgCfg.Created = v1.Time{Time: unixEpoch}
 	imgCfg.Author = spec.Author
 
+	imgCfg.Config.Labels[specsv1.AnnotationBaseImageName] = metadata.name
+	imgCfg.Config.Labels[specsv1.AnnotationBaseImageDigest] = metadata.imageDigest
+
 	return mutate.ConfigFile(img, imgCfg)
 }