Add support for zstd compression

cmd/executor/cmd/root.go

@@ -225,6 +225,8 @@ func addKanikoOptionsFlags() {
 	RootCmd.PersistentFlags().StringVarP(&opts.ImageNameDigestFile, "image-name-with-digest-file", "", "", "Specify a file to save the image name w/ digest of the built image to.")
 	RootCmd.PersistentFlags().StringVarP(&opts.ImageNameTagDigestFile, "image-name-tag-with-digest-file", "", "", "Specify a file to save the image name w/ image tag w/ digest of the built image to.")
 	RootCmd.PersistentFlags().StringVarP(&opts.OCILayoutPath, "oci-layout-path", "", "", "Path to save the OCI image layout of the built image.")
+	RootCmd.PersistentFlags().VarP(&opts.Compression, "compression", "", "Compression algorithm (gzip, zstd)")
+	RootCmd.PersistentFlags().IntVarP(&opts.CompressionLevel, "compression-level", "", -1, "Compression level")
 	RootCmd.PersistentFlags().BoolVarP(&opts.Cache, "cache", "", false, "Use cache when building image")
 	RootCmd.PersistentFlags().BoolVarP(&opts.CompressedCaching, "compressed-caching", "", true, "Compress the cached layers. Decreases build time, but increases memory usage.")
 	RootCmd.PersistentFlags().BoolVarP(&opts.Cleanup, "cleanup", "", false, "Clean the filesystem at the end")

pkg/config/options.go

@@ -68,6 +68,8 @@ type KanikoOptions struct {
 	ImageNameDigestFile      string
 	ImageNameTagDigestFile   string
 	OCILayoutPath            string
+	Compression              Compression
+	CompressionLevel         int
 	ImageFSExtractRetry      int
 	SingleSnapshot           bool
 	Reproducible             bool
@@ -125,6 +127,33 @@ func (k *KanikoGitOptions) Set(s string) error {
 	return nil
 }
 
+// Compression is an enumeration of the supported compression algorithms
+type Compression string
+
+// The collection of known MediaType values.
+const (
+	GZip Compression = "gzip"
+	ZStd Compression = "zstd"
+)
+
+func (c *Compression) String() string {
+	return string(*c)
+}
+
+func (c *Compression) Set(v string) error {
+	switch v {
+	case "gzip", "zstd":
+		*c = Compression(v)
+		return nil
+	default:
+		return errors.New(`must be either "gzip" or "zstd"`)
+	}
+}
+
+func (c *Compression) Type() string {
+	return "compression"
+}
+
 // WarmerOptions are options that are set by command line arguments to the cache warmer.
 type WarmerOptions struct {
 	CacheOptions

pkg/executor/build.go

@@ -515,12 +515,25 @@ func (s *stageBuilder) saveSnapshotToLayer(tarPath string) (v1.Layer, error) {
 		return nil, nil
 	}
 
-	var layer v1.Layer
+	var layerOpts []tarball.LayerOption
+
 	if s.opts.CompressedCaching == true {
-		layer, err = tarball.LayerFromFile(tarPath, tarball.WithCompressedCaching)
-	} else {
-		layer, err = tarball.LayerFromFile(tarPath)
+		layerOpts = append(layerOpts, tarball.WithCompressedCaching)
+	}
+
+	if s.opts.CompressionLevel > 0 {
+		layerOpts = append(layerOpts, tarball.WithCompressionLevel(s.opts.CompressionLevel))
 	}
+
+	switch s.opts.Compression {
+	case config.ZStd:
+		layerOpts = append(layerOpts, tarball.WithCompression("zstd"))
+
+	case config.GZip:
+		// layer already gzipped by default
+	}
+
+	layer, err := tarball.LayerFromFile(tarPath, layerOpts...)
 	if err != nil {
 		return nil, err
 	}

pkg/executor/push.go

@@ -296,16 +296,28 @@ func writeImageOutputs(image v1.Image, destRefs []name.Tag) error {
 // pushLayerToCache pushes layer (tagged with cacheKey) to opts.CacheRepo
 // if opts.CacheRepo doesn't exist, infer the cache from the given destination
 func pushLayerToCache(opts *config.KanikoOptions, cacheKey string, tarPath string, createdBy string) error {
-	var layer v1.Layer
-	var err error
+	var layerOpts []tarball.LayerOption
 	if opts.CompressedCaching == true {
-		layer, err = tarball.LayerFromFile(tarPath, tarball.WithCompressedCaching)
-	} else {
-		layer, err = tarball.LayerFromFile(tarPath)
+		layerOpts = append(layerOpts, tarball.WithCompressedCaching)
 	}
+
+	if opts.CompressionLevel > 0 {
+		layerOpts = append(layerOpts, tarball.WithCompressionLevel(opts.CompressionLevel))
+	}
+
+	switch opts.Compression {
+	case config.ZStd:
+		layerOpts = append(layerOpts, tarball.WithCompression("zstd"))
+
+	case config.GZip:
+		// layer already gzipped by default
+	}
+
+	layer, err := tarball.LayerFromFile(tarPath, layerOpts...)
 	if err != nil {
 		return err
 	}
+
 	cache, err := cache.Destination(opts, cacheKey)
 	if err != nil {
 		return errors.Wrap(err, "getting cache destination")