copy: add --dest-compress-format and --dest-compress-level

add the possibility to specify the format and the level to use when
compressing blobs.

Signed-off-by: Giuseppe Scrivano <[email protected]>

cmd/skopeo/utils.go

@@ -155,6 +155,8 @@ type imageDestOptions struct {
 	*imageOptions
 	osTreeTmpDir        string // A directory to use for OSTree temporary files
 	dirForceCompression bool   // Compress layers when saving to the dir: transport
+	compressionFormat   string // Format to use for the compression
+	compressionLevel    int    // Level to use for the compression
 }
 
 // imageDestFlags prepares a collection of CLI flags writing into imageDestOptions, and the managed imageDestOptions structure.
@@ -173,6 +175,16 @@ func imageDestFlags(global *globalOptions, shared *sharedImageOptions, flagPrefi
 			Usage:       "Compress tarball image layers when saving to directory using the 'dir' transport. (default is same compression type as source)",
 			Destination: &opts.dirForceCompression,
 		},
+		cli.StringFlag{
+			Name:        flagPrefix + "compress-format",
+			Usage:       "`FORMAT` to use for the compression",
+			Destination: &opts.compressionFormat,
+		},
+		cli.IntFlag{
+			Name:        flagPrefix + "compress-level",
+			Usage:       "`LEVEL` to use for the compression",
+			Destination: &opts.compressionLevel,
+		},
 	}...), &opts
 }
 
@@ -186,6 +198,8 @@ func (opts *imageDestOptions) newSystemContext() (*types.SystemContext, error) {
 
 	ctx.OSTreeTmpDirPath = opts.osTreeTmpDir
 	ctx.DirForceCompress = opts.dirForceCompression
+	ctx.CompressionFormat = opts.compressionFormat
+	ctx.CompressionLevel = opts.compressionLevel
 	return ctx, err
 }
 

docs/skopeo-copy.1.md

@@ -56,6 +56,10 @@ If the authorization state is not found there, $HOME/.docker/config.json is chec
 
 Existing signatures, if any, are preserved as well.
 
+**--dest-compress-format** _format_ Specifies the compression format to use.
+
+**--dest-compress-level** _format_ Specifies the compression level to use.
+
 ## EXAMPLES
 
 To copy the layers of the docker.io busybox image to a local directory:

vendor.conf

@@ -2,14 +2,14 @@
 github.com/urfave/cli v1.20.0
 github.com/kr/pretty v0.1.0
 github.com/kr/text v0.1.0
-github.com/containers/image 2c0349c99af7d90694b3faa0e9bde404d407b145
+github.com/containers/image zstd https://github.com/giuseppe/image
 github.com/containers/buildah 810efa340ab43753034e2ed08ec290e4abab7e72
 github.com/vbauerster/mpb v3.3.4
 github.com/mattn/go-isatty v0.0.4
 github.com/VividCortex/ewma v1.1.1
 golang.org/x/sync 42b317875d0fa942474b76e1b46a6060d720ae6e
 github.com/opencontainers/go-digest c9281466c8b2f606084ac71339773efd177436e7
-github.com/containers/storage v1.12.3
+github.com/containers/storage zstd https://github.com/giuseppe/storage
 github.com/sirupsen/logrus v1.0.0
 github.com/go-check/check v1
 github.com/stretchr/testify v1.1.3
@@ -65,3 +65,4 @@ github.com/syndtr/gocapability d98352740cb2c55f81556b63d4a1ec64c5a319c2
 github.com/klauspost/pgzip v1.2.1
 github.com/klauspost/compress v1.4.1
 github.com/klauspost/cpuid v1.2.0
+github.com/DataDog/zstd 1.x