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

@@ -6,6 +6,7 @@ import (
 	"io"
 	"strings"
 
+	"github.com/containers/image/pkg/compression"
 	"github.com/containers/image/transports/alltransports"
 	"github.com/containers/image/types"
 	"github.com/urfave/cli"
@@ -153,9 +154,11 @@ func (opts *imageOptions) newSystemContext() (*types.SystemContext, error) {
 // imageDestOptions is a superset of imageOptions specialized for iamge destinations.
 type imageDestOptions struct {
 	*imageOptions
-	osTreeTmpDir                string // A directory to use for OSTree temporary files
-	dirForceCompression         bool   // Compress layers when saving to the dir: transport
-	ociAcceptUncompressedLayers bool   // Whether to accept uncompressed layers in the oci: transport
+	osTreeTmpDir                string      // A directory to use for OSTree temporary files
+	dirForceCompression         bool        // Compress layers when saving to the dir: transport
+	ociAcceptUncompressedLayers bool        // Whether to accept uncompressed layers in the oci: transport
+	compressionFormat           string      // Format to use for the compression
+	compressionLevel            optionalInt // Level to use for the compression
 }
 
 // imageDestFlags prepares a collection of CLI flags writing into imageDestOptions, and the managed imageDestOptions structure.
@@ -179,6 +182,16 @@ func imageDestFlags(global *globalOptions, shared *sharedImageOptions, flagPrefi
 			Usage:       "Allow uncompressed image layers when saving to an OCI image using the 'oci' transport. (default is to compress things that aren't compressed)",
 			Destination: &opts.ociAcceptUncompressedLayers,
 		},
+		cli.StringFlag{
+			Name:        flagPrefix + "compress-format",
+			Usage:       "`FORMAT` to use for the compression",
+			Destination: &opts.compressionFormat,
+		},
+		cli.GenericFlag{
+			Name:  flagPrefix + "compress-level",
+			Usage: "`LEVEL` to use for the compression",
+			Value: newOptionalIntValue(&opts.compressionLevel),
+		},
 	}...), &opts
 }
 
@@ -193,6 +206,17 @@ func (opts *imageDestOptions) newSystemContext() (*types.SystemContext, error) {
 	ctx.OSTreeTmpDirPath = opts.osTreeTmpDir
 	ctx.DirForceCompress = opts.dirForceCompression
 	ctx.OCIAcceptUncompressedLayers = opts.ociAcceptUncompressedLayers
+	if opts.compressionFormat == "" {
+		opts.compressionFormat = "gzip"
+	}
+	cf, err := compression.AlgorithmByName(opts.compressionFormat)
+	if err != nil {
+		return nil, err
+	}
+	ctx.CompressionFormat = cf
+	if opts.compressionLevel.present {
+		ctx.CompressionLevel = &opts.compressionLevel.value
+	}
 	return ctx, err
 }
 

docs/skopeo-copy.1.md

@@ -58,6 +58,10 @@ 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.  The value is specific to the compression algorithm used, e.g. for zstd the accepted values are in the range 1-20 (inclusive), while for gzip it is 1-9 (inclusive).  Algorithms that don't support the setting, will ignore it.
+
 ## EXAMPLES
 
 To copy the layers of the docker.io busybox image to a local directory:

go.mod

@@ -3,20 +3,15 @@ module github.com/containers/skopeo
 go 1.12
 
 require (
-	github.com/BurntSushi/toml v0.3.1 // indirect
-	github.com/Microsoft/go-winio v0.4.12 // indirect
-	github.com/Microsoft/hcsshim v0.8.6 // indirect
 	github.com/VividCortex/ewma v1.1.1 // indirect
 	github.com/containerd/continuity v0.0.0-20180216233310-d8fb8589b0e8 // indirect
 	github.com/containers/buildah v1.8.4
 	github.com/containers/image v1.5.2-0.20190725091050-48acc3dcbb76
-	github.com/containers/storage v1.12.10
-	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/containers/storage v1.12.14
 	github.com/docker/distribution v0.0.0-20170817175659-5f6282db7d65 // indirect
 	github.com/docker/docker v0.0.0-20180522102801-da99009bbb11
 	github.com/docker/docker-credential-helpers v0.6.0 // indirect
 	github.com/docker/go-connections v0.0.0-20180212134524-7beb39f0b969 // indirect
-	github.com/docker/go-units v0.0.0-20161020213227-8a7beacffa30 // indirect
 	github.com/docker/libtrust v0.0.0-20160708172513-aabc10ec26b7 // indirect
 	github.com/etcd-io/bbolt v1.3.2 // indirect
 	github.com/ghodss/yaml v0.0.0-20150909031657-73d445a93680 // indirect
@@ -25,42 +20,29 @@ require (
 	github.com/gorilla/context v0.0.0-20140604161150-14f550f51af5 // indirect
 	github.com/gorilla/mux v0.0.0-20140926153814-e444e69cbd2e // indirect
 	github.com/imdario/mergo v0.0.0-20141206190957-6633656539c1 // indirect
-	github.com/klauspost/compress v1.4.1 // indirect
-	github.com/klauspost/cpuid v1.2.0 // indirect
-	github.com/klauspost/pgzip v1.2.1 // indirect
 	github.com/kr/pretty v0.1.0 // indirect
 	github.com/mattn/go-isatty v0.0.4 // indirect
-	github.com/mattn/go-shellwords v1.0.5 // indirect
-	github.com/mistifyio/go-zfs v0.0.0-20160425201758-22c9b32c84eb // indirect
 	github.com/mtrmac/gpgme v0.0.0-20170102180018-b2432428689c // indirect
-	github.com/opencontainers/go-digest v0.0.0-20180430190053-c9281466c8b2
+	github.com/opencontainers/go-digest v1.0.0-rc1
 	github.com/opencontainers/image-spec v0.0.0-20180918080442-7b1e489870ac
 	github.com/opencontainers/image-tools v0.0.0-20170926011501-6d941547fa1d
-	github.com/opencontainers/runc v1.0.0-rc6 // indirect
 	github.com/opencontainers/runtime-spec v1.0.0 // indirect
-	github.com/opencontainers/selinux v0.0.0-20190118194635-b707dfcb00a1 // indirect
-	github.com/ostreedev/ostree-go v0.0.0-20181204105935-56f3a639dbc0 // indirect
 	github.com/pborman/uuid v0.0.0-20160209185913-a97ce2ca70fa // indirect
 	github.com/pkg/errors v0.8.1
-	github.com/pmezard/go-difflib v0.0.0-20181226105442-5d4384ee4fb2 // indirect
-	github.com/pquerna/ffjson v0.0.0-20171002144729-d49c2bc1aa13 // indirect
-	github.com/sirupsen/logrus v1.0.0
-	github.com/stretchr/testify v1.1.3
+	github.com/sirupsen/logrus v1.4.2
+	github.com/stretchr/testify v1.3.0
 	github.com/syndtr/gocapability v0.0.0-20180916011248-d98352740cb2
-	github.com/tchap/go-patricia v2.2.6+incompatible // indirect
 	github.com/ulikunitz/xz v0.5.4 // indirect
 	github.com/urfave/cli v1.20.0
-	github.com/vbatts/tar-split v0.10.2 // indirect
 	github.com/vbauerster/mpb v3.4.0+incompatible // indirect
 	github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	github.com/xeipuuv/gojsonschema v1.1.0 // indirect
 	go4.org v0.0.0-20190218023631-ce4c26f7be8e // indirect
-	golang.org/x/crypto v0.0.0-20190219172222-a4c6cb3142f2 // indirect
-	golang.org/x/net v0.0.0-20190107210223-45ffb0cd1ba0 // indirect
 	golang.org/x/sync v0.0.0-20181108010431-42b317875d0f // indirect
-	golang.org/x/sys v0.0.0-20170817234608-43e60d72a8e2 // indirect
-	golang.org/x/text v0.0.0-20181227161524-e6919f6577db // indirect
+	golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e // indirect
 	gopkg.in/yaml.v2 v2.0.0-20141029210843-d466437aa4ad // indirect
 	k8s.io/client-go v0.0.0-20181219152756-3dd551c0f083 // indirect
 )
+
+replace github.com/containers/image => github.com/giuseppe/image v0.0.0-20190723195852-da7a70cbb5f1