feat: add igzip/pigz compression-variant

Author: okhowang

README.md

@@ -289,6 +289,7 @@ Keys supported by image output:
 * `dangling-name-prefix=<value>`: name image with `prefix@<digest>`, used for anonymous images
 * `name-canonical=true`: add additional canonical name `name@<digest>`
 * `compression=<uncompressed|gzip|estargz|zstd>`: choose compression type for layers newly created and cached, gzip is default value. estargz should be used with `oci-mediatypes=true`.
+* `compression-variant=<gzip|igzip|pigz>`: choose different compression method for gzip, only worked with `compression=gzip`.
 * `compression-level=<value>`: compression level for gzip, estargz (0-9) and zstd (0-22)
 * `rewrite-timestamp=true`: rewrite the file timestamps to the `SOURCE_DATE_EPOCH` value.
    See [`docs/build-repro.md`](docs/build-repro.md) for how to specify the `SOURCE_DATE_EPOCH` value.
@@ -467,6 +468,7 @@ buildctl build ... \
 * `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `true` since BuildKit `v0.21`, must be used with `oci-mediatypes=true`)
 * `oci-mediatypes=<true|false>`: whether to use OCI mediatypes in exported manifests (default: `true`, since BuildKit `v0.8`)
 * `compression=<uncompressed|gzip|estargz|zstd>`: choose compression type for layers newly created and cached, gzip is default value. estargz and zstd should be used with `oci-mediatypes=true`
+* `compression-variant=<gzip|igzip|pigz>`: choose different compression method for gzip, only worked with `compression=gzip`.
 * `compression-level=<value>`: choose compression level for gzip, estargz (0-9) and zstd (0-22)
 * `force-compression=true`: forcibly apply `compression` option to all layers
 * `ignore-error=<false|true>`: specify if error is ignored in case cache export fails (default: `false`)
@@ -494,6 +496,7 @@ The directory layout conforms to OCI Image Spec v1.0.
 * `image-manifest=<true|false>`: whether to export cache manifest as an OCI-compatible image manifest rather than a manifest list/index (default: `true` since BuildKit `v0.21`, must be used with `oci-mediatypes=true`)
 * `oci-mediatypes=<true|false>`: whether to use OCI mediatypes in exported manifests (default `true`, since BuildKit `v0.8`)
 * `compression=<uncompressed|gzip|estargz|zstd>`: choose compression type for layers newly created and cached, gzip is default value. estargz and zstd should be used with `oci-mediatypes=true`.
+* `compression-variant=<gzip|igzip|pigz>`: choose different compression method for gzip, only worked with `compression=gzip`.
 * `compression-level=<value>`: compression level for gzip, estargz (0-9) and zstd (0-22)
 * `force-compression=true`: forcibly apply `compression` option to all layers
 * `ignore-error=<false|true>`: specify if error is ignored in case cache export fails (default: `false`)

util/compression/attrs.go

@@ -7,9 +7,10 @@ import (
 )
 
 const (
-	attrLayerCompression = "compression"
-	attrForceCompression = "force-compression"
-	attrCompressionLevel = "compression-level"
+	attrLayerCompression   = "compression"
+	attrForceCompression   = "force-compression"
+	attrCompressionLevel   = "compression-level"
+	attrCompressionVariant = "compression-variant"
 )
 
 func ParseAttributes(attrs map[string]string) (Config, error) {
@@ -44,5 +45,8 @@ func ParseAttributes(attrs map[string]string) (Config, error) {
 		}
 		compressionConfig = compressionConfig.SetLevel(int(ii))
 	}
+	if v, ok := attrs[attrCompressionVariant]; ok {
+		compressionConfig = compressionConfig.SetVariant(v)
+	}
 	return compressionConfig, nil
 }

util/compression/compression.go

@@ -54,9 +54,10 @@ var (
 )
 
 type Config struct {
-	Type  Type
-	Force bool
-	Level *int
+	Type    Type
+	Force   bool
+	Level   *int
+	Variant string
 }
 
 func New(t Type) Config {
@@ -75,6 +76,11 @@ func (c Config) SetLevel(l int) Config {
 	return c
 }
 
+func (c Config) SetVariant(v string) Config {
+	c.Variant = v
+	return c
+}
+
 const (
 	mediaTypeDockerSchema2LayerZstd = images.MediaTypeDockerSchema2Layer + ".zstd"
 )

util/compression/gzip.go

@@ -1,9 +1,13 @@
 package compression
 
 import (
+	"bytes"
 	"compress/gzip"
 	"context"
+	"errors"
+	"fmt"
 	"io"
+	"os/exec"
 
 	"github.com/containerd/containerd/v2/core/content"
 	"github.com/containerd/containerd/v2/core/images"
@@ -12,6 +16,12 @@ import (
 
 func (c gzipType) Compress(ctx context.Context, comp Config) (compressorFunc Compressor, finalize Finalizer) {
 	return func(dest io.Writer, _ string) (io.WriteCloser, error) {
+		switch comp.Variant {
+		case "igzip":
+			return gzipCmdWriter(ctx, "igzip", comp)(dest)
+		case "pigz":
+			return gzipCmdWriter(ctx, "pigz", comp)(dest)
+		}
 		return gzipWriter(comp)(dest)
 	}, nil
 }
@@ -64,3 +74,44 @@ func gzipWriter(comp Config) func(io.Writer) (io.WriteCloser, error) {
 		return gzip.NewWriterLevel(dest, level)
 	}
 }
+
+type writeCloserWrapper struct {
+	io.Writer
+	closer func() error
+}
+
+func (w *writeCloserWrapper) Close() error {
+	return w.closer()
+}
+
+func gzipCmdWriter(ctx context.Context, cmd string, comp Config) func(io.Writer) (io.WriteCloser, error) {
+	return func(dest io.Writer) (io.WriteCloser, error) {
+		reader, writer := io.Pipe()
+		args := []string{"-c"}
+		if comp.Level != nil {
+			args = append(args, fmt.Sprintf("-%d", *comp.Level))
+		}
+		command := exec.CommandContext(ctx, cmd, args...)
+		command.Stdin = reader
+		command.Stdout = dest
+
+		var errBuf bytes.Buffer
+		command.Stderr = &errBuf
+
+		if err := command.Start(); err != nil {
+			return nil, err
+		}
+
+		return &writeCloserWrapper{
+			Writer: writer,
+			closer: func() error {
+				closeErr := writer.Close()
+				waitErr := command.Wait()
+				if waitErr != nil {
+					return fmt.Errorf("%s: %s", waitErr, errBuf.String())
+				}
+				return errors.Join(closeErr, waitErr)
+			},
+		}, nil
+	}
+}