1 files changed, 89 insertions, 0 deletions
diff --git a/cmd/crane/cmd/export.go b/cmd/crane/cmd/export.go
new file mode 100644
index 0000000..70b58c1
--- /dev/null
+++ b/cmd/crane/cmd/export.go
@@ -0,0 +1,89 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"os"
+
+	"github.com/google/go-containerregistry/pkg/crane"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/tarball"
+	"github.com/spf13/cobra"
+)
+
+// NewCmdExport creates a new cobra.Command for the export subcommand.
+func NewCmdExport(options *[]crane.Option) *cobra.Command {
+	return &cobra.Command{
+		Use:   "export IMAGE|- TARBALL|-",
+		Short: "Export filesystem of a container image as a tarball",
+		Example: `  # Write tarball to stdout
+  crane export ubuntu -
+
+  # Write tarball to file
+  crane export ubuntu ubuntu.tar
+
+  # Read image from stdin
+  crane export - ubuntu.tar`,
+		Args: cobra.RangeArgs(1, 2),
+		RunE: func(_ *cobra.Command, args []string) error {
+			src, dst := args[0], "-"
+			if len(args) > 1 {
+				dst = args[1]
+			}
+
+			f, err := openFile(dst)
+			if err != nil {
+				return fmt.Errorf("failed to open %s: %w", dst, err)
+			}
+			defer f.Close()
+
+			var img v1.Image
+			if src == "-" {
+				tmpfile, err := os.CreateTemp("", "crane")
+				if err != nil {
+					log.Fatal(err)
+				}
+				defer os.Remove(tmpfile.Name())
+
+				if _, err := io.Copy(tmpfile, os.Stdin); err != nil {
+					log.Fatal(err)
+				}
+				tmpfile.Close()
+
+				img, err = tarball.ImageFromPath(tmpfile.Name(), nil)
+				if err != nil {
+					return fmt.Errorf("reading tarball from stdin: %w", err)
+				}
+			} else {
+				img, err = crane.Pull(src, *options...)
+				if err != nil {
+					return fmt.Errorf("pulling %s: %w", src, err)
+				}
+			}
+
+			return crane.Export(img, f)
+		},
+	}
+}
+
+func openFile(s string) (*os.File, error) {
+	if s == "-" {
+		return os.Stdout, nil
+	}
+	return os.Create(s)
+}