Merge pull request #678 from umohnani8/kpod_save

Add 'kpod save' command

cmd/kpod/main.go

@@ -31,6 +31,7 @@ func main() {
 		rmiCommand,
 		tagCommand,
 		versionCommand,
+		saveCommand,
 	}
 	app.Flags = []cli.Flag{
 		cli.StringFlag{

cmd/kpod/save.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"os"
+
+	"github.com/Sirupsen/logrus"
+	"github.com/containers/storage"
+	libkpodimage "github.com/kubernetes-incubator/cri-o/libkpod/image"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+const (
+	dockerArchive = "docker-archive:"
+)
+
+type saveOptions struct {
+	output string
+	quiet  bool
+	images []string
+}
+
+var (
+	saveFlags = []cli.Flag{
+		cli.StringFlag{
+			Name:  "output, o",
+			Usage: "Write to a file, default is STDOUT",
+			Value: "/dev/stdout",
+		},
+		cli.BoolFlag{
+			Name:  "quiet, q",
+			Usage: "Suppress the output",
+		},
+	}
+	saveDescription = "Save an image to docker-archive on the local machine"
+	saveCommand     = cli.Command{
+		Name:        "save",
+		Usage:       "Save image to an archive",
+		Description: saveDescription,
+		Flags:       saveFlags,
+		Action:      saveCmd,
+		ArgsUsage:   "",
+	}
+)
+
+// saveCmd saves the image to either docker-archive or oci
+func saveCmd(c *cli.Context) error {
+	args := c.Args()
+	if len(args) == 0 {
+		return errors.Errorf("need at least 1 argument")
+	}
+
+	store, err := getStore(c)
+	if err != nil {
+		return err
+	}
+
+	output := c.String("output")
+	quiet := c.Bool("quiet")
+
+	if output == "/dev/stdout" {
+		fi := os.Stdout
+		if logrus.IsTerminal(fi) {
+			return errors.Errorf("refusing to save to terminal. Use -o flag or redirect")
+		}
+	}
+
+	opts := saveOptions{
+		output: output,
+		quiet:  quiet,
+		images: args,
+	}
+
+	return saveImage(store, opts)
+}
+
+// saveImage pushes the image to docker-archive or oci by
+// calling pushImageForSave
+func saveImage(store storage.Store, opts saveOptions) error {
+	dst := dockerArchive + opts.output
+
+	pushOpts := libkpodimage.CopyOptions{
+		SignaturePolicyPath: "",
+		Store:               store,
+	}
+
+	// only one image is supported for now
+	// future pull requests will fix this
+	for _, image := range opts.images {
+		dest := dst + ":" + image
+		if err := libkpodimage.PushImage(image, dest, pushOpts); err != nil {
+			return errors.Wrapf(err, "unable to save %q", image)
+		}
+	}
+	return nil
+}