1 files changed, 128 insertions, 0 deletions
diff --git a/cmd/kpod/diff.go b/cmd/kpod/diff.go
new file mode 100644
index 000000000..c28bdfce6
--- /dev/null
+++ b/cmd/kpod/diff.go
@@ -0,0 +1,128 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/containers/storage/pkg/archive"
+	"github.com/kubernetes-incubator/cri-o/cmd/kpod/formats"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+type diffJSONOutput struct {
+	Changed []string `json:"changed,omitempty"`
+	Added   []string `json:"added,omitempty"`
+	Deleted []string `json:"deleted,omitempty"`
+}
+
+type diffOutputParams struct {
+	Change archive.ChangeType
+	Path   string
+}
+
+type stdoutStruct struct {
+	output []diffOutputParams
+}
+
+func (so stdoutStruct) Out() error {
+	for _, d := range so.output {
+		fmt.Printf("%s %s\n", d.Change, d.Path)
+	}
+	return nil
+}
+
+var (
+	diffFlags = []cli.Flag{
+		cli.BoolFlag{
+			Name:   "archive",
+			Usage:  "Save the diff as a tar archive",
+			Hidden: true,
+		},
+		cli.StringFlag{
+			Name:  "format",
+			Usage: "Change the output format.",
+		},
+	}
+	diffDescription = fmt.Sprint(`Displays changes on a container or image's filesystem.  The
+	container or image will be compared to its parent layer`)
+
+	diffCommand = cli.Command{
+		Name:        "diff",
+		Usage:       "Inspect changes on container's file systems",
+		Description: diffDescription,
+		Flags:       diffFlags,
+		Action:      diffCmd,
+		ArgsUsage:   "ID-NAME",
+	}
+)
+
+func formatJSON(output []diffOutputParams) (diffJSONOutput, error) {
+	jsonStruct := diffJSONOutput{}
+	for _, output := range output {
+		switch output.Change {
+		case archive.ChangeModify:
+			jsonStruct.Changed = append(jsonStruct.Changed, output.Path)
+		case archive.ChangeAdd:
+			jsonStruct.Added = append(jsonStruct.Added, output.Path)
+		case archive.ChangeDelete:
+			jsonStruct.Deleted = append(jsonStruct.Deleted, output.Path)
+		default:
+			return jsonStruct, errors.Errorf("output kind %q not recognized", output.Change.String())
+		}
+	}
+	return jsonStruct, nil
+}
+
+func diffCmd(c *cli.Context) error {
+	if err := validateFlags(c, diffFlags); err != nil {
+		return err
+	}
+
+	if len(c.Args()) != 1 {
+		return errors.Errorf("container, image, or layer name must be specified: kpod diff [options [...]] ID-NAME")
+	}
+
+	runtime, err := getRuntime(c)
+	if err != nil {
+		return errors.Wrapf(err, "could not get runtime")
+	}
+	defer runtime.Shutdown(false)
+
+	to := c.Args().Get(0)
+	changes, err := runtime.GetDiff("", to)
+	if err != nil {
+		return errors.Wrapf(err, "could not get changes for %q", to)
+	}
+
+	diffOutput := []diffOutputParams{}
+	outputFormat := c.String("format")
+
+	for _, change := range changes {
+
+		params := diffOutputParams{
+			Change: change.Kind,
+			Path:   change.Path,
+		}
+		diffOutput = append(diffOutput, params)
+	}
+
+	var out formats.Writer
+
+	if outputFormat != "" {
+		switch outputFormat {
+		case formats.JSONString:
+			data, err := formatJSON(diffOutput)
+			if err != nil {
+				return err
+			}
+			out = formats.JSONStruct{Output: data}
+		default:
+			return errors.New("only valid format for diff is 'json'")
+		}
+	} else {
+		out = stdoutStruct{output: diffOutput}
+	}
+	formats.Writer(out).Out()
+
+	return nil
+}