Add -q flag for image ls command

e2e/images_test.go

@@ -1,8 +1,10 @@
 package e2e
 
 import (
+	"bufio"
 	"fmt"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"gotest.tools/assert"
@@ -26,6 +28,23 @@ func expectImageListOutput(t *testing.T, cmd icmd.Cmd, output string) {
 	assert.Equal(t, result.Stdout(), output)
 }
 
+func verifyImageIDListOutput(t *testing.T, cmd icmd.Cmd, count int, distinct int) {
+	cmd.Command = dockerCli.Command("app", "image", "ls", "-q")
+	result := icmd.RunCmd(cmd).Assert(t, icmd.Success)
+	scanner := bufio.NewScanner(strings.NewReader(result.Stdout()))
+	lines := []string{}
+	counter := make(map[string]int)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+		counter[scanner.Text()]++
+	}
+	if err := scanner.Err(); err != nil {
+		assert.Error(t, err, "Verification failed")
+	}
+	assert.Equal(t, len(lines), count)
+	assert.Equal(t, len(counter), distinct)
+}
+
 func TestImageList(t *testing.T) {
 	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
 		cmd := info.configuredCmd
@@ -44,6 +63,16 @@ b-simple-app:latest           simple
 	})
 }
 
+func TestImageListQuiet(t *testing.T) {
+	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
+		cmd := info.configuredCmd
+		dir := fs.NewDir(t, "")
+		defer dir.Remove()
+		insertBundles(t, cmd, info)
+		verifyImageIDListOutput(t, cmd, 3, 2)
+	})
+}
+
 func TestImageRm(t *testing.T) {
 	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
 		cmd := info.configuredCmd

internal/commands/image/list.go

@@ -1,6 +1,7 @@
 package image
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"strings"
@@ -11,10 +12,16 @@ import (
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/config"
 	"github.com/docker/distribution/reference"
+	"github.com/docker/docker/pkg/stringid"
 	"github.com/spf13/cobra"
 )
 
+type imageListOption struct {
+	quiet bool
+}
+
 func listCmd(dockerCli command.Cli) *cobra.Command {
+	options := imageListOption{}
 	cmd := &cobra.Command{
 		Short:   "List application images",
 		Use:     "ls",
@@ -30,14 +37,16 @@ func listCmd(dockerCli command.Cli) *cobra.Command {
 				return err
 			}
 
-			return runList(dockerCli, bundleStore)
+			return runList(dockerCli, options, bundleStore)
 		},
 	}
+	flags := cmd.Flags()
+	flags.BoolVarP(&options.quiet, "quiet", "q", false, "Only show numeric IDs")
 
 	return cmd
 }
 
-func runList(dockerCli command.Cli, bundleStore store.BundleStore) error {
+func runList(dockerCli command.Cli, options imageListOption, bundleStore store.BundleStore) error {
 	bundles, err := bundleStore.List()
 	if err != nil {
 		return err
@@ -48,6 +57,9 @@ func runList(dockerCli command.Cli, bundleStore store.BundleStore) error {
 		return err
 	}
 
+	if options.quiet {
+		return printImageIDs(dockerCli, pkgs)
+	}
 	return printImages(dockerCli, pkgs)
 }
 
@@ -81,6 +93,24 @@ func printImages(dockerCli command.Cli, refs []pkg) error {
 	return w.Flush()
 }
 
+func printImageIDs(dockerCli command.Cli, refs []pkg) error {
+	var buf bytes.Buffer
+
+	for _, ref := range refs {
+		id, ok := ref.ref.(store.ID)
+		if !ok {
+			var err error
+			id, err = store.FromBundle(ref.bundle)
+			if err != nil {
+				return err
+			}
+		}
+		fmt.Fprintln(&buf, stringid.TruncateID(id.String()))
+	}
+	fmt.Fprintf(dockerCli.Out(), buf.String())
+	return nil
+}
+
 func printHeaders(w io.Writer) {
 	var headers []string
 	for _, column := range listColumns {

internal/store/digest.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"regexp"
 
+	"github.com/deislabs/cnab-go/bundle"
 	"github.com/docker/distribution/reference"
 	"github.com/opencontainers/go-digest"
 )
@@ -27,6 +28,11 @@ func FromString(s string) (ID, error) {
 	return ID{s}, nil
 }
 
+func FromBundle(bndle *bundle.Bundle) (ID, error) {
+	digest, err := ComputeDigest(bndle)
+	return ID{digest.Encoded()}, err
+}
+
 // ID is an unique identifier for docker app image bundle, implementing reference.Reference
 type ID struct {
 	digest string