Add "--service-images" to pull command

This allows users in a single node configuration to optionally pull
down the service images defined in an app bundle with:

 docker app pull --service-images [your app]

Fixes: fixes #789

Signed-off-by: Andy Doan <andy@foundries.io>

Author: doanac

e2e/pushpull_test.go

@@ -107,6 +107,28 @@ Unable to find App "unknown": failed to resolve bundle manifest "docker.io/libra
 	})
 }
 
+func TestPushPullServiceImages(t *testing.T) {
+	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
+		cmd := info.configuredCmd
+		ref := info.registryAddress + "/test/push-pull"
+		tag := ":v.0.0.1"
+		build(t, cmd, dockerCli, ref+tag, filepath.Join("testdata", "push-pull"))
+
+		cmd.Command = dockerCli.Command("app", "push", ref+tag)
+		icmd.RunCmd(cmd).Assert(t, icmd.Success)
+
+		// Make sure this image does not exist so that we can verify the pull works.
+		cmd.Command = dockerCli.Command("image", "rm", "busybox:1.30.1")
+		icmd.RunCmd(cmd).Assert(t, icmd.Success)
+
+		cmd.Command = dockerCli.Command("app", "pull", "--service-images", ref+tag)
+		icmd.RunCmd(cmd).Assert(t, icmd.Success)
+
+		cmd.Command = dockerCli.Command("image", "inspect", "busybox@sha256:4b6ad3a68d34da29bf7c8ccb5d355ba8b4babcad1f99798204e7abb43e54ee3d")
+		icmd.RunCmd(cmd).Assert(t, icmd.Success)
+	})
+}
+
 func TestPushInstallBundle(t *testing.T) {
 	runWithDindSwarmAndRegistry(t, func(info dindSwarmAndRegistryInfo) {
 		cmd := info.configuredCmd

internal/commands/pull.go

@@ -1,34 +1,73 @@
 package commands
 
 import (
+	"context"
 	"fmt"
 	"os"
 
+	"github.com/docker/docker/api/types"
 	"github.com/docker/app/internal/cnab"
 	"github.com/docker/app/internal/packager"
 	"github.com/docker/app/internal/store"
 	"github.com/docker/cli/cli"
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/config"
 	"github.com/docker/distribution/reference"
+	"github.com/docker/docker/pkg/jsonmessage"
+	"github.com/docker/docker/registry"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 )
 
+type pullOptions struct {
+	serviceImages bool
+}
+
 func pullCmd(dockerCli command.Cli) *cobra.Command {
+	var opts pullOptions
+
 	cmd := &cobra.Command{
 		Use:     "pull APP_IMAGE",
 		Short:   "Pull an App image from a registry",
 		Example: `$ docker app pull myrepo/myapp:0.1.0`,
 		Args:    cli.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return runPull(dockerCli, args[0])
+			return runPull(dockerCli, opts, args[0])
 		},
 	}
+	cmd.Flags().BoolVar(&opts.serviceImages, "service-images", false, "Also pull down service images to this host's context")
 	return cmd
 }
 
-func runPull(dockerCli command.Cli, name string) error {
+func pullImage(ctx context.Context, cli command.Cli, image string) error {
+	ref, err := reference.ParseNormalizedNamed(image)
+	if err != nil {
+		return err
+	}
+
+	// Resolve the Repository name from fqn to RepositoryInfo
+	repoInfo, err := registry.ParseRepositoryInfo(ref)
+	if err != nil {
+		return err
+	}
+	authConfig := command.ResolveAuthConfig(ctx, cli, repoInfo.Index)
+	encodedAuth, err := command.EncodeAuthToBase64(authConfig)
+	if err != nil {
+		return err
+	}
+	options := types.ImagePullOptions{
+		RegistryAuth: encodedAuth,
+	}
+	responseBody, err := cli.Client().ImagePull(ctx, image, options)
+	if err != nil {
+		return err
+	}
+	defer responseBody.Close()
+
+	return jsonmessage.DisplayJSONMessagesStream(responseBody, cli.Out(), cli.Out().FD(), false, nil)
+}
+
+func runPull(dockerCli command.Cli, opts pullOptions, name string) error {
 	appstore, err := store.NewApplicationStore(config.Dir())
 	if err != nil {
 		return err
@@ -52,5 +91,13 @@ func runPull(dockerCli command.Cli, name string) error {
 	}
 	fmt.Fprintf(os.Stdout, "Successfully pulled %q (%s) from %s\n", bndl.Name, bndl.Version, ref.String())
 
+	if opts.serviceImages {
+		ctx := context.Background()
+		for name, image := range bndl.Images {
+			fmt.Fprintf(os.Stdout, "Pulling: %s -> %s\n", name, image.Image)
+			pullImage(ctx, dockerCli, image.Image)
+		}
+	}
+
 	return nil
 }