Adds flag modifying pull behavior for running and creating containers

 - Follows the proposal on issue [#34394](moby/moby#34394)
 - Maintains current behavior as default (Pull image if missing)
 - Adds tristate flag allowing modification (PullMissing, PullAlways, PullNever)

Signed-off-by: Zander Mackie <zmackie@gmail.com>

cli/command/container/create.go

@@ -20,10 +20,18 @@ import (
 	"github.com/spf13/pflag"
 )
 
+// Pull constants
+const (
+	PullImageAlways  = "always"
+	PullImageMissing = "missing"
+	PullImageNever   = "never"
+)
+
 type createOptions struct {
 	name      string
 	platform  string
 	untrusted bool
+	pull      string // alway, missing, never
 }
 
 // NewCreateCommand creates a new cobra.Command for `docker create`
@@ -48,6 +56,8 @@ func NewCreateCommand(dockerCli command.Cli) *cobra.Command {
 	flags.SetInterspersed(false)
 
 	flags.StringVar(&opts.name, "name", "", "Assign a name to the container")
+	flags.StringVar(&opts.pull, "pull", PullImageNever,
+		`Pull image before creating ("`+PullImageAlways+`"|"`+PullImageMissing+`"|"`+PullImageNever+`")`)
 
 	// Add an explicit help that doesn't have a `-h` to prevent the conflict
 	// with hostname
@@ -159,6 +169,7 @@ func newCIDFile(path string) (*cidFile, error) {
 	return &cidFile{path: path, file: f}, nil
 }
 
+// nolint: gocyclo
 func createContainer(ctx context.Context, dockerCli command.Cli, containerConfig *containerConfig, opts *createOptions) (*container.ContainerCreateCreatedBody, error) {
 	config := containerConfig.Config
 	hostConfig := containerConfig.HostConfig
@@ -194,31 +205,59 @@ func createContainer(ctx context.Context, dockerCli command.Cli, containerConfig
 	}
 
 	//create the container
-	response, err := dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
+	var response container.ContainerCreateCreatedBody
+	if opts.pull == PullImageMissing { // Pull image only if it does not exist locally. Default.
+		response, err = dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
 
-	//if image not found try to pull it
-	if err != nil {
-		if apiclient.IsErrNotFound(err) && namedRef != nil {
-			fmt.Fprintf(stderr, "Unable to find image '%s' locally\n", reference.FamiliarString(namedRef))
+		//if image not found try to pull it
+		if err != nil {
+			if apiclient.IsErrNotFound(err) && namedRef != nil {
+				fmt.Fprintf(stderr, "Unable to find image '%s' locally\n", reference.FamiliarString(namedRef))
 
-			// we don't want to write to stdout anything apart from container.ID
-			if err := pullImage(ctx, dockerCli, config.Image, opts.platform, stderr); err != nil {
-				return nil, err
-			}
-			if taggedRef, ok := namedRef.(reference.NamedTagged); ok && trustedRef != nil {
-				if err := image.TagTrusted(ctx, dockerCli, trustedRef, taggedRef); err != nil {
+				// we don't want to write to stdout anything apart from container.ID
+				if err := pullImage(ctx, dockerCli, config.Image, opts.platform, stderr); err != nil {
 					return nil, err
 				}
+				if taggedRef, ok := namedRef.(reference.NamedTagged); ok && trustedRef != nil {
+					if err := image.TagTrusted(ctx, dockerCli, trustedRef, taggedRef); err != nil {
+						return nil, err
+					}
+				}
+				// Retry
+				var retryErr error
+				response, retryErr = dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
+				if retryErr != nil {
+					return nil, retryErr
+				}
+			} else {
+				return nil, err
 			}
-			// Retry
-			var retryErr error
-			response, retryErr = dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
-			if retryErr != nil {
-				return nil, retryErr
+		}
+
+	} else if opts.pull == PullImageAlways { // Always try and pull the image.
+		if err := pullImage(ctx, dockerCli, config.Image, opts.platform, stderr); err != nil {
+			return nil, err
+		}
+		if taggedRef, ok := namedRef.(reference.NamedTagged); ok && trustedRef != nil {
+			if err := image.TagTrusted(ctx, dockerCli, trustedRef, taggedRef); err != nil {
+				return nil, err
 			}
-		} else {
+		}
+		response, err = dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
+		if err != nil {
 			return nil, err
 		}
+
+	} else if opts.pull == PullImageNever { // Never try and pull the image
+		response, err = dockerCli.Client().ContainerCreate(ctx, config, hostConfig, networkingConfig, opts.name)
+
+		if err != nil {
+			if apiclient.IsErrNotFound(err) && namedRef != nil {
+				fmt.Fprintf(stderr, "Unable to find image '%s' locally\nWill not pull due to '%s'", reference.FamiliarString(namedRef), opts.pull)
+			}
+		}
+	} else { // We got something weird
+		return nil, errors.Errorf("Unknown pull option : %s", opts.pull)
 	}
 
 	for _, warning := range response.Warnings {

cli/command/container/create_test.go

@@ -113,6 +113,7 @@ func TestCreateContainerPullsImageIfMissing(t *testing.T) {
 		name:      "name",
 		platform:  runtime.GOOS,
 		untrusted: true,
+		pull:      PullImageMissing,
 	})
 	assert.NilError(t, err)
 	expected := container.ContainerCreateCreatedBody{ID: containerID}
@@ -121,6 +122,52 @@ func TestCreateContainerPullsImageIfMissing(t *testing.T) {
 	assert.Check(t, is.Contains(stderr, "Unable to find image 'does-not-exist-locally:latest' locally"))
 }
 
+func TestCreateContainerNeverPullsImage(t *testing.T) {
+	imageName := "does-not-exist-locally"
+	responseCounter := 0
+
+	client := &fakeClient{
+		createContainerFunc: func(
+			config *container.Config,
+			hostConfig *container.HostConfig,
+			networkingConfig *network.NetworkingConfig,
+			containerName string,
+		) (container.ContainerCreateCreatedBody, error) {
+			defer func() { responseCounter++ }()
+			switch responseCounter {
+			case 0:
+				return container.ContainerCreateCreatedBody{}, fakeNotFound{}
+			default:
+				return container.ContainerCreateCreatedBody{}, errors.New("unexpected")
+			}
+		},
+		imageCreateFunc: func(parentReference string, options types.ImageCreateOptions) (io.ReadCloser, error) {
+			return ioutil.NopCloser(strings.NewReader("")), nil
+		},
+		infoFunc: func() (types.Info, error) {
+			return types.Info{IndexServerAddress: "http://indexserver"}, nil
+		},
+	}
+	cli := test.NewFakeCli(client)
+	config := &containerConfig{
+		Config: &container.Config{
+			Image: imageName,
+		},
+		HostConfig: &container.HostConfig{},
+	}
+	body, err := createContainer(context.Background(), cli, config, &createOptions{
+		name:      "name",
+		platform:  runtime.GOOS,
+		untrusted: true,
+		pull:      PullImageNever,
+	})
+	assert.NilError(t, err)
+	expected := container.ContainerCreateCreatedBody{}
+	assert.Check(t, is.DeepEqual(expected, *body))
+	stderr := cli.ErrBuffer().String()
+	assert.Check(t, is.Contains(stderr, "Unable to find image 'does-not-exist-locally:latest' locally"))
+}
+
 func TestNewCreateCommandWithContentTrustErrors(t *testing.T) {
 	testCases := []struct {
 		name          string

cli/command/container/run.go

@@ -57,6 +57,8 @@ func NewRunCommand(dockerCli command.Cli) *cobra.Command {
 	flags.BoolVar(&opts.sigProxy, "sig-proxy", true, "Proxy received signals to the process")
 	flags.StringVar(&opts.name, "name", "", "Assign a name to the container")
 	flags.StringVar(&opts.detachKeys, "detach-keys", "", "Override the key sequence for detaching a container")
+	flags.StringVar(&opts.createOptions.pull, "pull", PullImageNever,
+		`Pull image before running ("`+PullImageAlways+`"|"`+PullImageMissing+`"|"`+PullImageNever+`")`)
 
 	// Add an explicit help that doesn't have a `-h` to prevent the conflict
 	// with hostname