@@ -37,7 +37,7 @@ func getServices(

 		types.ServiceListOptions{Filters: getStackFilter(namespace)})

 }

-func getNetworks(

+func getStackNetworks(

 	ctx context.Context,

 	apiclient client.APIClient,

 	namespace string,

@@ -22,6 +22,7 @@ import (

 	"github.com/docker/docker/cli"

 	"github.com/docker/docker/cli/command"

 	servicecmd "github.com/docker/docker/cli/command/service"

+	dockerclient "github.com/docker/docker/client"

 	"github.com/docker/docker/opts"

 	runconfigopts "github.com/docker/docker/runconfig/opts"

 	"github.com/docker/go-connections/nat"

@@ -123,7 +124,10 @@ func deployCompose(ctx context.Context, dockerCli *command.DockerCli, opts deplo

 	namespace := namespace{name: opts.namespace}

-	networks := convertNetworks(namespace, config.Networks)

+	networks, externalNetworks := convertNetworks(namespace, config.Networks)

+	if err := validateExternalNetworks(ctx, dockerCli, externalNetworks); err != nil {

+		return err

+	}

 	if err := createNetworks(ctx, dockerCli, namespace, networks); err != nil {

 		return err

 	}

@@ -179,7 +183,7 @@ func getConfigFile(filename string) (*composetypes.ConfigFile, error) {

 func convertNetworks(

 	namespace namespace,

 	networks map[string]composetypes.NetworkConfig,

-) map[string]types.NetworkCreate {

+) (map[string]types.NetworkCreate, []string) {

 	if networks == nil {

 		networks = make(map[string]composetypes.NetworkConfig)

 	}

@@ -187,10 +191,12 @@ func convertNetworks(

 	// TODO: only add default network if it's used

 	networks["default"] = composetypes.NetworkConfig{}

+	externalNetworks := []string{}

 	result := make(map[string]types.NetworkCreate)

 	for internalName, network := range networks {

-		if network.External.Name != "" {

+		if network.External.External {

+			externalNetworks = append(externalNetworks, network.External.Name)

 			continue

 		}

@@ -216,7 +222,29 @@ func convertNetworks(

 		result[internalName] = createOpts

 	}

-	return result

+	return result, externalNetworks

+}

+

+func validateExternalNetworks(

+	ctx context.Context,

+	dockerCli *command.DockerCli,

+	externalNetworks []string) error {

+	client := dockerCli.Client()

+

+	for _, networkName := range externalNetworks {

+		network, err := client.NetworkInspect(ctx, networkName)

+		if err != nil {

+			if dockerclient.IsErrNetworkNotFound(err) {

+				return fmt.Errorf("network %q is declared as external, but could not be found. You need to create the network before the stack is deployed (with overlay driver)", networkName)

+			}

+			return err

+		}

+		if network.Scope != "swarm" {

+			return fmt.Errorf("network %q is declared as external, but it is not in the right scope: %q instead of %q", networkName, network.Scope, "swarm")

+		}

+	}

+

+	return nil

 }

 func createNetworks(

@@ -227,7 +255,7 @@ func createNetworks(

 ) error {

 	client := dockerCli.Client()

-	existingNetworks, err := getNetworks(ctx, client, namespace.name)

+	existingNetworks, err := getStackNetworks(ctx, client, namespace.name)

 	if err != nil {

 		return err

 	}

@@ -258,30 +286,39 @@ func createNetworks(

 func convertServiceNetworks(

 	networks map[string]*composetypes.ServiceNetworkConfig,

+	networkConfigs map[string]composetypes.NetworkConfig,

 	namespace namespace,

 	name string,

-) []swarm.NetworkAttachmentConfig {

+) ([]swarm.NetworkAttachmentConfig, error) {

 	if len(networks) == 0 {

 		return []swarm.NetworkAttachmentConfig{

 			{

 				Target:  namespace.scope("default"),

 				Aliases: []string{name},

 			},

-		}

+		}, nil

 	}

 	nets := []swarm.NetworkAttachmentConfig{}

 	for networkName, network := range networks {

+		networkConfig, ok := networkConfigs[networkName]

+		if !ok {

+			return []swarm.NetworkAttachmentConfig{}, fmt.Errorf("invalid network: %s", networkName)

+		}

 		var aliases []string

 		if network != nil {

 			aliases = network.Aliases

 		}

+		target := namespace.scope(networkName)

+		if networkConfig.External.External {

+			target = networkName

+		}

 		nets = append(nets, swarm.NetworkAttachmentConfig{

-			Target:  namespace.scope(networkName),

+			Target:  target,

 			Aliases: append(aliases, name),

 		})

 	}

-	return nets

+	return nets, nil

 }

 func convertVolumes(

@@ -472,9 +509,10 @@ func convertServices(

 	services := config.Services

 	volumes := config.Volumes

+	networks := config.Networks

 	for _, service := range services {

-		serviceSpec, err := convertService(namespace, service, volumes)

+		serviceSpec, err := convertService(namespace, service, networks, volumes)

 		if err != nil {

 			return nil, err

 		}

@@ -487,6 +525,7 @@ func convertServices(

 func convertService(

 	namespace namespace,

 	service composetypes.ServiceConfig,

+	networkConfigs map[string]composetypes.NetworkConfig,

 	volumes map[string]composetypes.VolumeConfig,

 ) (swarm.ServiceSpec, error) {

 	name := namespace.scope(service.Name)

@@ -523,6 +562,11 @@ func convertService(

 		return swarm.ServiceSpec{}, err

 	}

+	networks, err := convertServiceNetworks(service.Networks, networkConfigs, namespace, service.Name)

+	if err != nil {

+		return swarm.ServiceSpec{}, err

+	}

+

 	serviceSpec := swarm.ServiceSpec{

 		Annotations: swarm.Annotations{

 			Name:   name,

@@ -553,7 +597,7 @@ func convertService(

 		},

 		EndpointSpec: endpoint,

 		Mode:         mode,

-		Networks:     convertServiceNetworks(service.Networks, namespace, service.Name),

+		Networks:     networks,

 		UpdateConfig: convertUpdateConfig(service.Deploy.UpdateConfig),

 	}

@@ -49,7 +49,7 @@ func runRemove(dockerCli *command.DockerCli, opts removeOptions) error {

 		}

 	}

-	networks, err := getNetworks(ctx, client, namespace)

+	networks, err := getStackNetworks(ctx, client, namespace)

 	if err != nil {

 		return err

 	}