Few stack deploy network fixes

- Make sure we use the correct network name for external ones.
- Make the default network overridable and only creates networks that
  are used by services — so that default network is only created if a
  service doesn't declare a network.

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

command/stack/deploy.go

@@ -117,7 +117,9 @@ func deployCompose(ctx context.Context, dockerCli *command.DockerCli, opts deplo
 
 	namespace := convert.NewNamespace(opts.namespace)
 
-	networks, externalNetworks := convert.Networks(namespace, config.Networks)
+	serviceNetworks := getServicesDeclaredNetworks(config.Services)
+
+	networks, externalNetworks := convert.Networks(namespace, config.Networks, serviceNetworks)
 	if err := validateExternalNetworks(ctx, dockerCli, externalNetworks); err != nil {
 		return err
 	}
@@ -131,6 +133,20 @@ func deployCompose(ctx context.Context, dockerCli *command.DockerCli, opts deplo
 	return deployServices(ctx, dockerCli, services, namespace, opts.sendRegistryAuth)
 }
 
+func getServicesDeclaredNetworks(serviceConfigs []composetypes.ServiceConfig) map[string]struct{} {
+	serviceNetworks := map[string]struct{}{}
+	for _, serviceConfig := range serviceConfigs {
+		if len(serviceConfig.Networks) == 0 {
+			serviceNetworks["default"] = struct{}{}
+			continue
+		}
+		for network := range serviceConfig.Networks {
+			serviceNetworks[network] = struct{}{}
+		}
+	}
+	return serviceNetworks
+}
+
 func propertyWarnings(properties map[string]string) string {
 	var msgs []string
 	for name, description := range properties {

compose/convert/compose.go

@@ -43,20 +43,15 @@ func AddStackLabel(namespace Namespace, labels map[string]string) map[string]str
 type networkMap map[string]composetypes.NetworkConfig
 
 // Networks from the compose-file type to the engine API type
-func Networks(namespace Namespace, networks networkMap) (map[string]types.NetworkCreate, []string) {
+func Networks(namespace Namespace, networks networkMap, servicesNetworks map[string]struct{}) (map[string]types.NetworkCreate, []string) {
 	if networks == nil {
 		networks = make(map[string]composetypes.NetworkConfig)
 	}
 
-	// TODO: only add default network if it's used
-	if _, ok := networks["default"]; !ok {
-		networks["default"] = composetypes.NetworkConfig{}
-	}
-
 	externalNetworks := []string{}
 	result := make(map[string]types.NetworkCreate)
-
+	for internalName := range servicesNetworks {
-	for internalName, network := range networks {
+		network := networks[internalName]
 		if network.External.External {
 			externalNetworks = append(externalNetworks, network.External.Name)
 			continue

compose/convert/compose_test.go

@@ -28,6 +28,11 @@ func TestAddStackLabel(t *testing.T) {
 
 func TestNetworks(t *testing.T) {
 	namespace := Namespace{name: "foo"}
+	serviceNetworks := map[string]struct{}{
+		"normal":  {},
+		"outside": {},
+		"default": {},
+	}
 	source := networkMap{
 		"normal": composetypes.NetworkConfig{
 			Driver: "overlay",
@@ -79,7 +84,7 @@ func TestNetworks(t *testing.T) {
 		},
 	}
 
-	networks, externals := Networks(namespace, source)
+	networks, externals := Networks(namespace, source, serviceNetworks)
 	assert.DeepEqual(t, networks, expected)
 	assert.DeepEqual(t, externals, []string{"special"})
 }