Add compose support of attachable in networks

This fix tries to address the issue raised in 29975 where
it was not possible to specify `attachable` flag for networks
in compose format.

NOTE: Compose format aleady supports `labels` in networks.

This fix adds the support of `attachable` for compose v3.1 format.

Additiona unit tests have been updated and added.

This fix fixes 29975.

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

compose/convert/compose.go

@@ -61,10 +61,11 @@ func Networks(namespace Namespace, networks networkMap, servicesNetworks map[str
 		}
 
 		createOpts := types.NetworkCreate{
-			Labels:   AddStackLabel(namespace, network.Labels),
-			Driver:   network.Driver,
-			Options:  network.DriverOpts,
-			Internal: network.Internal,
+			Labels:     AddStackLabel(namespace, network.Labels),
+			Driver:     network.Driver,
+			Options:    network.DriverOpts,
+			Internal:   network.Internal,
+			Attachable: network.Attachable,
 		}
 
 		if network.Ipam.Driver != "" || len(network.Ipam.Config) > 0 {

compose/convert/compose_test.go

@@ -30,9 +30,10 @@ func TestAddStackLabel(t *testing.T) {
 func TestNetworks(t *testing.T) {
 	namespace := Namespace{name: "foo"}
 	serviceNetworks := map[string]struct{}{
-		"normal":  {},
-		"outside": {},
-		"default": {},
+		"normal":        {},
+		"outside":       {},
+		"default":       {},
+		"attachablenet": {},
 	}
 	source := networkMap{
 		"normal": composetypes.NetworkConfig{
@@ -58,6 +59,10 @@ func TestNetworks(t *testing.T) {
 				Name:     "special",
 			},
 		},
+		"attachablenet": composetypes.NetworkConfig{
+			Driver:     "overlay",
+			Attachable: true,
+		},
 	}
 	expected := map[string]types.NetworkCreate{
 		"default": {
@@ -83,6 +88,13 @@ func TestNetworks(t *testing.T) {
 				"something":    "labeled",
 			},
 		},
+		"attachablenet": {
+			Driver:     "overlay",
+			Attachable: true,
+			Labels: map[string]string{
+				LabelNamespace: "foo",
+			},
+		},
 	}
 
 	networks, externals := Networks(namespace, source, serviceNetworks)