Add support for volume Subpath option

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

pkg/compose/create.go

@@ -1137,6 +1137,7 @@ func buildVolumeOptions(vol *types.ServiceVolumeVolume) *mount.VolumeOptions {
 	}
 	return &mount.VolumeOptions{
 		NoCopy:  vol.NoCopy,
+		Subpath: vol.Subpath,
 		// Labels:       , // FIXME missing from model ?
 		// DriverConfig: , // FIXME missing from model ?
 	}

pkg/compose/create_test.go

@@ -113,6 +113,14 @@ func TestBuildContainerMountOptions(t *testing.T) {
 						Type:   composetypes.VolumeTypeVolume,
 						Target: "/var/myvolume2",
 					},
+					{
+						Type:   composetypes.VolumeTypeVolume,
+						Source: "myVolume3",
+						Target: "/var/myvolume3",
+						Volume: &composetypes.ServiceVolumeVolume{
+							Subpath: "etc",
+						},
+					},
 					{
 						Type:   composetypes.VolumeTypeNamedPipe,
 						Source: "\\\\.\\pipe\\docker_engine_windows",
@@ -149,20 +157,24 @@ func TestBuildContainerMountOptions(t *testing.T) {
 		return mounts[i].Target < mounts[j].Target
 	})
 	assert.NilError(t, err)
-	assert.Assert(t, len(mounts) == 3)
+	assert.Assert(t, len(mounts) == 4)
 	assert.Equal(t, mounts[0].Target, "/var/myvolume1")
 	assert.Equal(t, mounts[1].Target, "/var/myvolume2")
-	assert.Equal(t, mounts[2].Target, "\\\\.\\pipe\\docker_engine")
+	assert.Equal(t, mounts[2].Target, "/var/myvolume3")
+	assert.Equal(t, mounts[2].VolumeOptions.Subpath, "etc")
+	assert.Equal(t, mounts[3].Target, "\\\\.\\pipe\\docker_engine")
 
 	mounts, err = buildContainerMountOptions(project, project.Services["myService"], moby.ImageInspect{}, inherit)
 	sort.Slice(mounts, func(i, j int) bool {
 		return mounts[i].Target < mounts[j].Target
 	})
 	assert.NilError(t, err)
-	assert.Assert(t, len(mounts) == 3)
+	assert.Assert(t, len(mounts) == 4)
 	assert.Equal(t, mounts[0].Target, "/var/myvolume1")
 	assert.Equal(t, mounts[1].Target, "/var/myvolume2")
-	assert.Equal(t, mounts[2].Target, "\\\\.\\pipe\\docker_engine")
+	assert.Equal(t, mounts[2].Target, "/var/myvolume3")
+	assert.Equal(t, mounts[2].VolumeOptions.Subpath, "etc")
+	assert.Equal(t, mounts[3].Target, "\\\\.\\pipe\\docker_engine")
 }
 
 func TestDefaultNetworkSettings(t *testing.T) {