Allow subPath within volumeMounts.

docs/spec/spec.md

@@ -428,5 +428,6 @@ container: # v1.Container
     - name: ... # This must match a name from Volumes
       mountPath: ... # Where to mount the named Volume.
       readOnly: ... # Must be True, will default to True, so it may be omitted.
+      subPath: ...
   workingDir: ... # Optional
 ```

pkg/apis/serving/fieldmask.go

@@ -156,10 +156,10 @@ func VolumeMountMask(in *corev1.VolumeMount) *corev1.VolumeMount {
 	out.Name = in.Name
 	out.ReadOnly = in.ReadOnly
 	out.MountPath = in.MountPath
+	out.SubPath = in.SubPath
 
 	// Disallowed fields
 	// This list is unnecessary, but added here for clarity
-	out.SubPath = ""
 	out.MountPropagation = nil
 
 	return out

pkg/apis/serving/fieldmask_test.go

@@ -190,12 +190,13 @@ func TestVolumeMountMask(t *testing.T) {
 		Name:      "foo",
 		ReadOnly:  true,
 		MountPath: "/foo/bar",
+		SubPath:   "baz",
 	}
 	in := &corev1.VolumeMount{
 		Name:             "foo",
 		ReadOnly:         true,
 		MountPath:        "/foo/bar",
-		SubPath:          "baz/",
+		SubPath:          "baz",
 		MountPropagation: &mode,
 	}
 

pkg/apis/serving/k8s_validation_test.go

@@ -379,7 +379,6 @@ func TestContainerValidation(t *testing.T) {
 		}).ViaFieldIndex("volumeMounts", 0).Also(
 			apis.ErrMissingField("readOnly").ViaFieldIndex("volumeMounts", 0)).Also(
 			apis.ErrMissingField("mountPath").ViaFieldIndex("volumeMounts", 0)).Also(
-			apis.ErrDisallowedFields("subPath").ViaFieldIndex("volumeMounts", 0)).Also(
 			apis.ErrDisallowedFields("mountPropagation").ViaFieldIndex("volumeMounts", 0)),
 	}, {
 		name: "missing known volumeMounts",

test/conformance/volumes_test.go

@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/knative/serving/pkg/apis/serving/v1alpha1"
 	. "github.com/knative/serving/pkg/reconciler/testing"
 	"github.com/knative/serving/test"
 
@@ -129,15 +130,19 @@ func TestSecretVolume(t *testing.T) {
 	defer cleanup()
 	test.CleanupOnInterrupt(cleanup)
 
-	withVolume := WithVolume("asdf", filepath.Dir(test.HelloVolumePath), corev1.VolumeSource{
+	withVolume := WithVolume("asdf", "overwritten below", corev1.VolumeSource{
 		Secret: &corev1.SecretVolumeSource{
 			SecretName: secret.Name,
 		},
 	})
+	withSubpath := func(svc *v1alpha1.Service) {
+		vm := &svc.Spec.Template.Spec.Containers[0].VolumeMounts[0]
+		vm.MountPath = test.HelloVolumePath
+		vm.SubPath = filepath.Base(test.HelloVolumePath)
+	}
 
 	// Setup initial Service
-	if _, err := test.CreateRunLatestServiceReady(t, clients, &names, &test.Options{}, withVolume); err != nil {
-
+	if _, err := test.CreateRunLatestServiceReady(t, clients, &names, &test.Options{}, withVolume, withSubpath); err != nil {
 		t.Fatalf("Failed to create initial Service %v: %v", names.Service, err)
 	}
 

test/test_images/hellovolume/service.yaml

@@ -26,7 +26,8 @@ spec:
         image: github.com/knative/serving/test/test_images/hellovolume
         volumeMounts:
         - name: foo
-          mountPath: /hello
+          mountPath: /hello/world
+          subPath: world
       volumes:
       - name: foo
         secret: