Allow AWS EBS volumes to be attached as ReadOnly.

pkg/cloudprovider/providers/aws/aws.go

@@ -429,7 +429,7 @@ type Volumes interface {
 	// Attach the disk to the node with the specified NodeName
 	// nodeName can be empty to mean "the instance on which we are running"
 	// Returns the device (e.g. /dev/xvdf) where we attached the volume
-	AttachDisk(diskName KubernetesVolumeID, nodeName types.NodeName, readOnly bool) (string, error)
+	AttachDisk(diskName KubernetesVolumeID, nodeName types.NodeName) (string, error)
 	// Detach the disk from the node with the specified NodeName
 	// nodeName can be empty to mean "the instance on which we are running"
 	// Returns the device where the volume was attached
@@ -1956,7 +1956,7 @@ func wrapAttachError(err error, disk *awsDisk, instance string) error {
 }
 
 // AttachDisk implements Volumes.AttachDisk
-func (c *Cloud) AttachDisk(diskName KubernetesVolumeID, nodeName types.NodeName, readOnly bool) (string, error) {
+func (c *Cloud) AttachDisk(diskName KubernetesVolumeID, nodeName types.NodeName) (string, error) {
 	disk, err := newAWSDisk(c, diskName)
 	if err != nil {
 		return "", err
@@ -1967,12 +1967,6 @@ func (c *Cloud) AttachDisk(diskName KubernetesVolumeID, nodeName types.NodeName,
 		return "", fmt.Errorf("error finding instance %s: %q", nodeName, err)
 	}
 
-	if readOnly {
-		// TODO: We could enforce this when we mount the volume (?)
-		// TODO: We could also snapshot the volume and attach copies of it
-		return "", errors.New("AWS volumes cannot be mounted read-only")
-	}
-
 	// mountDevice will hold the device where we should try to attach the disk
 	var mountDevice mountDevice
 	// alreadyAttached is true if we have already called AttachVolume on this disk

pkg/volume/aws_ebs/attacher.go

@@ -59,7 +59,7 @@ func (plugin *awsElasticBlockStorePlugin) GetDeviceMountRefs(deviceMountPath str
 }
 
 func (attacher *awsElasticBlockStoreAttacher) Attach(spec *volume.Spec, nodeName types.NodeName) (string, error) {
-	volumeSource, readOnly, err := getVolumeSource(spec)
+	volumeSource, _, err := getVolumeSource(spec)
 	if err != nil {
 		return "", err
 	}
@@ -68,7 +68,7 @@ func (attacher *awsElasticBlockStoreAttacher) Attach(spec *volume.Spec, nodeName
 
 	// awsCloud.AttachDisk checks if disk is already attached to node and
 	// succeeds in that case, so no need to do that separately.
-	devicePath, err := attacher.awsVolumes.AttachDisk(volumeID, nodeName, readOnly)
+	devicePath, err := attacher.awsVolumes.AttachDisk(volumeID, nodeName)
 	if err != nil {
 		glog.Errorf("Error attaching volume %q to node %q: %+v", volumeID, nodeName, err)
 		return "", err

pkg/volume/aws_ebs/attacher_test.go

@@ -76,15 +76,14 @@ type testcase struct {
 func TestAttachDetach(t *testing.T) {
 	diskName := aws.KubernetesVolumeID("disk")
 	nodeName := types.NodeName("instance")
-	readOnly := false
-	spec := createVolSpec(diskName, readOnly)
+	spec := createVolSpec(diskName, false)
 	attachError := errors.New("Fake attach error")
 	detachError := errors.New("Fake detach error")
 	tests := []testcase{
 		// Successful Attach call
 		{
 			name:   "Attach_Positive",
-			attach: attachCall{diskName, nodeName, readOnly, "/dev/sda", nil},
+			attach: attachCall{diskName, nodeName, "/dev/sda", nil},
 			test: func(testcase *testcase) (string, error) {
 				attacher := newAttacher(testcase)
 				return attacher.Attach(spec, nodeName)
@@ -95,7 +94,7 @@ func TestAttachDetach(t *testing.T) {
 		// Attach call fails
 		{
 			name:   "Attach_Negative",
-			attach: attachCall{diskName, nodeName, readOnly, "", attachError},
+			attach: attachCall{diskName, nodeName, "", attachError},
 			test: func(testcase *testcase) (string, error) {
 				attacher := newAttacher(testcase)
 				return attacher.Attach(spec, nodeName)
@@ -195,7 +194,6 @@ func createPVSpec(name aws.KubernetesVolumeID, readOnly bool) *volume.Spec {
 type attachCall struct {
 	diskName      aws.KubernetesVolumeID
 	nodeName      types.NodeName
-	readOnly      bool
 	retDeviceName string
 	ret           error
 }
@@ -214,7 +212,7 @@ type diskIsAttachedCall struct {
 	ret        error
 }
 
-func (testcase *testcase) AttachDisk(diskName aws.KubernetesVolumeID, nodeName types.NodeName, readOnly bool) (string, error) {
+func (testcase *testcase) AttachDisk(diskName aws.KubernetesVolumeID, nodeName types.NodeName) (string, error) {
 	expected := &testcase.attach
 
 	if expected.diskName == "" && expected.nodeName == "" {
@@ -234,12 +232,7 @@ func (testcase *testcase) AttachDisk(diskName aws.KubernetesVolumeID, nodeName t
 		return "", errors.New("Unexpected AttachDisk call: wrong nodeName")
 	}
 
-	if expected.readOnly != readOnly {
-		testcase.t.Errorf("Unexpected AttachDisk call: expected readOnly %v, got %v", expected.readOnly, readOnly)
-		return "", errors.New("Unexpected AttachDisk call: wrong readOnly")
-	}
-
-	glog.V(4).Infof("AttachDisk call: %s, %s, %v, returning %q, %v", diskName, nodeName, readOnly, expected.retDeviceName, expected.ret)
+	glog.V(4).Infof("AttachDisk call: %s, %s, returning %q, %v", diskName, nodeName, expected.retDeviceName, expected.ret)
 
 	return expected.retDeviceName, expected.ret
 }

plugin/pkg/admission/storage/persistentvolume/label/admission_test.go

@@ -36,7 +36,7 @@ type mockVolumes struct {
 
 var _ aws.Volumes = &mockVolumes{}
 
-func (v *mockVolumes) AttachDisk(diskName aws.KubernetesVolumeID, nodeName types.NodeName, readOnly bool) (string, error) {
+func (v *mockVolumes) AttachDisk(diskName aws.KubernetesVolumeID, nodeName types.NodeName) (string, error) {
 	return "", fmt.Errorf("not implemented")
 }