Merge pull request #65447 from wongma7/mapvolume-symlink

Automatic merge from submit-queue (batch tested with PRs 65492, 65516, 65447). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Resolve potential devicePath symlink when MapVolume in containerized kubelet

**What this PR does / why we need it**: Ensures local block volumes will work in case kubelet is running in a container

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #65445

**Special notes for your reviewer**: Code is mostly plumbing. If there is a better way to do it, let me know :)

I assume there will be e2e tests for the non-containerized case. I will need to test the containerized case myself, which may take a while.
**Release note**:

```release-note
NONE
```

pkg/util/mount/exec_mount.go

@@ -140,6 +140,10 @@ func (m *execMounter) ExistsPath(pathname string) (bool, error) {
 	return m.wrappedMounter.ExistsPath(pathname)
 }
 
+func (m *execMounter) EvalHostSymlinks(pathname string) (string, error) {
+	return m.wrappedMounter.EvalHostSymlinks(pathname)
+}
+
 func (m *execMounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {
 	return m.wrappedMounter.PrepareSafeSubpath(subPath)
 }

pkg/util/mount/exec_mount_unsupported.go

@@ -87,6 +87,10 @@ func (mounter *execMounter) ExistsPath(pathname string) (bool, error) {
 	return true, errors.New("not implemented")
 }
 
+func (m *execMounter) EvalHostSymlinks(pathname string) (string, error) {
+	return "", errors.New("not implemented")
+}
+
 func (mounter *execMounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {
 	return subPath.Path, nil, nil
 }

pkg/util/mount/fake.go

@@ -212,6 +212,10 @@ func (f *FakeMounter) ExistsPath(pathname string) (bool, error) {
 	return false, nil
 }
 
+func (f *FakeMounter) EvalHostSymlinks(pathname string) (string, error) {
+	return pathname, nil
+}
+
 func (f *FakeMounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {
 	return subPath.Path, nil, nil
 }

pkg/util/mount/mount.go

@@ -96,6 +96,9 @@ type Interface interface {
 	// Will operate in the host mount namespace if kubelet is running in a container.
 	// Error is returned on any other error than "file not found".
 	ExistsPath(pathname string) (bool, error)
+	// EvalHostSymlinks returns the path name after evaluating symlinks.
+	// Will operate in the host mount namespace if kubelet is running in a container.
+	EvalHostSymlinks(pathname string) (string, error)
 	// CleanSubPaths removes any bind-mounts created by PrepareSafeSubpath in given
 	// pod volume directory.
 	CleanSubPaths(podDir string, volumeName string) error

pkg/util/mount/mount_linux.go

@@ -419,6 +419,10 @@ func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
 	return utilfile.FileExists(pathname)
 }
 
+func (mounter *Mounter) EvalHostSymlinks(pathname string) (string, error) {
+	return filepath.EvalSymlinks(pathname)
+}
+
 // formatAndMount uses unix utils to format and mount the given disk
 func (mounter *SafeFormatAndMount) formatAndMount(source string, target string, fstype string, options []string) error {
 	readOnly := false

pkg/util/mount/mount_unsupported.go

@@ -106,6 +106,10 @@ func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
 	return true, errors.New("not implemented")
 }
 
+func (mounter *Mounter) EvalHostSymlinks(pathname string) (string, error) {
+	return "", unsupportedErr
+}
+
 func (mounter *Mounter) PrepareSafeSubpath(subPath Subpath) (newHostPath string, cleanupAction func(), err error) {
 	return subPath.Path, nil, unsupportedErr
 }

pkg/util/mount/mount_windows.go

@@ -232,6 +232,11 @@ func (mounter *Mounter) ExistsPath(pathname string) (bool, error) {
 	return utilfile.FileExists(pathname)
 }
 
+// EvalHostSymlinks returns the path name after evaluating symlinks
+func (mounter *Mounter) EvalHostSymlinks(pathname string) (string, error) {
+	return filepath.EvalSymlinks(pathname)
+}
+
 // check whether hostPath is within volume path
 // this func will lock all intermediate subpath directories, need to close handle outside of this func after container started
 func lockAndCheckSubPath(volumePath, hostPath string) ([]uintptr, error) {

pkg/util/mount/nsenter_mount.go

@@ -287,6 +287,10 @@ func (mounter *NsenterMounter) ExistsPath(pathname string) (bool, error) {
 	return utilfile.FileExists(kubeletpath)
 }
 
+func (mounter *NsenterMounter) EvalHostSymlinks(pathname string) (string, error) {
+	return mounter.ne.EvalSymlinks(pathname, true)
+}
+
 func (mounter *NsenterMounter) CleanSubPaths(podDir string, volumeName string) error {
 	return doCleanSubPaths(mounter, podDir, volumeName)
 }

pkg/util/mount/nsenter_mount_unsupported.go

@@ -89,6 +89,10 @@ func (*NsenterMounter) ExistsPath(pathname string) (bool, error) {
 	return true, errors.New("not implemented")
 }
 
+func (*NsenterMounter) EvalHostSymlinks(pathname string) (string, error) {
+	return "", errors.New("not implemented")
+}
+
 func (*NsenterMounter) SafeMakeDir(pathname string, base string, perm os.FileMode) error {
 	return nil
 }

pkg/volume/util/operationexecutor/operation_generator.go

@@ -866,6 +866,16 @@ func (og *operationGenerator) GenerateMapVolumeFunc(
 			return volumeToMount.GenerateError("MapVolume failed", fmt.Errorf("Device path of the volume is empty"))
 		}
 
+		// When kubelet is containerized, devicePath may be a symlink at a place unavailable to
+		// kubelet, so evaluate it on the host and expect that it links to a device in /dev,
+		// which will be available to containerized kubelet. If still it does not exist,
+		// AttachFileDevice will fail. If kubelet is not containerized, eval it anyway.
+		mounter := og.GetVolumePluginMgr().Host.GetMounter(blockVolumePlugin.GetPluginName())
+		devicePath, err = mounter.EvalHostSymlinks(devicePath)
+		if err != nil {
+			return volumeToMount.GenerateError("MapVolume.EvalHostSymlinks failed", err)
+		}
+
 		// Map device to global and pod device map path
 		volumeMapPath, volName := blockVolumeMapper.GetPodDeviceMapPath()
 		mapErr = blockVolumeMapper.MapDevice(devicePath, globalMapPath, volumeMapPath, volName, volumeToMount.Pod.UID)