kubeadm: throw errors on unmount instead of warnings

Instead of warnings when syscall.Unmount() causes errors,
store all the errors in an aggregate. Abort the reset operation if
at least one unmount error was encountered.

cmd/kubeadm/app/cmd/phases/reset/cleanupnode.go

@@ -84,11 +84,15 @@ func runCleanupNode(c workflow.RunData) error {
 		// Try to unmount mounted directories under kubeadmconstants.KubeletRunDirectory in order to be able to remove the kubeadmconstants.KubeletRunDirectory directory later
 		fmt.Printf("[reset] Unmounting mounted directories in %q\n", kubeadmconstants.KubeletRunDirectory)
 		// In case KubeletRunDirectory holds a symbolic link, evaluate it
-		kubeletRunDir, err := absoluteKubeletRunDirectory()
+		kubeletRunDirectory, err := absoluteKubeletRunDirectory()
-		if err == nil {
+		if err != nil {
-			// Only clean absoluteKubeletRunDirectory if umountDirsCmd passed without error
+			return err
-			dirsToClean = append(dirsToClean, kubeletRunDir)
 		}
+		// Unmount all mount paths under kubeletRunDirectory
+		if err := unmountKubeletDirectory(kubeletRunDirectory); err != nil {
+			return err
+		}
+		dirsToClean = append(dirsToClean, kubeletRunDirectory)
 	} else {
 		fmt.Printf("[reset] Would unmount mounted directories in %q\n", kubeadmconstants.KubeletRunDirectory)
 	}
@@ -131,13 +135,7 @@ func runCleanupNode(c workflow.RunData) error {
 func absoluteKubeletRunDirectory() (string, error) {
 	absoluteKubeletRunDirectory, err := filepath.EvalSymlinks(kubeadmconstants.KubeletRunDirectory)
 	if err != nil {
-		klog.Warningf("[reset] Failed to evaluate the %q directory. Skipping its unmount and cleanup: %v\n", kubeadmconstants.KubeletRunDirectory, err)
+		return "", errors.Wrapf(err, "failed to evaluate the %q directory", kubeadmconstants.KubeletRunDirectory)
-		return "", err
-	}
-	err = unmountKubeletDirectory(absoluteKubeletRunDirectory)
-	if err != nil {
-		klog.Warningf("[reset] Failed to unmount mounted directories in %s \n", kubeadmconstants.KubeletRunDirectory)
-		return "", err
 	}
 	return absoluteKubeletRunDirectory, nil
 }

cmd/kubeadm/app/cmd/phases/reset/unmount.go

@@ -24,7 +24,7 @@ import (
 )
 
 // unmountKubeletDirectory is a NOOP on all but linux.
-func unmountKubeletDirectory(absoluteKubeletRunDirectory string) error {
+func unmountKubeletDirectory(kubeletRunDirectory string) error {
 	klog.Warning("Cannot unmount filesystems on current OS, all mounted file systems will need to be manually unmounted")
 	return nil
 }

cmd/kubeadm/app/cmd/phases/reset/unmount_linux.go

@@ -24,30 +24,37 @@ import (
 	"strings"
 	"syscall"
 
+	"github.com/pkg/errors"
+
 	"k8s.io/klog/v2"
+
+	utilerrors "k8s.io/apimachinery/pkg/util/errors"
 )
 
 // unmountKubeletDirectory unmounts all paths that contain KubeletRunDirectory
-func unmountKubeletDirectory(absoluteKubeletRunDirectory string) error {
+func unmountKubeletDirectory(kubeletRunDirectory string) error {
 	raw, err := os.ReadFile("/proc/mounts")
 	if err != nil {
 		return err
 	}
 
-	if !strings.HasSuffix(absoluteKubeletRunDirectory, "/") {
+	if !strings.HasSuffix(kubeletRunDirectory, "/") {
 		// trailing "/" is needed to ensure that possibly mounted /var/lib/kubelet is skipped
-		absoluteKubeletRunDirectory += "/"
+		kubeletRunDirectory += "/"
 	}
 
+	var errList []error
 	mounts := strings.Split(string(raw), "\n")
 	for _, mount := range mounts {
 		m := strings.Split(mount, " ")
-		if len(m) < 2 || !strings.HasPrefix(m[1], absoluteKubeletRunDirectory) {
+		if len(m) < 2 || !strings.HasPrefix(m[1], kubeletRunDirectory) {
 			continue
 		}
+		klog.V(5).Infof("[reset] Unmounting %q", m[1])
 		if err := syscall.Unmount(m[1], 0); err != nil {
-			klog.Warningf("[reset] Failed to unmount mounted directory in %s: %s", absoluteKubeletRunDirectory, m[1])
+			errList = append(errList, errors.WithMessagef(err, "failed to unmount %q", m[1]))
 		}
 	}
-	return nil
+	return errors.Wrapf(utilerrors.NewAggregate(errList),
+		"encountered the following errors while unmounting directories in %q", kubeletRunDirectory)
 }