Move data dir into position before creating CNI symlinks

Addresses issue where CNI bin symlinks were created with targets that were not yet valid, which caused external container runtimes that rely on filesystem notifications to detect changes to think that the bins did not exist.

Signed-off-by: Brad Davidson <[email protected]>
(cherry picked from commit b3ac144)
Signed-off-by: Brad Davidson <[email protected]>

Author: brandond

cmd/k3s/main.go

@@ -308,6 +308,25 @@ func extract(dataDir string) (string, error) {
 		return "", err
 	}
 
+	// Rotate 'current' symlink into 'previous', and create a new 'current' that points
+	// at the new directory.
+	currentSymLink := filepath.Join(dataDir, "data", "current")
+	previousSymLink := filepath.Join(dataDir, "data", "previous")
+	if _, err := os.Lstat(currentSymLink); err == nil {
+		if err := os.Rename(currentSymLink, previousSymLink); err != nil {
+			return "", err
+		}
+	}
+	if err := os.Symlink(dir, currentSymLink); err != nil {
+		return "", err
+	}
+
+	// Rename the new directory into place after updating symlinks, so that the k3s binary check at the start
+	// of this function only succeeds if everything else has been completed successfully.
+	if err := os.Rename(tempDest, dir); err != nil {
+		return "", err
+	}
+
 	// Create a stable CNI bin dir and place it first in the path so that users have a
 	// consistent location to drop their own CNI plugin binaries.
 	cniPath := filepath.Join(dataDir, "data", "cni")
@@ -326,13 +345,13 @@ func extract(dataDir string) (string, error) {
 	// Non-symlink plugins in the stable CNI bin dir will not be overwritten, to allow users to replace our
 	// CNI plugins with their own versions if they want. Note that the cni multicall binary itself is always
 	// symlinked into the stable bin dir and should not be replaced.
-	ents, err := os.ReadDir(filepath.Join(tempDest, "bin"))
+	ents, err := os.ReadDir(filepath.Join(dir, "bin"))
 	if err != nil {
 		return "", err
 	}
 	for _, ent := range ents {
 		if info, err := ent.Info(); err == nil && info.Mode()&fs.ModeSymlink != 0 {
-			if target, err := os.Readlink(filepath.Join(tempDest, "bin", ent.Name())); err == nil && target == "cni" {
+			if target, err := os.Readlink(filepath.Join(dir, "bin", ent.Name())); err == nil && target == "cni" {
 				src := filepath.Join(cniPath, ent.Name())
 				// Check if plugin already exists in stable CNI bin dir
 				if info, err := os.Lstat(src); err == nil {
@@ -353,25 +372,6 @@ func extract(dataDir string) (string, error) {
 		}
 	}
 
-	// Rotate 'current' symlink into 'previous', and create a new 'current' that points
-	// at the new directory.
-	currentSymLink := filepath.Join(dataDir, "data", "current")
-	previousSymLink := filepath.Join(dataDir, "data", "previous")
-	if _, err := os.Lstat(currentSymLink); err == nil {
-		if err := os.Rename(currentSymLink, previousSymLink); err != nil {
-			return "", err
-		}
-	}
-	if err := os.Symlink(dir, currentSymLink); err != nil {
-		return "", err
-	}
-
-	// Rename the new directory into place after updating symlinks, so that the k3s binary check at the start
-	// of this function only succeeds if everything else has been completed successfully.
-	if err := os.Rename(tempDest, dir); err != nil {
-		return "", err
-	}
-
 	return dir, nil
 }