fix(auto): resolve symlinked directory before walk (#8032)

plugin/auto/walk.go

@@ -14,12 +14,20 @@ import (
 func (a Auto) Walk() error {
 	// TODO(miek): should add something so that we don't stomp on each other.
 
+	// Resolve symlinks in the directory path so filepath.Walk will traverse it.
+	// filepath.Walk uses os.Lstat on the root and won't enter a symlinked directory.
+	// This is needed when DIR itself is a symlink (e.g., Kubernetes ConfigMap mounts).
+	dir := a.directory
+	if resolved, err := filepath.EvalSymlinks(a.directory); err == nil {
+		dir = resolved
+	}
+
 	toDelete := make(map[string]bool)
 	for _, n := range a.Names() {
 		toDelete[n] = true
 	}
 
-	filepath.Walk(a.directory, func(path string, info os.FileInfo, e error) error {
+	filepath.Walk(dir, func(path string, info os.FileInfo, e error) error {
 		if e != nil {
 			log.Warningf("error reading %v: %v", path, e)
 		}

plugin/auto/walk_test.go

@@ -45,6 +45,41 @@ func TestWalk(t *testing.T) {
 	}
 }
 
+func TestWalkSymlinkedDirectory(t *testing.T) {
+	t.Parallel()
+	tempdir, err := createFiles(t)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Create a symlink to the directory containing zone files,
+	// simulating a Kubernetes ConfigMap mount where the directory
+	// itself is a symlink.
+	symlinkDir := filepath.Join(t.TempDir(), "zones")
+	if err := os.Symlink(tempdir, symlinkDir); err != nil {
+		t.Fatal(err)
+	}
+
+	ldr := loader{
+		directory: symlinkDir,
+		re:        regexp.MustCompile(`db\.(.*)`),
+		template:  `${1}`,
+	}
+
+	a := Auto{
+		loader: ldr,
+		Zones:  &Zones{},
+	}
+
+	a.Walk()
+
+	for _, name := range []string{"example.com.", "example.org."} {
+		if _, ok := a.Z[name]; !ok {
+			t.Errorf("%s should have been added when directory is a symlink", name)
+		}
+	}
+}
+
 func TestWalkNonExistent(t *testing.T) {
 	t.Parallel()
 	nonExistingDir := "highly_unlikely_to_exist_dir"

plugin/auto/watcher_test.go

@@ -56,6 +56,13 @@ func TestSymlinks(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
+	// Resolve tempdir to handle platforms where temp paths contain symlinks
+	// (e.g., macOS where /var -> /private/var). Walk resolves the directory
+	// via EvalSymlinks, so stored paths use the resolved prefix.
+	tempdir, err = filepath.EvalSymlinks(tempdir)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	ldr := loader{
 		directory: tempdir,