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

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"