Add hash function which only considers mtime when snapshotting

pkg/util/util.go

@@ -61,3 +61,17 @@ func Hasher() func(string) (string, error) {
 	}
 	return hasher
 }
+
+// Hasher returns a hash function, which only looks at mtime to determine if a file has changed
+func MtimeHasher() func(string) (string, error) {
+	hasher := func(p string) (string, error) {
+		h := md5.New()
+		fi, err := os.Lstat(p)
+		if err != nil {
+			return "", err
+		}
+		h.Write([]byte(fi.ModTime().String()))
+		return hex.EncodeToString(h.Sum(nil)), nil
+	}
+	return hasher
+}