Add url to validation (#2874)

* Add url to validation

* Fix pylint issue

* Clean-up

homeassistant/helpers/config_validation.py

@@ -1,5 +1,6 @@
 """Helpers for config validation using voluptuous."""
 from datetime import timedelta
+from urllib.parse import urlparse
 
 from typing import Any, Union, TypeVar, Callable, Sequence, List, Dict
 
@@ -255,6 +256,17 @@ def time_zone(value):
 weekdays = vol.All(ensure_list, [vol.In(WEEKDAYS)])
 
 
+# pylint: disable=no-value-for-parameter
+def url(value: Any) -> str:
+    """Validate an URL."""
+    url_in = str(value)
+
+    if urlparse(url_in).scheme in ['http', 'https']:
+        return vol.Schema(vol.Url())(url_in)
+
+    raise vol.Invalid('invalid url')
+
+
 # Validator helpers
 
 def key_dependency(key, dependency):