Panel_Iframe - Allow relative urls in config (#11832)

* Panel_Iframe - Allow relative urls in config

* change regex to check for starting forward slash only

* Change error message and const name

homeassistant/components/panel_iframe.py

@@ -8,22 +8,28 @@ import asyncio
 
 import voluptuous as vol
 
+from homeassistant.const import (CONF_ICON, CONF_URL)
 import homeassistant.helpers.config_validation as cv
 
-DOMAIN = 'panel_iframe'
 DEPENDENCIES = ['frontend']
 
+DOMAIN = 'panel_iframe'
+
 CONF_TITLE = 'title'
-CONF_ICON = 'icon'
-CONF_URL = 'url'
+
+CONF_RELATIVE_URL_ERROR_MSG = "Invalid relative URL. Absolute path required."
+CONF_RELATIVE_URL_REGEX = r'\A/'
 
 CONFIG_SCHEMA = vol.Schema({
     DOMAIN: vol.Schema({
         cv.slug: {
             vol.Optional(CONF_TITLE): cv.string,
             vol.Optional(CONF_ICON): cv.icon,
-            # pylint: disable=no-value-for-parameter
-            vol.Required(CONF_URL): vol.Url(),
+            vol.Required(CONF_URL): vol.Any(
+                vol.Match(
+                    CONF_RELATIVE_URL_REGEX,
+                    msg=CONF_RELATIVE_URL_ERROR_MSG),
+                cv.url),
         }})}, extra=vol.ALLOW_EXTRA)