fix: add https to regional STS endpoint (#1035)

Author: laurenyu

src/sagemaker/utils.py

@@ -553,7 +553,7 @@ def sts_regional_endpoint(region):
     Returns:
         str: AWS STS regional endpoint
     """
-    return "sts.{}.amazonaws.com".format(region)
+    return "https://sts.{}.amazonaws.com".format(region)
 
 
 class DeferredError(object):

tests/unit/test_utils.py

@@ -22,6 +22,7 @@
 import time
 
 from boto3 import exceptions
+import botocore
 import pytest
 from mock import call, patch, Mock, MagicMock
 
@@ -564,4 +565,5 @@ def walk():
 
 def test_sts_regional_endpoint():
     endpoint = sagemaker.utils.sts_regional_endpoint("us-west-2")
-    assert endpoint == "sts.us-west-2.amazonaws.com"
+    assert endpoint == "https://sts.us-west-2.amazonaws.com"
+    assert botocore.utils.is_valid_endpoint_url(endpoint)