Add support for tuples in get_attr

botocore/endpoint_provider.py

@@ -42,7 +42,7 @@
 logger = logging.getLogger(__name__)
 
 TEMPLATE_STRING_RE = re.compile(r"\{[a-zA-Z#]+\}")
-GET_ATTR_RE = re.compile(r"(\w+)\[(\d+)\]")
+GET_ATTR_RE = re.compile(r"(\w*)\[(\d+)\]")
 VALID_HOST_LABEL_RE = re.compile(
     r"^(?!-)[a-zA-Z\d-]{1,63}(?<!-)$",
 )
@@ -169,17 +169,20 @@ def get_attr(self, value, path):
         names indicates the one to the right is nested. The index will always occur at
         the end of the path.
 
-        :type value: dict or list
+        :type value: dict or tuple
         :type path: str
         :rtype: Any
         """
         for part in path.split("."):
+            if value is None:
+                return None
             match = GET_ATTR_RE.search(part)
             if match is not None:
                 name, index = match.groups()
                 index = int(index)
-                value = value.get(name)
-                if value is None or index >= len(value):
+                if name:
+                    value = value.get(name)
+                if index >= len(value):
                     return None
                 return value[index]
             else:

tests/unit/test_endpoint_provider.py

@@ -510,3 +510,13 @@ def test_aws_is_virtual_hostable_s3_bucket_allow_subdomains(
         rule_lib.aws_is_virtual_hostable_s3_bucket(bucket, True)
         == expected_value
     )
+
+
+def test_get_attr_can_get_dictionary_index(rule_lib):
+    result = rule_lib.get_attr({"foo": ['bar']}, 'foo[0]')
+    assert result == "bar"
+
+
+def test_get_attr_can_get_list_index(rule_lib):
+    result = rule_lib.get_attr(("foo",), '[0]')
+    assert result == "foo"