Store Region-info in UserAgent-header

moto/core/models.py

@@ -10,6 +10,7 @@ import six
 import types
 from io import BytesIO
 from collections import defaultdict
+from botocore.config import Config
 from botocore.handlers import BUILTIN_HANDLERS
 from botocore.awsrequest import AWSResponse
 from six.moves.urllib.parse import urlparse
@@ -416,6 +417,8 @@ class ServerModeMockAWS(BaseMockAWS):
         import mock
 
         def fake_boto3_client(*args, **kwargs):
+            service, region = args
+            kwargs["config"] = Config(user_agent_extra="region/"+region)
             if "endpoint_url" not in kwargs:
                 kwargs["endpoint_url"] = "http://localhost:5000"
             return real_boto3_client(*args, **kwargs)

moto/core/responses.py

@@ -188,6 +188,7 @@ class BaseResponse(_TemplateEnvironmentMixin, ActionAuthenticatorMixin):
     default_region = "us-east-1"
     # to extract region, use [^.]
     region_regex = re.compile(r"\.(?P<region>[a-z]{2}-[a-z]+-\d{1})\.amazonaws\.com")
+    region_from_useragent_regex = re.compile(r"region/(?P<region>[a-z]{2}-[a-z]+-\d{1})")
     param_list_regex = re.compile(r"(.*)\.(\d+)\.")
     access_key_regex = re.compile(
         r"AWS.*(?P<access_key>(?<![A-Z0-9])[A-Z0-9]{20}(?![A-Z0-9]))[:/]"
@@ -272,9 +273,12 @@ class BaseResponse(_TemplateEnvironmentMixin, ActionAuthenticatorMixin):
         self.response_headers = {"server": "amazon.com"}
 
     def get_region_from_url(self, request, full_url):
-        match = self.region_regex.search(full_url)
-        if match:
-            region = match.group(1)
+        url_match = self.region_regex.search(full_url)
+        user_agent_match = self.region_from_useragent_regex.search(request.headers["User-Agent"])
+        if url_match:
+            region = url_match.group(1)
+        elif user_agent_match:
+            region = user_agent_match.group(1)
         elif (
             "Authorization" in request.headers
             and "AWS4" in request.headers["Authorization"]