Add region keyword argument to login.

This allows users to specify what AWS region they want to work with.

src/tiledb/cloud/__init__.py

@@ -17,6 +17,7 @@
 from .array import register_array
 from .array import share_array
 from .array import unshare_array
+from .client import AwsRegion
 from .client import Config
 from .client import Ctx
 from .client import list_arrays
@@ -89,4 +90,5 @@
     "last_udf_task",
     "task",
     "TileDBCloudError",
+    "AwsRegion",
 )

src/tiledb/cloud/client.py

@@ -63,6 +63,24 @@ def Ctx(config=None):
     return tiledb.Ctx(Config(config))
 
 
+class AwsRegion(enum.Enum):
+    """
+    The AWS cloud regions that are currently supported.
+
+    US_EAST_1 = North America, United States (Virginia)
+    US_WEST_1 = North America, United States (California)
+    EU_WEST_1 = Europe, Ireland
+    EU_WEST_2 = Europe, London
+    AP_SOUTHEAST_1 = Asia, Singapore
+    """
+
+    US_EAST_1 = "us-east-1.aws."
+    US_WEST_1 = "us-west-1.aws."
+    EU_WEST_1 = "eu-west-1.aws."
+    EU_WEST_2 = "eu-west-2.aws."
+    AP_SOUTHEAST_1 = "ap-southeast-1.aws."
+
+
 def login(
     token=None,
     username=None,
@@ -71,6 +89,7 @@ def login(
     verify_ssl=None,
     no_session=False,
     threads=None,
+    region=None,
 ):
     """
     Login to cloud service
@@ -83,10 +102,21 @@ def login(
     :param no_session: don't create a session token on login,
         store instead username/password
     :param threads: number of threads to enable for concurrent requests
+    :param region: the AWS region to run code in
     :return:
     """
     if host is None:
         host = config.default_host
+    if region is not None:
+        if region not in AwsRegion:
+            raise Exception("Invalid cloud region provided")
+        # Overwrite the host using the given region.
+        orig_url = urllib3.util.parse_url(host)
+        region_url = urllib3.util.Url(
+            scheme=orig_url.scheme,
+            host=region.value + orig_url.host,
+        )
+        host = region_url.url
 
     if (token is None or token == "") and (
         (username is None or username == "") and (password is None or password == "")