fix: store account id if already accessed (#908)

src/braket/aws/aws_session.py

@@ -85,7 +85,6 @@ def __init__(
             self.braket_client = self.boto_session.client(
                 "braket", config=self._config, endpoint_url=os.environ.get("BRAKET_ENDPOINT")
             )
-
         self._update_user_agent()
         self._custom_default_bucket = bool(default_bucket)
         self._default_bucket = default_bucket or os.environ.get("AMZN_BRAKET_OUT_S3_BUCKET")
@@ -101,14 +100,22 @@ def __init__(
         self._sts = None
         self._logs = None
         self._ecr = None
+        self._account_id = None
 
     @property
     def region(self) -> str:
         return self.boto_session.region_name
 
     @property
     def account_id(self) -> str:
-        return self.sts_client.get_caller_identity()["Account"]
+        """Gets the caller's account number.
+
+        Returns:
+            str: The account number of the caller.
+        """
+        if not self._account_id:
+            self._account_id = self.sts_client.get_caller_identity()["Account"]
+        return self._account_id
 
     @property
     def iam_client(self) -> client:

test/unit_tests/braket/aws/test_aws_session.py

@@ -58,7 +58,6 @@ def aws_session(boto_session, braket_client, account_id):
     _aws_session._sts.get_caller_identity.return_value = {
         "Account": account_id,
     }
-
     _aws_session._s3 = Mock()
     return _aws_session
 
@@ -998,6 +997,12 @@ def test_upload_to_s3(aws_session):
     aws_session._s3.upload_file.assert_called_with(filename, bucket, key)
 
 
+def test_account_id_idempotency(aws_session, account_id):
+    acc_id = aws_session.account_id
+    assert acc_id == aws_session.account_id
+    assert acc_id == account_id
+
+
 def test_upload_local_data(aws_session):
     with tempfile.TemporaryDirectory() as temp_dir:
         os.chdir(temp_dir)