Add ability to set Retry-After header to 429 Too Many Requests response.

Added optional retry_after_secs to TooManyRequests exception init.
This brings the output in line with the HTTP spec.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/werkzeug/exceptions.py b/src/werkzeug/exceptions.py
index edc6454a..7b64048f 100644
--- a/src/werkzeug/exceptions.py
+++ b/src/werkzeug/exceptions.py
@@ -600,11 +600,29 @@ class TooManyRequests(HTTPException):
     to identify users and their request rates). The server may include a
     "Retry-After" header to indicate how long the user should wait before
     retrying.
+
+    .. versionchanged:: 0.16.1
+        ``retry_after_secs`` was added as the first argument, ahead of
+        ``description``.
     """
 
     code = 429
     description = "This user has exceeded an allotted request count. Try again later."
 
+    def __init__(self, description=None, retry_after_secs=None):
+        """
+        Use the optional value of retry_after_secs to specify the number of seconds
+        to wait for a retry attempt.
+        """
+        HTTPException.__init__(self, description)
+        self.retry_after_secs = retry_after_secs
+
+    def get_headers(self, environ=None):
+        headers = HTTPException.get_headers(self, environ)
+        if self.retry_after_secs:
+            headers.append(("Retry-After", str(self.retry_after_secs)))
+        return headers
+
 
 class RequestHeaderFieldsTooLarge(HTTPException):
     """*431* `Request Header Fields Too Large`