Backoff indicators

Backoff header on heavy load

A Backoff header will be added to the success responses (>=200 and <400) when the server is under heavy load. It provides the client with a number of seconds during which it should avoid doing unnecessary requests.

Backoff: 30
note:The back-off time is configurable on the server.
note:In other implementations at Mozilla, there was X-Weave-Backoff and X-Backoff but the X- prefix for header has been deprecated since.

Retry-After indicators

A Retry-After header will be added to error responses (>=500), telling the client how many seconds it should wait before trying again.

Retry-After: 30