Honor Retry-After headers on libcloud exceptions
It seems to be a bug on libcloud that could make nodemanager behave erratically on certain error situations with cloud providers.
As for libcloud 2.2.1, it seems that neither
RateLimitReachedError get assigned the Retry-After header value, as it was removed from the
exception_from_message() call on
Retry-After header should accept a date in the future as detailed on https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html (relevant part copied below):
The Retry-After response-header field can be used with a 503 (Service Unavailable) response to indicate how long the service is expected to be unavailable to the requesting client. This field MAY also be used with any 3xx (Redirection) response to indicate the minimum time the user-agent is asked wait before issuing the redirected request. The value of this field can be either an HTTP-date or an integer number of seconds (in decimal) after the time of the response.
Retry-After = "Retry-After" ":" ( HTTP-date | delta-seconds )
Two examples of its use are
Retry-After: Fri, 31 Dec 1999 23:59:59 GMT Retry-After: 120