POST / HTTP/1.1
Content-Length:11
Host:foo-service.foo-region.amazonaws.com
X-Amz-Date:20150830T123600Z
Authorization: AWS4-HMAC-SHA256 Credential=foo-akid/20150830/foo-region/foo-service/aws4_request, SignedHeaders=content-length;host;x-amz-date, Signature=9025f1937fb114f77158a8bf0170e1ec1a9aa29806bc7800ca850966cd32920b

foo-payload