agent/utils/sign_http_request.go
func SignHTTPRequest(req *http.Request, region, service string, creds *credentials.Credentials, body io.ReadSeeker) error {
	signer := v4.NewSigner(creds)
	_, err := signer.Sign(req, body, service, region, time.Now())
	if err != nil {
		seelog.Warnf("Signing HTTP request failed: %v", err)
		return errors.Wrap(err, "aws sdk http signer: failed to sign http request")
	}
	return nil
}
func SignHTTPRequest(req *http.Request, region, service string, creds *credentials.Credentials, body io.ReadSeeker) error {
	signer := v4.NewSigner(creds)
	_, err := signer.Sign(req, body, service, region, time.Now())
	if err != nil {
		seelog.Warnf("Signing HTTP request failed: %v", err)
		return errors.Wrap(err, "aws sdk http signer: failed to sign http request")
	}
	return nil
}
// SignHTTPRequest signs an http.Request struct with authv4 using the given region, service, and credentials.