Retry HTTP requests on bad gateways and code 429

Code 429 is used by the server-side throttling code.

clientutil/retry.go

@@ -33,12 +33,20 @@ func Retry(op backoff.Operation, b backoff.BackOff) error {
 	return backoff.Retry(innerOp, b)
 }
 
-var errHTTPBackOff = errors.New("http status 503")
+var errHTTPBackOff = errors.New("temporary http error")
+
+func isStatusTemporary(code int) bool {
+	switch code {
+	case http.StatusTooManyRequests, http.StatusBadGateway, http.StatusServiceUnavailable, http.StatusGatewayTimeout:
+		return true
+	default:
+		return false
+	}
+}
 
 // RetryHTTPDo retries an HTTP request until it succeeds, according to
 // the backoff policy b. It will retry on temporary network errors and
-// upon receiving specific throttling HTTP errors (currently just
-// status code 503).
+// upon receiving specific temporary HTTP errors.
 func RetryHTTPDo(client *http.Client, req *http.Request, b backoff.BackOff) (*http.Response, error) {
 	var resp *http.Response
 	op := func() error {
@@ -49,7 +57,7 @@ func RetryHTTPDo(client *http.Client, req *http.Request, b backoff.BackOff) (*ht
 
 		var err error
 		resp, err = client.Do(req)
-		if err == nil && resp.StatusCode == 503 {
+		if err == nil && isStatusTemporary(resp.StatusCode) {
 			resp.Body.Close()
 			return errHTTPBackOff
 		}