Don't fall back to http on 5xx response (#344)

* Don't fall back to http on 5xx response

When retching the registry limit we will get 503 or if the registry is having some problems we will get 5xx in response. In this case we don't want to fallback to http because it can make the build fail and retry the same request instead.

* move httpFallbackDisabled into a variable

lib/utils/httputil/httputil.go

@@ -304,10 +304,15 @@ func Send(method, rawurl string, options ...SendOption) (resp *http.Response, er
 				opts.retry.backoffMax)
 		}
 		resp, err = client.Do(req)
+
+		httpFallbackDisabled := opts.httpFallbackDisabled
+		if !httpFallbackDisabled && is5xxResponse(resp) {
+			httpFallbackDisabled = true
+		}
 		// Retry without tls. During migration there would be a time when the
 		// component receiving the tls request does not serve https response.
 		// TODO (@evelynl): disable retry after tls migration.
-		if err != nil && req.URL.Scheme == "https" && !opts.httpFallbackDisabled {
+		if err != nil && req.URL.Scheme == "https" && !httpFallbackDisabled {
 			log.Warnf("Failed to send https request: %s. Retrying with http...", err)
 			var httpReq *http.Request
 			httpReq, err = newRequest(method, opts)
@@ -385,3 +390,7 @@ func min(a, b time.Duration) time.Duration {
 	}
 	return b
 }
+
+func is5xxResponse(resp *http.Response) bool {
+	return resp != nil && resp.StatusCode >= 500
+}