WIP RoundTripWithRetryBackoff transport

v3/round_trip_with_retry_backoff.go

@@ -0,0 +1,41 @@
+package heroku
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/cenkalti/backoff"
+)
+
+func RoundTripWithRetryBackoff(req *http.Request) (*http.Response, error) {
+	var lastResponse *http.Response
+	var lastError error
+
+	retryableRoundTrip := func() error {
+		lastResponse, lastError = http.DefaultTransport.RoundTrip(req)
+		// Detect Heroku API rate limiting
+		// https://devcenter.heroku.com/articles/platform-api-reference#client-error-responses
+		if lastResponse.StatusCode == 429 {
+			return fmt.Errorf("Heroku API rate limited: 429 Too Many Requests")
+		}
+		return nil
+	}
+
+	err := backoff.Retry(retryableRoundTrip, backoff.NewExponentialBackOff())
+	// Propagate the rate limit error when retries eventually fail.
+	if err != nil {
+		if lastResponse != nil {
+			lastResponse.Body.Close()
+		}
+		return nil, err
+	}
+	// Propagate all other response errors.
+	if lastError != nil {
+		if lastResponse != nil {
+			lastResponse.Body.Close()
+		}
+		return nil, lastError
+	}
+
+	return lastResponse, nil
+}