Add RetryError

- Exposes additional information such as request and status code
  to help determine (via a Predicate) whether the RoundTripper should retry or not

Authored-by: Dennis Leon <leonde@vmware.com>

pkg/v1/remote/transport/retry.go

@@ -15,6 +15,7 @@
 package transport
 
 import (
+	"context"
 	"net/http"
 	"time"
 
@@ -49,7 +50,7 @@ type options struct {
 // Backoff is an alias of retry.Backoff to expose this configuration option to consumers of this lib
 type Backoff = retry.Backoff
 
-// This is implemented by several errors in the net package as well as our
+// Temporary is implemented by several errors in the net package as well as our
 // transport.Error
 type Temporary interface {
 	Temporary() bool
@@ -87,10 +88,54 @@ func NewRetry(inner http.RoundTripper, opts ...Option) http.RoundTripper {
 	}
 }
 
+// RetryError is an error returned by retryTransport. Exposes additional information such as request and status code
+// to help determine (via a Predicate) whether the RoundTripper should retry or not.
+type RetryError struct {
+	Inner error
+	// The http status code returned.
+	StatusCode int
+	// The request that failed.
+	Request *http.Request
+}
+
+// Temporary delegates to the wrapped error if it exists
+func (e *RetryError) Temporary() bool {
+	if te, ok := e.Inner.(Temporary); ok && te.Temporary() {
+		return true
+	}
+
+	return false
+}
+
+// Check that RetryError implements error
+var _ error = (*RetryError)(nil)
+
+func (e *RetryError) Error() string {
+	if e.Inner != nil {
+		return e.Inner.Error()
+	}
+
+	return ""
+}
+
 func (t *retryTransport) RoundTrip(in *http.Request) (out *http.Response, err error) {
 	roundtrip := func() error {
 		out, err = t.inner.RoundTrip(in)
-		return err
+
+		if err == context.DeadlineExceeded {
+			return err
+		}
+
+		var statusCode int
+		if out != nil {
+			statusCode = out.StatusCode
+		}
+
+		return &RetryError{
+			Inner:      err,
+			StatusCode: statusCode,
+			Request:    in,
+		}
 	}
 	retry.Retry(roundtrip, t.predicate, t.backoff)
 	return

pkg/v1/remote/transport/transport.go

@@ -107,6 +107,7 @@ type Transport struct {
 	inner http.RoundTripper
 }
 
+// RoundTrip delegates to the inner RoundTripper
 func (t *Transport) RoundTrip(in *http.Request) (*http.Response, error) {
 	return t.inner.RoundTrip(in)
 }