Add retries to image push.

This uses the default provided retry transport by
go-containerregistry as this originally had no retries
built in.

This is useful to avoid intermittent failures of image
registries when returning a retryable status code.

pkg/executor/push.go

@@ -41,6 +41,7 @@ import (
 	"github.com/google/go-containerregistry/pkg/v1/layout"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/google/go-containerregistry/pkg/v1/remote/transport"
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
@@ -311,7 +312,7 @@ func makeTransport(opts *config.KanikoOptions, registryName string, loader syste
 			}
 		}
 	}
-	return tr
+	return transport.NewRetry(tr)
 }
 
 // pushLayerToCache pushes layer (tagged with cacheKey) to opts.Cache

pkg/executor/push_test.go

@@ -283,6 +283,14 @@ func (m *mockedCertPool) append(path string) error {
 	return nil
 }
 
+type retryTransport struct {
+	inner http.RoundTripper
+}
+
+func (t *retryTransport) RoundTrip(in *http.Request) (out *http.Response, err error) {
+	return nil, nil
+}
+
 func Test_makeTransport(t *testing.T) {
 	registryName := "my.registry.name"
 
@@ -347,7 +355,7 @@ func Test_makeTransport(t *testing.T) {
 				return &certPool
 			}
 			transport := makeTransport(tt.opts, registryName, mockedSystemCertLoader)
-			tt.check(transport.(*http.Transport).TLSClientConfig, &certPool)
+			tt.check(transport.(*retryTransport).inner.(*http.Transport).TLSClientConfig, &certPool)
 		})
 	}
 }