readme: add --registry-mirror

Signed-off-by: Yoan Blanc <yoan@dosimple.ch>

README.md

@@ -46,6 +46,7 @@ _If you are interested in contributing to kaniko, see [DEVELOPMENT.md](DEVELOPME
     - [--insecure-pull](#--insecure-pull)
     - [--no-push](#--no-push)
     - [--oci-layout-path](#--oci-layout-path)
+    - [--registry-mirror](#--registry-mirror)
     - [--reproducible](#--reproducible)
     - [--single-snapshot](#--single-snapshot)
     - [--snapshotMode](#--snapshotmode)
@@ -441,6 +442,10 @@ Set this flag if you want to pull images from a plain HTTP registry. It is suppo
 
 Set this flag if you only want to build the image, without pushing to a registry.
 
+#### --registry-mirror
+
+Set this flag if you want to use a registry mirror instead of default `index.docker.io`.
+
 #### --reproducible
 
 Set this flag to strip timestamps out of the built image and make it reproducible.

integration/integration_test.go

@@ -171,7 +171,7 @@ func TestMain(m *testing.M) {
 		},
 		{
 			name:    "Building kaniko image using registry-mirror",
-			command: []string{"docker", "build", "--registry-mirror", "https://mirror.gcr.io", "-t", ExecutorImage, "-f", "../deploy/Dockerfile", ".."},
+			command: []string{"docker", "build", "--registry-mirror", "mirror.gcr.io", "-t", ExecutorImage, "-f", "../deploy/Dockerfile", ".."},
 		},
 	}
 

pkg/util/image_util_test.go

@@ -102,7 +102,7 @@ func Test_ScratchImageFromMirror(t *testing.T) {
 	actual, err := RetrieveSourceImage(config.KanikoStage{
 		Stage: stages[1],
 	}, &config.KanikoOptions{
-		RegistryMirror: "https://mirror.gcr.io",
+		RegistryMirror: "mirror.gcr.io",
 	})
 	expected := empty.Image
 	testutil.CheckErrorAndDeepEqual(t, false, err, expected, actual)