add support for docker complaint registries for base image (#74)

cmd/kaniko-ecr/main.go

@@ -64,6 +64,11 @@ func main() {
 			Value:  "Dockerfile",
 			EnvVar: "PLUGIN_DOCKERFILE",
 		},
+		cli.StringFlag{
+			Name:   "docker-registry",
+			Usage:  "docker registry",
+			EnvVar: "PLUGIN_DOCKER_REGISTRY,DOCKER_REGISTRY",
+		},
 		cli.StringFlag{
 			Name:   "docker-username",
 			Usage:  "docker username",
@@ -242,6 +247,7 @@ func run(c *cli.Context) error {
 	noPush := c.Bool("no-push")
 
 	dockerConfig, err := createDockerConfig(
+		c.String("docker-registry"),
 		c.String("docker-username"),
 		c.String("docker-password"),
 		c.String("access-key"),
@@ -328,12 +334,16 @@ func run(c *cli.Context) error {
 	return plugin.Exec()
 }
 
-func createDockerConfig(dockerUsername, dockerPassword, accessKey, secretKey,
+func createDockerConfig(dockerRegistry, dockerUsername, dockerPassword, accessKey, secretKey,
 	registry, assumeRole, externalId, region string, noPush bool) (*docker.Config, error) {
 	dockerConfig := docker.NewConfig()
 
 	if dockerUsername != "" {
-		dockerConfig.SetAuth(docker.RegistryV1, dockerUsername, dockerPassword)
+		// if no docker registry provided, use dockerhub by default
+		if len(dockerRegistry) == 0 {
+			dockerRegistry = docker.RegistryV1
+		}
+		dockerConfig.SetAuth(dockerRegistry, dockerUsername, dockerPassword)
 	}
 
 	if assumeRole != "" {

cmd/kaniko-ecr/main_test.go

@@ -10,6 +10,7 @@ import (
 
 func TestCreateDockerConfig(t *testing.T) {
 	got, err := createDockerConfig(
+		"",
 		"docker-username",
 		"docker-password",
 		"access-key",
@@ -34,10 +35,37 @@ func TestCreateDockerConfig(t *testing.T) {
 	}
 }
 
+func TestCreateDockerConfigFromGivenRegistry(t *testing.T) {
+	got, err := createDockerConfig(
+		"docker-registry",
+		"docker-username",
+		"docker-password",
+		"access-key",
+		"secret-key",
+		"ecr-registry",
+		"",
+		"",
+		"",
+		false,
+	)
+	if err != nil {
+		t.Error("failed to create docker config")
+	}
+
+	want := docker.NewConfig()
+	want.SetAuth("docker-registry", "docker-username", "docker-password")
+	want.SetCredHelper(docker.RegistryECRPublic, "ecr-login")
+	want.SetCredHelper("ecr-registry", "ecr-login")
+	if !reflect.DeepEqual(want, got) {
+		t.Errorf("not equal:\n  want: %#v\n   got: %#v", want, got)
+	}
+}
+
 func TestCreateDockerConfigKanikoOneDotEight(t *testing.T) {
 	os.Setenv(kanikoVersionEnv, "1.8.1")
 	defer os.Setenv(kanikoVersionEnv, "")
 	got, err := createDockerConfig(
+		"",
 		"docker-username",
 		"docker-password",
 		"access-key",