read config file

pkg/config/transform.go

@@ -25,6 +25,8 @@ package config
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
+	"os"
 
 	"github.com/docker/go-connections/nat"
 	cliutil "github.com/rancher/k3d/v4/cmd/util" // TODO: move parseapiport to pkg
@@ -252,11 +254,24 @@ func TransformSimpleToClusterConfig(ctx context.Context, runtime runtimes.Runtim
 		log.Tracef("Parsed registry reference: %+v", reg)
 		clusterCreateOpts.Registries.Use = append(clusterCreateOpts.Registries.Use, reg)
 	}
-	var k3sRegistry *k3s.Registry
-	if err := yaml.Unmarshal([]byte(simpleConfig.Registries.Config), k3sRegistry); err != nil {
-		return nil, fmt.Errorf("Failed to read registry configuration: %+v", err)
+
+	if simpleConfig.Registries.Config != "" {
+		var k3sRegistry *k3s.Registry
+		registryConfigFile, err := os.Open(simpleConfig.Registries.Config)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to open registry config file at %s: %+v", simpleConfig.Registries.Config, err)
+		}
+		configBytes, err := ioutil.ReadAll(registryConfigFile)
+		if err != nil {
+			return nil, fmt.Errorf("Failed to read registry config file at %s: %+v", registryConfigFile.Name(), err)
+		}
+
+		if err := yaml.Unmarshal(configBytes, &k3sRegistry); err != nil {
+			return nil, fmt.Errorf("Failed to read registry configuration: %+v", err)
+		}
+		log.Tracef("Registry: read config from input:\n%+v", k3sRegistry)
+		clusterCreateOpts.Registries.Config = k3sRegistry
 	}
-	log.Tracef("Registry: read config from input:\n%+v", k3sRegistry)
 
 	/**********************
 	 * Kubeconfig Options *