config: recognize Ignition configs and no-op

config/validate/validate.go

@@ -40,6 +40,8 @@ func Validate(userdataBytes []byte) (Report, error) {
 		return Report{}, nil
 	case config.IsScript(string(userdataBytes)):
 		return Report{}, nil
+	case config.IsIgnitionConfig(string(userdataBytes)):
+		return Report{}, nil
 	case config.IsCloudConfig(string(userdataBytes)):
 		return validateCloudConfig(userdataBytes, Rules)
 	default:

config/validate/validate_test.go

@@ -111,6 +111,16 @@ func TestValidate(t *testing.T) {
 		{
 			config: "#!/bin/bash\necho hey",
 		},
+		{
+			config: "{}",
+			report: Report{entries: []Entry{{entryError, `must be "#cloud-config" or begin with "#!"`, 1}}},
+		},
+		{
+			config: `{"ignitionVersion":0}`,
+		},
+		{
+			config: `{"ignitionVersion":1}`,
+		},
 	}
 
 	for i, tt := range tests {