move load restrictions

api/types/erronlybuiltinpluginsallowed.go

@@ -0,0 +1,32 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package types
+
+import (
+	"fmt"
+	"github.com/pkg/errors"
+)
+
+type errOnlyBuiltinPluginsAllowed struct {
+	name string
+}
+
+func (e *errOnlyBuiltinPluginsAllowed) Error() string {
+	return fmt.Sprintf(
+		"external plugins disabled; unable to load external plugin '%s'",
+		e.name)
+}
+
+func NewErrOnlyBuiltinPluginsAllowed(n string) *errOnlyBuiltinPluginsAllowed {
+	return &errOnlyBuiltinPluginsAllowed{name: n}
+}
+
+func IsErrOnlyBuiltinPluginsAllowed(err error) bool {
+	_, ok := err.(*errOnlyBuiltinPluginsAllowed)
+	if ok {
+		return true
+	}
+	_, ok = errors.Cause(err).(*errOnlyBuiltinPluginsAllowed)
+	return ok
+}