Merge pull request #951 from Liujingfang1/generatorplugins

add support for generator go-plugins

pkg/plugins/generators.go

@@ -0,0 +1,98 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package plugins
+
+import (
+	"fmt"
+	"path/filepath"
+	"plugin"
+
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/pkg/pgmconfig"
+	"sigs.k8s.io/kustomize/pkg/resid"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/resource"
+)
+
+const generatorSymbol = "Generator"
+
+type Generatable interface {
+	Generate() (resmap.ResMap, error)
+}
+
+type generatorLoader struct {
+	pluginDir string
+	enabled   bool
+	rf        *resmap.Factory
+}
+
+func NewGeneratorLoader(b bool, f *resmap.Factory) generatorLoader {
+	return generatorLoader{
+		pluginDir: filepath.Join(pgmconfig.ConfigRoot(), pgmconfig.PluginsDir),
+		enabled:   b,
+		rf:        f,
+	}
+}
+
+func (l generatorLoader) Load(rm resmap.ResMap) (resmap.ResMap, error) {
+	if len(rm) == 0 {
+		return nil, nil
+	}
+	if !l.enabled {
+		return nil, fmt.Errorf("plugin is not enabled")
+	}
+	var result resmap.ResMap
+	for id, res := range rm {
+		r, err := l.load(id, res)
+		if err != nil {
+			return nil, err
+		}
+		result, err = resmap.MergeWithErrorOnIdCollision(result, r)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return result, nil
+}
+
+func (l generatorLoader) load(id resid.ResId, res *resource.Resource) (resmap.ResMap, error) {
+	fileName := filepath.Join(l.pluginDir, id.Gvk().Kind+".so")
+	goPlugin, err := plugin.Open(fileName)
+	if err != nil {
+		return nil, fmt.Errorf("plugin %s file not opened", fileName)
+	}
+
+	symbol, err := goPlugin.Lookup(generatorSymbol)
+	if err != nil {
+		return nil, fmt.Errorf("plugin %s fails lookup", fileName)
+	}
+
+	c, ok := symbol.(Configurable)
+	if !ok {
+		return nil, fmt.Errorf("plugin %s not configurable", fileName)
+	}
+	err = c.Config(res)
+	if err != nil {
+		return nil, errors.Wrapf(err, "plugin %s fails configuration", fileName)
+	}
+
+	g, ok := c.(Generatable)
+	if !ok {
+		return nil, fmt.Errorf("plugin %s not a transformer", fileName)
+	}
+	return g.Generate()
+}