add generator 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()
+}

pkg/target/generatorplugin_test.go

@@ -0,0 +1,73 @@
+/*
+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 target_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"sigs.k8s.io/kustomize/pkg/pgmconfig"
+	"sigs.k8s.io/kustomize/pkg/types"
+)
+
+func writeGenerator(th *KustTestHarness, path string) {
+	th.writeF(path, `
+apiVersion: strings.microwoosh.com/v1
+kind: ServiceGenerator
+metadata:
+  name: myServiceGenerator
+service: my-service
+port: "12345"
+`)
+}
+
+func TestGeneratorPlugin(t *testing.T) {
+	dir, err := filepath.Abs("../../..")
+	if err != nil {
+		t.Errorf("unexpected error %v", err)
+	}
+	os.Setenv(pgmconfig.XDG_CONFIG_HOME, dir)
+	defer os.Unsetenv(pgmconfig.XDG_CONFIG_HOME)
+
+	err = buildGoPlugins(dir, "ServiceGenerator")
+	if err != nil {
+		t.Errorf("unexpected error %v", err)
+	}
+
+	th := NewKustTestHarnessWithPluginConfig(
+		t, "/app", types.PluginConfig{GoEnabled: true})
+	th.writeK("/app", `
+generators:
+- serviceGenerator.yaml
+`)
+	writeGenerator(th, "/app/serviceGenerator.yaml")
+	m, err := th.makeKustTarget().MakeCustomizedResMap()
+	if err != nil {
+		t.Fatalf("Err: %v", err)
+	}
+	th.assertActualEqualsExpected(m, `
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: dev
+  name: my-service
+spec:
+  ports:
+  - port: 12345
+  selector:
+    app: dev
+`)
+}

pkg/target/kusttarget.go

@@ -155,7 +155,7 @@ func (kt *KustTarget) shouldAddHashSuffixesToGeneratedResources() bool {
 // holding customized resources and the data/rules used
 // to do so.  The name back references and vars are
 // not yet fixed.
-func (kt *KustTarget) AccumulateTarget() (
+func (kt *KustTarget) AccumulateTarget() ( // nolint: gocyclo
 	ra *accumulator.ResAccumulator, err error) {
 	// TODO(monopole): Get rid of the KustomizationErrors accumulator.
 	// It's not consistently used, and complicates tests.
@@ -173,6 +173,17 @@ func (kt *KustTarget) AccumulateTarget() (
 	if err != nil {
 		errs.Append(errors.Wrap(err, "MergeResourcesWithErrorOnIdCollision"))
 	}
+	resourceFromGenerators, err := kt.loadGeneratorPlugins()
+	if err != nil {
+		errs.Append(errors.Wrap(err, "failed to load resources from generators"))
+	}
+	if len(errs.Get()) > 0 {
+		return ra, errs
+	}
+	err = ra.MergeResourcesWithErrorOnIdCollision(resourceFromGenerators)
+	if err != nil {
+		errs.Append(errors.Wrap(err, "MergeResourcesWithErrorOnIdCollision"))
+	}
 	tConfig, err := config.MakeTransformerConfig(
 		kt.ldr, kt.kustomization.Configurations)
 	if err != nil {
@@ -340,3 +351,13 @@ func (kt *KustTarget) loadTransformerPlugins() ([]transformers.Transformer, erro
 	tl := plugins.NewTransformerLoader(kt.goPluginEnabled)
 	return tl.Load(transformerPluginConfigs)
 }
+
+func (kt *KustTarget) loadGeneratorPlugins() (resmap.ResMap, error) {
+	generatorPluginConfigs, err := kt.rFactory.FromFiles(
+		kt.ldr, kt.kustomization.Generators)
+	if err != nil {
+		return nil, err
+	}
+	gl := plugins.NewGeneratorLoader(kt.goPluginEnabled, kt.rFactory)
+	return gl.Load(generatorPluginConfigs)
+}

plugins/ServiceGenerator.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"bytes"
+	"text/template"
+
+	"sigs.k8s.io/kustomize/k8sdeps/kunstruct"
+	"sigs.k8s.io/kustomize/pkg/ifc"
+	"sigs.k8s.io/kustomize/pkg/resmap"
+	"sigs.k8s.io/kustomize/pkg/resource"
+)
+
+type plugin struct {
+	ServiceName string
+	Port        string
+}
+
+var Generator plugin
+
+var manifest = `
+apiVersion: v1
+kind: Service
+metadata:
+  labels:
+    app: dev
+  name: {{.ServiceName}}
+spec:
+  ports:
+  - port: {{.Port}}
+  selector:
+    app: dev
+`
+
+func (p *plugin) Config(k ifc.Kunstructured) error {
+	var err error
+	p.ServiceName, err = k.GetFieldValue("service")
+	if err != nil {
+		return err
+	}
+	p.Port, err = k.GetFieldValue("port")
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (p *plugin) Generate() (resmap.ResMap, error) {
+	var buf bytes.Buffer
+
+	temp := template.Must(template.New("manifest").Parse(manifest))
+	err := temp.Execute(&buf, p)
+	if err != nil {
+		return nil, err
+	}
+	rf := resmap.NewFactory(resource.NewFactory(kunstruct.NewKunstructuredFactoryImpl()))
+	return rf.NewResMapFromBytes(buf.Bytes())
+}