Add support for versioned configuration in admission

pkg/admission/BUILD

@@ -13,6 +13,7 @@ go_library(
     srcs = [
         "attributes.go",
         "chain.go",
+        "config.go",
         "errors.go",
         "handler.go",
         "interfaces.go",
@@ -20,7 +21,12 @@ go_library(
     ],
     tags = ["automanaged"],
     deps = [
+        "//pkg/api:go_default_library",
         "//pkg/api/errors:go_default_library",
+        "//pkg/apis/componentconfig:go_default_library",
+        "//pkg/apis/componentconfig/v1alpha1:go_default_library",
+        "//pkg/util/sets:go_default_library",
+        "//vendor:github.com/ghodss/yaml",
         "//vendor:github.com/golang/glog",
         "//vendor:k8s.io/apimachinery/pkg/api/meta",
         "//vendor:k8s.io/apimachinery/pkg/runtime",
@@ -33,10 +39,17 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["chain_test.go"],
+    srcs = [
+        "chain_test.go",
+        "config_test.go",
+    ],
     library = ":go_default_library",
     tags = ["automanaged"],
-    deps = ["//vendor:k8s.io/apimachinery/pkg/runtime/schema"],
+    deps = [
+        "//pkg/apis/componentconfig:go_default_library",
+        "//pkg/apis/componentconfig/install:go_default_library",
+        "//vendor:k8s.io/apimachinery/pkg/runtime/schema",
+    ],
 )
 
 filegroup(

pkg/admission/config.go

@@ -0,0 +1,176 @@
+/*
+Copyright 2017 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 admission
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+	"path/filepath"
+
+	"github.com/ghodss/yaml"
+	"github.com/golang/glog"
+
+	"bytes"
+
+	"k8s.io/kubernetes/pkg/api"
+	"k8s.io/kubernetes/pkg/apis/componentconfig"
+	componentconfigv1alpha1 "k8s.io/kubernetes/pkg/apis/componentconfig/v1alpha1"
+	"k8s.io/kubernetes/pkg/util/sets"
+
+	runtime "k8s.io/apimachinery/pkg/runtime"
+)
+
+func makeAbs(path, base string) (string, error) {
+	if filepath.IsAbs(path) {
+		return path, nil
+	}
+	if len(base) == 0 || base == "." {
+		cwd, err := os.Getwd()
+		if err != nil {
+			return "", err
+		}
+		base = cwd
+	}
+	return filepath.Join(base, path), nil
+}
+
+// ReadAdmissionConfiguration reads the admission configuration at the specified path.
+// It returns the loaded admission configuration if the input file aligns with the required syntax.
+// If it does not align with the provided syntax, it returns a default configuration for the enumerated
+// set of pluginNames whose config location references the specified configFilePath.
+// It does this to preserve backward compatibility when admission control files were opaque.
+// It returns an error if the file did not exist.
+func ReadAdmissionConfiguration(pluginNames []string, configFilePath string) (*componentconfig.AdmissionConfiguration, error) {
+	if configFilePath == "" {
+		return &componentconfig.AdmissionConfiguration{}, nil
+	}
+	// a file was provided, so we just read it.
+	data, err := ioutil.ReadFile(configFilePath)
+	if err != nil {
+		return nil, fmt.Errorf("unable to read admission control configuration from %q [%v]", configFilePath, err)
+	}
+	decoder := api.Codecs.UniversalDecoder()
+	decodedObj, err := runtime.Decode(decoder, data)
+	// we were able to decode the file successfully
+	if err == nil {
+		decodedConfig, ok := decodedObj.(*componentconfig.AdmissionConfiguration)
+		if !ok {
+			return nil, fmt.Errorf("unexpected type: %T", decodedObj)
+		}
+		baseDir := path.Dir(configFilePath)
+		for i := range decodedConfig.Plugins {
+			if decodedConfig.Plugins[i].Path == "" {
+				continue
+			}
+			// we update relative file paths to absolute paths
+			absPath, err := makeAbs(decodedConfig.Plugins[i].Path, baseDir)
+			if err != nil {
+				return nil, err
+			}
+			decodedConfig.Plugins[i].Path = absPath
+		}
+		return decodedConfig, nil
+	}
+	// we got an error where the decode wasn't related to a missing type
+	if !(runtime.IsMissingVersion(err) || runtime.IsMissingKind(err) || runtime.IsNotRegisteredError(err)) {
+		return nil, err
+	}
+	// convert the legacy format to the new admission control format
+	// in order to preserve backwards compatibility, we set plugins that
+	// previously read input from a non-versioned file configuration to the
+	// current input file.
+	legacyPluginsWithUnversionedConfig := sets.NewString("ImagePolicyWebhook", "PodNodeSelector")
+	externalConfig := &componentconfigv1alpha1.AdmissionConfiguration{}
+	for _, pluginName := range pluginNames {
+		if legacyPluginsWithUnversionedConfig.Has(pluginName) {
+			externalConfig.Plugins = append(externalConfig.Plugins,
+				componentconfigv1alpha1.AdmissionPluginConfiguration{
+					Name: pluginName,
+					Path: configFilePath})
+		}
+	}
+	api.Scheme.Default(externalConfig)
+	internalConfig := &componentconfig.AdmissionConfiguration{}
+	if err := api.Scheme.Convert(externalConfig, internalConfig, nil); err != nil {
+		return internalConfig, err
+	}
+	return internalConfig, nil
+}
+
+// GetAdmissionPluginConfigurationFor returns a reader that holds the admission plugin configuration.
+func GetAdmissionPluginConfigurationFor(pluginCfg componentconfig.AdmissionPluginConfiguration) (io.Reader, error) {
+	// if there is nothing nested in the object, we return the named location
+	obj := pluginCfg.Configuration
+	if obj != nil {
+		// serialize the configuration and build a reader for it
+		content, err := writeYAML(obj)
+		if err != nil {
+			return nil, err
+		}
+		return bytes.NewBuffer(content), nil
+	}
+	// there is nothing nested, so we delegate to path
+	if pluginCfg.Path != "" {
+		content, err := ioutil.ReadFile(pluginCfg.Path)
+		if err != nil {
+			glog.Fatalf("Couldn't open admission plugin configuration %s: %#v", pluginCfg.Path, err)
+			return nil, err
+		}
+		return bytes.NewBuffer(content), nil
+	}
+	// there is no special config at all
+	return nil, nil
+}
+
+// GetAdmissionPluginConfiguration takes the admission configuration and returns a reader
+// for the specified plugin.  If no specific configuration is present, we return a nil reader.
+func GetAdmissionPluginConfiguration(cfg *componentconfig.AdmissionConfiguration, pluginName string) (io.Reader, error) {
+	// there is no config, so there is no potential config
+	if cfg == nil {
+		return nil, nil
+	}
+	// look for matching plugin and get configuration
+	for _, pluginCfg := range cfg.Plugins {
+		if pluginName != pluginCfg.Name {
+			continue
+		}
+		pluginConfig, err := GetAdmissionPluginConfigurationFor(pluginCfg)
+		if err != nil {
+			return nil, err
+		}
+		return pluginConfig, nil
+	}
+	// there is no registered config that matches on plugin name.
+	return nil, nil
+}
+
+// writeYAML writes the specified object to a byte array as yaml.
+func writeYAML(obj runtime.Object) ([]byte, error) {
+	json, err := runtime.Encode(api.Codecs.LegacyCodec(), obj)
+	if err != nil {
+		return nil, err
+	}
+
+	content, err := yaml.JSONToYAML(json)
+	if err != nil {
+		return nil, err
+	}
+	return content, err
+}

pkg/admission/config_test.go

@@ -0,0 +1,148 @@
+/*
+Copyright 2017 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 admission
+
+import (
+	"io/ioutil"
+	"os"
+	"reflect"
+	"testing"
+
+	"k8s.io/kubernetes/pkg/apis/componentconfig"
+	_ "k8s.io/kubernetes/pkg/apis/componentconfig/install"
+)
+
+func TestReadAdmissionConfiguration(t *testing.T) {
+	// create a place holder file to hold per test config
+	configFile, err := ioutil.TempFile("", "admission-plugin-config")
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	if err = configFile.Close(); err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	configFileName := configFile.Name()
+	// the location that will be fixed up to be relative to the test config file.
+	imagePolicyWebhookFile, err := makeAbs("image-policy-webhook.json", os.TempDir())
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	// individual test scenarios
+	testCases := map[string]struct {
+		ConfigBody              string
+		ExpectedAdmissionConfig *componentconfig.AdmissionConfiguration
+		PluginNames             []string
+	}{
+		"v1Alpha1 configuration - path fixup": {
+			ConfigBody: `{
+"apiVersion": "componentconfig/v1alpha1",
+"kind": "AdmissionConfiguration",
+"plugins": [
+  {"name": "ImagePolicyWebhook", "path": "image-policy-webhook.json"},
+  {"name": "ResourceQuota"}
+]}`,
+			ExpectedAdmissionConfig: &componentconfig.AdmissionConfiguration{
+				Plugins: []componentconfig.AdmissionPluginConfiguration{
+					{
+						Name: "ImagePolicyWebhook",
+						Path: imagePolicyWebhookFile,
+					},
+					{
+						Name: "ResourceQuota",
+					},
+				},
+			},
+			PluginNames: []string{},
+		},
+		"v1Alpha1 configuration - abspath": {
+			ConfigBody: `{
+"apiVersion": "componentconfig/v1alpha1",
+"kind": "AdmissionConfiguration",
+"plugins": [
+  {"name": "ImagePolicyWebhook", "path": "/tmp/image-policy-webhook.json"},
+  {"name": "ResourceQuota"}
+]}`,
+			ExpectedAdmissionConfig: &componentconfig.AdmissionConfiguration{
+				Plugins: []componentconfig.AdmissionPluginConfiguration{
+					{
+						Name: "ImagePolicyWebhook",
+						Path: "/tmp/image-policy-webhook.json",
+					},
+					{
+						Name: "ResourceQuota",
+					},
+				},
+			},
+			PluginNames: []string{},
+		},
+		"legacy configuration with using legacy plugins": {
+			ConfigBody: `{
+"imagePolicy": {
+  "kubeConfigFile": "/home/user/.kube/config",
+  "allowTTL": 30,
+  "denyTTL": 30,
+  "retryBackoff": 500,
+  "defaultAllow": true
+},
+"podNodeSelectorPluginConfig": {
+  "clusterDefaultNodeSelector": ""
+}  
+}`,
+			ExpectedAdmissionConfig: &componentconfig.AdmissionConfiguration{
+				Plugins: []componentconfig.AdmissionPluginConfiguration{
+					{
+						Name: "ImagePolicyWebhook",
+						Path: configFileName,
+					},
+					{
+						Name: "PodNodeSelector",
+						Path: configFileName,
+					},
+				},
+			},
+			PluginNames: []string{"ImagePolicyWebhook", "PodNodeSelector"},
+		},
+		"legacy configuration not using legacy plugins": {
+			ConfigBody: `{
+"imagePolicy": {
+  "kubeConfigFile": "/home/user/.kube/config",
+  "allowTTL": 30,
+  "denyTTL": 30,
+  "retryBackoff": 500,
+  "defaultAllow": true
+},
+"podNodeSelectorPluginConfig": {
+  "clusterDefaultNodeSelector": ""
+}  
+}`,
+			ExpectedAdmissionConfig: &componentconfig.AdmissionConfiguration{},
+			PluginNames:             []string{"NamespaceLifecycle", "InitialResources"},
+		},
+	}
+	for testName, testCase := range testCases {
+		if err = ioutil.WriteFile(configFileName, []byte(testCase.ConfigBody), 0644); err != nil {
+			t.Fatalf("unexpected err writing temp file: %v", err)
+		}
+		config, err := ReadAdmissionConfiguration(testCase.PluginNames, configFileName)
+		if err != nil {
+			t.Fatalf("unexpected err: %v", err)
+		}
+		if !reflect.DeepEqual(config, testCase.ExpectedAdmissionConfig) {
+			t.Errorf("%s: Expected:\n\t%#v\nGot:\n\t%#v", testName, testCase.ExpectedAdmissionConfig, config)
+		}
+	}
+}

pkg/admission/plugins.go

@@ -21,7 +21,6 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"reflect"
 	"sort"
 	"sync"
@@ -115,9 +114,20 @@ func splitStream(config io.Reader) (io.Reader, io.Reader, error) {
 // NewFromPlugins returns an admission.Interface that will enforce admission control decisions of all
 // the given plugins.
 func NewFromPlugins(pluginNames []string, configFilePath string, pluginInitializer PluginInitializer) (Interface, error) {
+	// load config file path into a componentconfig.AdmissionConfiguration
+	admissionCfg, err := ReadAdmissionConfiguration(pluginNames, configFilePath)
+	if err != nil {
+		return nil, err
+	}
+
 	plugins := []Interface{}
 	for _, pluginName := range pluginNames {
-		plugin, err := InitPlugin(pluginName, configFilePath, pluginInitializer)
+		pluginConfig, err := GetAdmissionPluginConfiguration(admissionCfg, pluginName)
+		if err != nil {
+			return nil, err
+		}
+
+		plugin, err := InitPlugin(pluginName, pluginConfig, pluginInitializer)
 		if err != nil {
 			return nil, err
 		}
@@ -129,27 +139,12 @@ func NewFromPlugins(pluginNames []string, configFilePath string, pluginInitializ
 }
 
 // InitPlugin creates an instance of the named interface.
-func InitPlugin(name string, configFilePath string, pluginInitializer PluginInitializer) (Interface, error) {
-	var (
-		config *os.File
-		err    error
-	)
-
+func InitPlugin(name string, config io.Reader, pluginInitializer PluginInitializer) (Interface, error) {
 	if name == "" {
 		glog.Info("No admission plugin specified.")
 		return nil, nil
 	}
 
-	if configFilePath != "" {
-		config, err = os.Open(configFilePath)
-		if err != nil {
-			glog.Fatalf("Couldn't open admission plugin configuration %s: %#v",
-				configFilePath, err)
-		}
-
-		defer config.Close()
-	}
-
 	plugin, found, err := getPlugin(name, config)
 	if err != nil {
 		return nil, fmt.Errorf("Couldn't init admission plugin %q: %v", name, err)

plugin/pkg/admission/imagepolicy/admission.go

@@ -214,6 +214,7 @@ func (a *imagePolicyWebhook) admitPod(attributes admission.Attributes, review *v
 // For additional HTTP configuration, refer to the kubeconfig documentation
 // http://kubernetes.io/v1.1/docs/user-guide/kubeconfig-file.html.
 func NewImagePolicyWebhook(configFile io.Reader) (admission.Interface, error) {
+	// TODO: move this to a versioned configuration file format
 	var config AdmissionConfig
 	d := yaml.NewYAMLOrJSONDecoder(configFile, 4096)
 	err := d.Decode(&config)

plugin/pkg/admission/initialresources/admission.go

@@ -47,6 +47,7 @@ const (
 // WARNING: this feature is experimental and will definitely change.
 func init() {
 	admission.RegisterPlugin("InitialResources", func(config io.Reader) (admission.Interface, error) {
+		// TODO: remove the usage of flags in favor of reading versioned configuration
 		s, err := newDataSource(*source)
 		if err != nil {
 			return nil, err

plugin/pkg/admission/podnodeselector/admission.go

@@ -41,6 +41,7 @@ var NamespaceNodeSelectors = []string{"scheduler.alpha.kubernetes.io/node-select
 
 func init() {
 	admission.RegisterPlugin("PodNodeSelector", func(config io.Reader) (admission.Interface, error) {
+		// TODO move this to a versioned configuration file format.
 		pluginConfig := readConfig(config)
 		plugin := NewPodNodeSelector(pluginConfig.PodNodeSelectorPluginConfig)
 		return plugin, nil