Merge pull request #112858 from alexzielenski/cel-admission-hook

CEL Admission Plugin

staging/src/k8s.io/apiserver/pkg/admission/plugin/cel/OWNERS

@@ -0,0 +1,10 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+  - jpbetz
+  - cici37
+  - alexzielenski
+reviewers:
+  - jpbetz
+  - cici37
+  - alexzielenski

staging/src/k8s.io/apiserver/pkg/admission/plugin/cel/admission.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2022 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 cel
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"time"
+
+	"k8s.io/apiserver/pkg/admission"
+	"k8s.io/client-go/tools/cache"
+)
+
+////////////////////////////////////////////////////////////////////////////////
+// Plugin Definition
+////////////////////////////////////////////////////////////////////////////////
+
+// Definition for CEL admission plugin. This is the entry point into the
+// CEL admission control system.
+//
+// Each plugin is asked to validate every object update.
+
+const (
+	// PluginName indicates the name of admission plug-in
+	PluginName = "CEL"
+)
+
+// Register registers a plugin
+func Register(plugins *admission.Plugins) {
+	plugins.Register(PluginName, func(config io.Reader) (admission.Interface, error) {
+		return NewPlugin()
+	})
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Plugin Initialization & Dependency Injection
+////////////////////////////////////////////////////////////////////////////////
+
+type celAdmissionPlugin struct {
+	evaluator CELPolicyEvaluator
+}
+
+var _ WantsCELPolicyEvaluator = &celAdmissionPlugin{}
+var _ admission.ValidationInterface = &celAdmissionPlugin{}
+
+func NewPlugin() (*celAdmissionPlugin, error) {
+	result := &celAdmissionPlugin{}
+	return result, nil
+}
+
+func (c *celAdmissionPlugin) SetCELPolicyEvaluator(evaluator CELPolicyEvaluator) {
+	c.evaluator = evaluator
+}
+
+// Once clientset and informer factory are provided, creates and starts the
+// admission controller
+func (c *celAdmissionPlugin) ValidateInitialization() error {
+	if c.evaluator != nil {
+		return nil
+	}
+
+	return errors.New("CELPolicyEvaluator not injected")
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// admission.ValidationInterface
+////////////////////////////////////////////////////////////////////////////////
+
+func (c *celAdmissionPlugin) Handles(operation admission.Operation) bool {
+	return true
+}
+
+func (c *celAdmissionPlugin) Validate(
+	ctx context.Context,
+	a admission.Attributes,
+	o admission.ObjectInterfaces,
+) (err error) {
+
+	deadlined, cancel := context.WithTimeout(ctx, 2*time.Second)
+	defer cancel()
+
+	if !cache.WaitForNamedCacheSync("cel-admission-plugin", deadlined.Done(), c.evaluator.HasSynced) {
+		return admission.NewForbidden(a, fmt.Errorf("not yet ready to handle request"))
+	}
+
+	return c.evaluator.Validate(ctx, a, o)
+}