rebase: update kubernetes to 1.28.0 in main

updating kubernetes to 1.28.0
in the main repo.

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

vendor/k8s.io/apiserver/pkg/cel/environment/environment.go

@@ -0,0 +1,274 @@
+/*
+Copyright 2023 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 environment
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/google/cel-go/cel"
+
+	"k8s.io/apimachinery/pkg/util/version"
+	apiservercel "k8s.io/apiserver/pkg/cel"
+)
+
+// Type defines the different types of CEL environments used in Kubernetes.
+// CEL environments are used to compile and evaluate CEL expressions.
+// Environments include:
+//   - Function libraries
+//   - Variables
+//   - Types (both core CEL types and Kubernetes types)
+//   - Other CEL environment and program options
+type Type string
+
+const (
+	// NewExpressions is used to validate new or modified expressions in
+	// requests that write expressions to API resources.
+	//
+	// This environment type is compatible with a specific Kubernetes
+	// major/minor version. To ensure safe rollback, this environment type
+	// may not include all the function libraries, variables, type declarations, and CEL
+	// language settings available in the StoredExpressions environment type.
+	//
+	// NewExpressions must be used to validate (parse, compile, type check)
+	// all new or modified CEL expressions before they are written to storage.
+	NewExpressions Type = "NewExpressions"
+
+	// StoredExpressions is used to compile and run CEL expressions that have been
+	// persisted to storage.
+	//
+	// This environment type is compatible with CEL expressions that have been
+	// persisted to storage by all known versions of Kubernetes. This is the most
+	// permissive environment available.
+	//
+	// StoredExpressions is appropriate for use with CEL expressions in
+	// configuration files.
+	StoredExpressions Type = "StoredExpressions"
+)
+
+// EnvSet manages the creation and extension of CEL environments. Each EnvSet contains
+// both an NewExpressions and StoredExpressions environment. EnvSets are created
+// and extended using VersionedOptions so that the EnvSet can prepare environments according
+// to what options were introduced at which versions.
+//
+// Each EnvSet is given a compatibility version when it is created, and prepares the
+// NewExpressions environment to be compatible with that version. The EnvSet also
+// prepares StoredExpressions to be compatible with all known versions of Kubernetes.
+type EnvSet struct {
+	// compatibilityVersion is the version that all configuration in
+	// the NewExpressions environment is compatible with.
+	compatibilityVersion *version.Version
+
+	// newExpressions is an environment containing only configuration
+	// in this EnvSet that is enabled at this compatibilityVersion.
+	newExpressions *cel.Env
+
+	// storedExpressions is an environment containing the latest configuration
+	// in this EnvSet.
+	storedExpressions *cel.Env
+}
+
+func newEnvSet(compatibilityVersion *version.Version, opts []VersionedOptions) (*EnvSet, error) {
+	base, err := cel.NewEnv()
+	if err != nil {
+		return nil, err
+	}
+	baseSet := EnvSet{compatibilityVersion: compatibilityVersion, newExpressions: base, storedExpressions: base}
+	return baseSet.Extend(opts...)
+}
+
+func mustNewEnvSet(ver *version.Version, opts []VersionedOptions) *EnvSet {
+	envSet, err := newEnvSet(ver, opts)
+	if err != nil {
+		panic(fmt.Sprintf("Default environment misconfigured: %v", err))
+	}
+	return envSet
+}
+
+// NewExpressionsEnv returns the NewExpressions environment Type for this EnvSet.
+// See NewExpressions for details.
+func (e *EnvSet) NewExpressionsEnv() *cel.Env {
+	return e.newExpressions
+}
+
+// StoredExpressionsEnv returns the StoredExpressions environment Type for this EnvSet.
+// See StoredExpressions for details.
+func (e *EnvSet) StoredExpressionsEnv() *cel.Env {
+	return e.storedExpressions
+}
+
+// Env returns the CEL environment for the given Type.
+func (e *EnvSet) Env(envType Type) (*cel.Env, error) {
+	switch envType {
+	case NewExpressions:
+		return e.newExpressions, nil
+	case StoredExpressions:
+		return e.storedExpressions, nil
+	default:
+		return nil, fmt.Errorf("unsupported environment type: %v", envType)
+	}
+}
+
+// VersionedOptions provides a set of CEL configuration options as well as the version the
+// options were introduced and, optionally, the version the options were removed.
+type VersionedOptions struct {
+	// IntroducedVersion is the version at which these options were introduced.
+	// The NewExpressions environment will only include options introduced at or before the
+	// compatibility version of the EnvSet.
+	//
+	// For example, to configure a CEL environment with an "object" variable bound to a
+	// resource kind, first create a DeclType from the groupVersionKind of the resource and then
+	// populate a VersionedOptions with the variable and the type:
+	//
+	//    schema := schemaResolver.ResolveSchema(groupVersionKind)
+	//    objectType := apiservercel.SchemaDeclType(schema, true)
+	//    ...
+	//    VersionOptions{
+	//      IntroducedVersion: version.MajorMinor(1, 26),
+	//      DeclTypes: []*apiservercel.DeclType{ objectType },
+	//      EnvOptions: []cel.EnvOption{ cel.Variable("object", objectType.CelType()) },
+	//    },
+	//
+	// To create an DeclType from a CRD, use a structural schema. For example:
+	//
+	//    schema := structuralschema.NewStructural(crdJSONProps)
+	//    objectType := apiservercel.SchemaDeclType(schema, true)
+	//
+	// Required.
+	IntroducedVersion *version.Version
+	// RemovedVersion is the version at which these options were removed.
+	// The NewExpressions environment will not include options removed at or before the
+	// compatibility version of the EnvSet.
+	//
+	// All option removals must be backward compatible; the removal must either be paired
+	// with a compatible replacement introduced at the same version, or the removal must be non-breaking.
+	// The StoredExpressions environment will not include removed options.
+	//
+	// A function library may be upgraded by setting the RemovedVersion of the old library
+	// to the same value as the IntroducedVersion of the new library. The new library must
+	// be backward compatible with the old library.
+	//
+	// For example:
+	//
+	//    VersionOptions{
+	//      IntroducedVersion: version.MajorMinor(1, 26), RemovedVersion: version.MajorMinor(1, 27),
+	//      EnvOptions: []cel.EnvOption{ libraries.Example(libraries.ExampleVersion(1)) },
+	//    },
+	//    VersionOptions{
+	//      IntroducedVersion: version.MajorMinor(1, 27),
+	//      EnvOptions: []EnvOptions{ libraries.Example(libraries.ExampleVersion(2)) },
+	//    },
+	//
+	// Optional.
+	RemovedVersion *version.Version
+
+	// EnvOptions provides CEL EnvOptions. This may be used to add a cel.Variable, a
+	// cel.Library, or to enable other CEL EnvOptions such as language settings.
+	//
+	// If an added cel.Variable has an OpenAPI type, the type must be included in DeclTypes.
+	EnvOptions []cel.EnvOption
+	// ProgramOptions provides CEL ProgramOptions. This may be used to set a cel.CostLimit,
+	// enable optimizations, and set other program level options that should be enabled
+	// for all programs using this environment.
+	ProgramOptions []cel.ProgramOption
+	// DeclTypes provides OpenAPI type declarations to register with the environment.
+	//
+	// If cel.Variables added to EnvOptions refer to a OpenAPI type, the type must be included in
+	// DeclTypes.
+	DeclTypes []*apiservercel.DeclType
+}
+
+// Extend returns an EnvSet based on this EnvSet but extended with given VersionedOptions.
+// This EnvSet is not mutated.
+// The returned EnvSet has the same compatibility version as the EnvSet that was extended.
+//
+// Extend is an expensive operation and each call to Extend that adds DeclTypes increases
+// the depth of a chain of resolvers. For these reasons, calls to Extend should be kept
+// to a minimum.
+//
+// Some best practices:
+//
+//   - Minimize calls Extend when handling API requests. Where possible, call Extend
+//     when initializing components.
+//   - If an EnvSets returned by Extend can be used to compile multiple CEL programs,
+//     call Extend once and reuse the returned EnvSets.
+//   - Prefer a single call to Extend with a full list of VersionedOptions over
+//     making multiple calls to Extend.
+func (e *EnvSet) Extend(options ...VersionedOptions) (*EnvSet, error) {
+	if len(options) > 0 {
+		newExprOpts, err := e.filterAndBuildOpts(e.newExpressions, e.compatibilityVersion, options)
+		if err != nil {
+			return nil, err
+		}
+		p, err := e.newExpressions.Extend(newExprOpts)
+		if err != nil {
+			return nil, err
+		}
+		storedExprOpt, err := e.filterAndBuildOpts(e.storedExpressions, version.MajorMinor(math.MaxUint, math.MaxUint), options)
+		if err != nil {
+			return nil, err
+		}
+		s, err := e.storedExpressions.Extend(storedExprOpt)
+		if err != nil {
+			return nil, err
+		}
+		return &EnvSet{compatibilityVersion: e.compatibilityVersion, newExpressions: p, storedExpressions: s}, nil
+	}
+	return e, nil
+}
+
+func (e *EnvSet) filterAndBuildOpts(base *cel.Env, compatVer *version.Version, opts []VersionedOptions) (cel.EnvOption, error) {
+	var envOpts []cel.EnvOption
+	var progOpts []cel.ProgramOption
+	var declTypes []*apiservercel.DeclType
+
+	for _, opt := range opts {
+		if compatVer.AtLeast(opt.IntroducedVersion) && (opt.RemovedVersion == nil || compatVer.LessThan(opt.RemovedVersion)) {
+			envOpts = append(envOpts, opt.EnvOptions...)
+			progOpts = append(progOpts, opt.ProgramOptions...)
+			declTypes = append(declTypes, opt.DeclTypes...)
+		}
+	}
+
+	if len(declTypes) > 0 {
+		provider := apiservercel.NewDeclTypeProvider(declTypes...)
+		providerOpts, err := provider.EnvOptions(base.TypeProvider())
+		if err != nil {
+			return nil, err
+		}
+		envOpts = append(envOpts, providerOpts...)
+	}
+
+	combined := cel.Lib(&envLoader{
+		envOpts:  envOpts,
+		progOpts: progOpts,
+	})
+	return combined, nil
+}
+
+type envLoader struct {
+	envOpts  []cel.EnvOption
+	progOpts []cel.ProgramOption
+}
+
+func (e *envLoader) CompileOptions() []cel.EnvOption {
+	return e.envOpts
+}
+
+func (e *envLoader) ProgramOptions() []cel.ProgramOption {
+	return e.progOpts
+}