codelab/codelab.go - external/github.com/google/cel-go - Git at Google


 // Copyright 2020 Google LLC
 //
 // 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.

 // This file contains code that demonstrates common CEL features.
 // This code is intended for use with the CEL Codelab: go/cel-codelab-go
 package main

 import (
 	"encoding/json"
 	"fmt"
 	"reflect"
 	"sort"
 	"strings"
 	"time"

 	"github.com/golang/glog"
 	"github.com/golang/protobuf/jsonpb"
 	"github.com/golang/protobuf/proto"

 	"github.com/google/cel-go/cel"
 	_ "github.com/google/cel-go/checker/decls"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
 	"github.com/google/cel-go/common/types/traits"
 	_ "github.com/google/cel-go/interpreter/functions"

 	structpb "github.com/golang/protobuf/ptypes/struct"
 	tpb "github.com/golang/protobuf/ptypes/timestamp"

 	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
 	rpcpb "google.golang.org/genproto/googleapis/rpc/context/attribute_context"
 )

 func main() {
 	exercise1()
 	exercise2()
 	exercise3()
 	exercise4()
 	exercise5()
 	exercise6()
 	exercise7()
 	exercise8()
 }

 // exercise1 evaluates a simple literal expression: "Hello, World!"
 //
 // Compile, eval, profit!
 func exercise1() {
 	fmt.Println("=== Exercise 1: Hello World ===\n")

 	fmt.Println()
 }

 // exercise2 shows how to declare and use variables in expressions.
 //
 // Given a `request` of type `google.rpc.context.AttributeContext.Request`
 // determine whether a specific auth claim is set.
 func exercise2() {
 	fmt.Println("=== Exercise 2: Variables ===\n")

 	fmt.Println()
 }

 // exercise3 demonstrates how CEL's commutative logical operators work.
 //
 // Construct an expression which checks whether the `request.auth.claims.group`
 // value is equal to `admin` or the `request.auth.principal` is
 // `user:me@acme.co` and the `request.time` is during work hours (9:00 - 17:00)
 //
 // Evaluate the expression once with a request containing no claims but which
 // sets the appropriate principal and occurs at 12:00 hours. Then evaluate the
 // request a second time at midnight. Observe the difference in output.
 func exercise3() {
 	fmt.Println("=== Exercise 3: Logical AND/OR ===\n")

 	fmt.Println()
 }

 // exercise4 demonstrates how to extend CEL with custom functions.
 //
 // Declare a `contains` member function on map types that returns a boolean
 // indicating whether the map contains the key-value pair.
 func exercise4() {
 	fmt.Println("=== Exercise 4: Customization ===\n")

 	fmt.Println()
 }

 // exercise5 covers how to build complex objects as CEL literals.
 //
 // Given the input `now`, construct a JWT with an expiry of 5 minutes.
 func exercise5() {
 	fmt.Println("=== Exercise 5: Building JSON ===\n")

 	fmt.Println()
 }

 // exercise6 describes how to build proto message types within CEL.
 //
 // Given an input `jwt` and time `now` construct a
 // `google.rpc.context.AttributeContext.Request` with the `time` and `auth`
 // fields populated according to the go/api-attributes specification.
 func exercise6() {
 	fmt.Println("=== Exercise 6: Building Protos ===\n")

 	fmt.Println()
 }

 // exercise7 introduces macros for dealing with repeated fields and maps.
 //
 // Determine whether the `jwt.extra_claims` has at least one key that starts
 // with the `group` prefix, and ensure that all group-like keys have list
 // values containing only strings that end with '@acme.co`.
 func exercise7() {
 	fmt.Println("=== Exercise 7: Macros ===\n")

 	fmt.Println()
 }

 // exercise8 covers some useful features of CEL-Go which can be used to
 // improve performance and better understand evaluation behavior.
 //
 // Turn on the optimization, exhaustive eval, and state tracking
 // `cel.ProgramOption` flags to see the impact on evaluation behavior.
 //
 // Also, turn on the homogeneous aggregate literals flag to disable
 // heterogeneous list and map literals.
 func exercise8() {
 	fmt.Println("=== Exercise 8: Tuning ===\n")

 	fmt.Println()
 }

 // Functions to assist with CEL execution.

 // compile will parse and check an expression `expr` against a given
 // environment `env` and determine whether the resulting type of the expression
 // matches the `exprType` provided as input.
 func compile(env *cel.Env, expr string, exprType *exprpb.Type) *cel.Ast {
 	ast, iss := env.Compile(expr)
 	if iss.Err() != nil {
 		glog.Exit(iss.Err())
 	}
 	if !proto.Equal(ast.ResultType(), exprType) {
 		glog.Exitf(
 			"Got %v, wanted %v result type", ast.ResultType(), exprType)
 	}
 	fmt.Printf("%s\n\n", strings.ReplaceAll(expr, "\t", " "))
 	return ast
 }

 // eval will evaluate a given program `prg` against a set of variables `vars`
 // and return the output, eval details (optional), or error that results from
 // evaluation.
 func eval(prg cel.Program,
 	vars interface{}) (out ref.Val, det *cel.EvalDetails, err error) {
 	varMap, isMap := vars.(map[string]interface{})
 	fmt.Println("------ input ------")
 	if !isMap {
 		fmt.Printf("(%T)\n", vars)
 	} else {
 		for k, v := range varMap {
 			switch val := v.(type) {
 			case proto.Message:
 				fmt.Printf("%s = %v", k, proto.MarshalTextString(val))
 			case map[string]interface{}:
 				b, _ := json.MarshalIndent(v, "", "  ")
 				fmt.Printf("%s = %v\n", k, string(b))
 			case uint64:
 				fmt.Printf("%s = %vu\n", k, v)
 			default:
 				fmt.Printf("%s = %v\n", k, v)
 			}
 		}
 	}
 	fmt.Println()
 	out, det, err = prg.Eval(vars)
 	report(out, det, err)
 	fmt.Println()
 	return
 }

 // report prints out the result of evaluation in human-friendly terms.
 func report(result ref.Val, details *cel.EvalDetails, err error) {
 	fmt.Println("------ result ------")
 	if err != nil {
 		fmt.Printf("error: %s\n", err)
 	} else {
 		fmt.Printf("value: %v (%T)\n", result, result)
 	}
 	if details != nil {
 		fmt.Printf("\n------ eval states ------\n")
 		state := details.State()
 		stateIDs := state.IDs()
 		ids := make([]int, len(stateIDs), len(stateIDs))
 		for i, id := range stateIDs {
 			ids[i] = int(id)
 		}
 		sort.Ints(ids)
 		for _, id := range ids {
 			v, found := state.Value(int64(id))
 			if !found {
 				continue
 			}
 			fmt.Printf("%d: %v (%T)\n", id, v, v)
 		}
 	}
 }

 // mapContainsKeyValue implements the custom function:
 //   `map.contains(key, value) bool`.
 func mapContainsKeyValue(args ...ref.Val) ref.Val {
 	// Check the argument input count.
 	if len(args) != 3 {
 		return types.NewErr("no such overload")
 	}
 	obj := args[0]
 	m, isMap := obj.(traits.Mapper)
 	// Ensure the argument is a CEL map type, otherwise error.
 	// The type-checking is a best effort check to ensure that the types provided
 	// to functions match the ones specified; however, it is always possible that
 	// the implementation does not match the declaration. Always check arguments
 	// types whenever there is a possibility that your function will deal with
 	// dynamic content.
 	if !isMap {
 		// The helper ValOrErr ensures that errors on input are propagated.
 		return types.ValOrErr(obj, "no such overload")
 	}

 	// CEL has many interfaces for dealing with different type abstractions.
 	// The traits.Mapper interface unifies field presence testing on proto
 	// messages and maps.
 	key := args[1]
 	v, found := m.Find(key)
 	// If not found and the value was non-nil, the value is an error per the
 	// `Find` contract. Propagate it accordingly.
 	if !found {
 		if v != nil {
 			return types.ValOrErr(v, "unsupported key type")
 		}
 		// Return CEL False if the key was not found.
 		return types.False
 	}
 	// Otherwise whether the value at the key equals the value provided.
 	return v.Equal(args[2])
 }

 // Functions for constructing CEL inputs.

 // auth constructs a `google.rpc.context.AttributeContext.Auth` message.
 func auth(user string, claims map[string]string) *rpcpb.AttributeContext_Auth {
 	claimFields := make(map[string]*structpb.Value)
 	for k, v := range claims {
 		claimFields[k] = &structpb.Value{
 			Kind: &structpb.Value_StringValue{
 				StringValue: v,
 			},
 		}
 	}
 	return &rpcpb.AttributeContext_Auth{
 		Principal: user,
 		Claims:    &structpb.Struct{Fields: claimFields},
 	}
 }

 // request constructs a `google.rpc.context.AttributeContext.Request` message.
 func request(auth *rpcpb.AttributeContext_Auth, t time.Time) map[string]interface{} {
 	req := &rpcpb.AttributeContext_Request{
 		Auth: auth,
 		Time: &tpb.Timestamp{Seconds: t.Unix()},
 	}
 	return map[string]interface{}{"request": req}
 }

 // valueToJSON converts the CEL type to a protobuf JSON representation and
 // marshals the result to a string.
 func valueToJSON(val ref.Val) string {
 	v, err := val.ConvertToNative(reflect.TypeOf(&structpb.Value{}))
 	if err != nil {
 		glog.Exit(err)
 	}
 	marshaller := &jsonpb.Marshaler{Indent: "    "}
 	str, err := marshaller.MarshalToString(v.(proto.Message))
 	if err != nil {
 		glog.Exit(err)
 	}
 	return str
 }

 var (
 	emptyClaims = make(map[string]string)
 )

	// Copyright 2020 Google LLC
	//
	// 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.

	// This file contains code that demonstrates common CEL features.
	// This code is intended for use with the CEL Codelab: go/cel-codelab-go
	package main

	import (
	"encoding/json"
	"fmt"
	"reflect"
	"sort"
	"strings"
	"time"

	"github.com/golang/glog"
	"github.com/golang/protobuf/jsonpb"
	"github.com/golang/protobuf/proto"

	"github.com/google/cel-go/cel"
	_ "github.com/google/cel-go/checker/decls"
	"github.com/google/cel-go/common/types"
	"github.com/google/cel-go/common/types/ref"
	"github.com/google/cel-go/common/types/traits"
	_ "github.com/google/cel-go/interpreter/functions"

	structpb "github.com/golang/protobuf/ptypes/struct"
	tpb "github.com/golang/protobuf/ptypes/timestamp"

	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
	rpcpb "google.golang.org/genproto/googleapis/rpc/context/attribute_context"
	)

	func main() {
	exercise1()
	exercise2()
	exercise3()
	exercise4()
	exercise5()
	exercise6()
	exercise7()
	exercise8()
	}

	// exercise1 evaluates a simple literal expression: "Hello, World!"
	//
	// Compile, eval, profit!
	func exercise1() {
	fmt.Println("=== Exercise 1: Hello World ===\n")

	fmt.Println()
	}

	// exercise2 shows how to declare and use variables in expressions.
	//
	// Given a `request` of type `google.rpc.context.AttributeContext.Request`
	// determine whether a specific auth claim is set.
	func exercise2() {
	fmt.Println("=== Exercise 2: Variables ===\n")

	fmt.Println()
	}

	// exercise3 demonstrates how CEL's commutative logical operators work.
	//
	// Construct an expression which checks whether the `request.auth.claims.group`
	// value is equal to `admin` or the `request.auth.principal` is
	// `user:me@acme.co` and the `request.time` is during work hours (9:00 - 17:00)
	//
	// Evaluate the expression once with a request containing no claims but which
	// sets the appropriate principal and occurs at 12:00 hours. Then evaluate the
	// request a second time at midnight. Observe the difference in output.
	func exercise3() {
	fmt.Println("=== Exercise 3: Logical AND/OR ===\n")

	fmt.Println()
	}

	// exercise4 demonstrates how to extend CEL with custom functions.
	//
	// Declare a `contains` member function on map types that returns a boolean
	// indicating whether the map contains the key-value pair.
	func exercise4() {
	fmt.Println("=== Exercise 4: Customization ===\n")

	fmt.Println()
	}

	// exercise5 covers how to build complex objects as CEL literals.
	//
	// Given the input `now`, construct a JWT with an expiry of 5 minutes.
	func exercise5() {
	fmt.Println("=== Exercise 5: Building JSON ===\n")

	fmt.Println()
	}

	// exercise6 describes how to build proto message types within CEL.
	//
	// Given an input `jwt` and time `now` construct a
	// `google.rpc.context.AttributeContext.Request` with the `time` and `auth`
	// fields populated according to the go/api-attributes specification.
	func exercise6() {
	fmt.Println("=== Exercise 6: Building Protos ===\n")

	fmt.Println()
	}

	// exercise7 introduces macros for dealing with repeated fields and maps.
	//
	// Determine whether the `jwt.extra_claims` has at least one key that starts
	// with the `group` prefix, and ensure that all group-like keys have list
	// values containing only strings that end with '@acme.co`.
	func exercise7() {
	fmt.Println("=== Exercise 7: Macros ===\n")

	fmt.Println()
	}

	// exercise8 covers some useful features of CEL-Go which can be used to
	// improve performance and better understand evaluation behavior.
	//
	// Turn on the optimization, exhaustive eval, and state tracking
	// `cel.ProgramOption` flags to see the impact on evaluation behavior.
	//
	// Also, turn on the homogeneous aggregate literals flag to disable
	// heterogeneous list and map literals.
	func exercise8() {
	fmt.Println("=== Exercise 8: Tuning ===\n")

	fmt.Println()
	}

	// Functions to assist with CEL execution.

	// compile will parse and check an expression `expr` against a given
	// environment `env` and determine whether the resulting type of the expression
	// matches the `exprType` provided as input.
	func compile(env cel.Env, expr string, exprType exprpb.Type) *cel.Ast {
	ast, iss := env.Compile(expr)
	if iss.Err() != nil {
	glog.Exit(iss.Err())
	}
	if !proto.Equal(ast.ResultType(), exprType) {
	glog.Exitf(
	"Got %v, wanted %v result type", ast.ResultType(), exprType)
	}
	fmt.Printf("%s\n\n", strings.ReplaceAll(expr, "\t", " "))
	return ast
	}

	// eval will evaluate a given program `prg` against a set of variables `vars`
	// and return the output, eval details (optional), or error that results from
	// evaluation.
	func eval(prg cel.Program,
	vars interface{}) (out ref.Val, det *cel.EvalDetails, err error) {
	varMap, isMap := vars.(map[string]interface{})
	fmt.Println("------ input ------")
	if !isMap {
	fmt.Printf("(%T)\n", vars)
	} else {
	for k, v := range varMap {
	switch val := v.(type) {
	case proto.Message:
	fmt.Printf("%s = %v", k, proto.MarshalTextString(val))
	case map[string]interface{}:
	b, _ := json.MarshalIndent(v, "", " ")
	fmt.Printf("%s = %v\n", k, string(b))
	case uint64:
	fmt.Printf("%s = %vu\n", k, v)
	default:
	fmt.Printf("%s = %v\n", k, v)
	}
	}
	}
	fmt.Println()
	out, det, err = prg.Eval(vars)
	report(out, det, err)
	fmt.Println()
	return
	}

	// report prints out the result of evaluation in human-friendly terms.
	func report(result ref.Val, details *cel.EvalDetails, err error) {
	fmt.Println("------ result ------")
	if err != nil {
	fmt.Printf("error: %s\n", err)
	} else {
	fmt.Printf("value: %v (%T)\n", result, result)
	}
	if details != nil {
	fmt.Printf("\n------ eval states ------\n")
	state := details.State()
	stateIDs := state.IDs()
	ids := make([]int, len(stateIDs), len(stateIDs))
	for i, id := range stateIDs {
	ids[i] = int(id)
	}
	sort.Ints(ids)
	for _, id := range ids {
	v, found := state.Value(int64(id))
	if !found {
	continue
	}
	fmt.Printf("%d: %v (%T)\n", id, v, v)
	}
	}
	}

	// mapContainsKeyValue implements the custom function:
	// `map.contains(key, value) bool`.
	func mapContainsKeyValue(args ...ref.Val) ref.Val {
	// Check the argument input count.
	if len(args) != 3 {
	return types.NewErr("no such overload")
	}
	obj := args[0]
	m, isMap := obj.(traits.Mapper)
	// Ensure the argument is a CEL map type, otherwise error.
	// The type-checking is a best effort check to ensure that the types provided
	// to functions match the ones specified; however, it is always possible that
	// the implementation does not match the declaration. Always check arguments
	// types whenever there is a possibility that your function will deal with
	// dynamic content.
	if !isMap {
	// The helper ValOrErr ensures that errors on input are propagated.
	return types.ValOrErr(obj, "no such overload")
	}

	// CEL has many interfaces for dealing with different type abstractions.
	// The traits.Mapper interface unifies field presence testing on proto
	// messages and maps.
	key := args[1]
	v, found := m.Find(key)
	// If not found and the value was non-nil, the value is an error per the
	// `Find` contract. Propagate it accordingly.
	if !found {
	if v != nil {
	return types.ValOrErr(v, "unsupported key type")
	}
	// Return CEL False if the key was not found.
	return types.False
	}
	// Otherwise whether the value at the key equals the value provided.
	return v.Equal(args[2])
	}

	// Functions for constructing CEL inputs.

	// auth constructs a `google.rpc.context.AttributeContext.Auth` message.
	func auth(user string, claims map[string]string) *rpcpb.AttributeContext_Auth {
	claimFields := make(map[string]*structpb.Value)
	for k, v := range claims {
	claimFields[k] = &structpb.Value{
	Kind: &structpb.Value_StringValue{
	StringValue: v,
	},
	}
	}
	return &rpcpb.AttributeContext_Auth{
	Principal: user,
	Claims: &structpb.Struct{Fields: claimFields},
	}
	}

	// request constructs a `google.rpc.context.AttributeContext.Request` message.
	func request(auth *rpcpb.AttributeContext_Auth, t time.Time) map[string]interface{} {
	req := &rpcpb.AttributeContext_Request{
	Auth: auth,
	Time: &tpb.Timestamp{Seconds: t.Unix()},
	}
	return map[string]interface{}{"request": req}
	}

	// valueToJSON converts the CEL type to a protobuf JSON representation and
	// marshals the result to a string.
	func valueToJSON(val ref.Val) string {
	v, err := val.ConvertToNative(reflect.TypeOf(&structpb.Value{}))
	if err != nil {
	glog.Exit(err)
	}
	marshaller := &jsonpb.Marshaler{Indent: " "}
	str, err := marshaller.MarshalToString(v.(proto.Message))
	if err != nil {
	glog.Exit(err)
	}
	return str
	}

	var (
	emptyClaims = make(map[string]string)
	)