Ceci est le guide du développeur du AWS CDK v2. L'ancien CDK v1 est entré en maintenance le 1er juin 2022 et a pris fin le 1er juin 2023.
Les traductions sont fournies par des outils de traduction automatique. En cas de conflit entre le contenu d'une traduction et celui de la version originale en anglais, la version anglaise prévaudra.
# Les jetons et le AWS CDK
Dans le AWS Cloud Development Kit (AWS CDK), les *jetons sont des* espaces réservés à des valeurs inconnues lors de la définition de constructions ou de la synthèse de piles. Ces valeurs seront entièrement résolues lors du déploiement, lorsque votre infrastructure réelle sera créée. Lorsque vous AWS développez des applications CDK, vous utiliserez des jetons pour gérer ces valeurs dans l'ensemble de votre application.
## Exemple de jeton
Voici un exemple de pile CDK qui définit une structure pour un bucket Amazon Simple Storage Service (Amazon S3). Le nom de notre bucket n'étant pas encore connu, la valeur de `bucketName` est stockée sous forme de jeton :
**Example**
```
import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as s3 from 'aws-cdk-lib/aws-s3';
export class CdkDemoAppStack extends cdk.Stack {
constructor(scope: Construct, id: string, props?: cdk.StackProps) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// Store value of the S3 bucket name
const myBucketName = myBucket.bucketName;
// Print the current value for the S3 bucket name at synthesis
console.log("myBucketName: " + myBucketName);
}
}
```
```
const { Stack, Duration } = require('aws-cdk-lib');
const s3 = require('aws-cdk-lib/aws-s3');
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// Store value of the S3 bucket name
const myBucketName = myBucket.bucketName;
// Print the current value for the S3 bucket name at synthesis
console.log("myBucketName: " + myBucketName);
}
}
module.exports = { CdkDemoAppStack }
```
```
from aws_cdk import (
Stack
)
from constructs import Construct
from aws_cdk import aws_s3 as s3
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define an S3 bucket
my_bucket = s3.Bucket(self, "myBucket")
# Store the value of the S3 bucket name
my_bucket_name = my_bucket.bucket_name
# Print the current value for the S3 bucket name at synthesis
print(f"myBucketName: {my_bucket_name}")
```
```
package com.myorg;
import software.constructs.Construct;
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;
import software.amazon.awscdk.services.s3.Bucket;
import java.util.Map;
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define an S3 bucket
Bucket myBucket = Bucket.Builder.create(this, "myBucket")
.build();
// Store the token for the bucket name
String myBucketName = myBucket.getBucketName();
// Print the token at synthesis
System.out.println("myBucketName: " + myBucketName);
}
}
```
```
using Amazon.CDK;
using Constructs;
using Amazon.CDK.AWS.S3;
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define an S3 bucket
var myBucket = new Bucket(this, "myBucket");
// Store the token for the bucket name
var myBucketName = myBucket.BucketName;
// Print the token at synthesis
System.Console.WriteLine($"myBucketName: {myBucketName}");
}
}
}
```
```
package main
import (
"fmt"
"github.com/aws/aws-cdk-go/awscdk/v2"
"github.com/aws/aws-cdk-go/awscdk/v2/awss3"
"github.com/aws/constructs-go/constructs/v10"
"github.com/aws/jsii-runtime-go"
)
type CdkDemoAppStackProps struct {
awscdk.StackProps
}
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define an S3 bucket
myBucket := awss3.NewBucket(stack, jsii.String("myBucket"), &awss3.BucketProps{})
// Store the token for the bucket name
myBucketName := myBucket.BucketName()
// Print the token at synthesis
fmt.Println("myBucketName: ", *myBucketName)
return stack
}
// ...
```
Lorsque nous exécutons `cdk synth` la synthèse de notre pile, la valeur de `myBucketName` sera affichée au format jeton de`${Token[TOKEN.<1234>]}`. Ce format de jeton est le résultat de la façon dont le AWS CDK code les jetons. Dans cet exemple, le jeton est codé sous forme de chaîne :
```
$ cdk synth --quiet
myBucketName: ${Token[TOKEN.21]}
```
Comme la valeur du nom de notre bucket n'est pas connue lors de la synthèse, le jeton est rendu sous la forme`myBucket`. Notre AWS CloudFormation modèle utilise la fonction `Ref` intrinsèque pour référencer sa valeur, qui sera connue lors du déploiement :
```
Resources:
myBucket<5AF9C99B>:
# ...
Outputs:
bucketNameOutput:
Description: The name of the S3 bucket
Value:
Ref: myBucket<5AF9C99B>
```
Pour plus d'informations sur la façon dont le hachage unique est généré, consultez la section [Logique générée IDs dans votre AWS CloudFormation modèle](configure-synth.md#how-synth-default-logical-ids).
## Passage de jetons
Les jetons peuvent être transmis comme s'ils étaient la valeur réelle qu'ils représentent. Voici un exemple qui transmet le jeton du nom de notre bucket à une construction pour une fonction AWS Lambda :
**Example**
```
import * as cdk from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as s3 from 'aws-cdk-lib/aws-s3';
import * as lambda from 'aws-cdk-lib/aws-lambda';
export class CdkDemoAppStack extends cdk.Stack {
constructor(scope: Construct, id: string, props?: cdk.StackProps) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// ...
// Define a Lambda function
const myFunction = new lambda.Function(this, "myFunction", {
runtime: lambda.Runtime.NODEJS_20_X,
handler: "index.handler",
code: lambda.Code.fromInline(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`),
functionName: myBucketName + "Function", // Pass token for the S3 bucket name
environment: {
BUCKET_NAME: myBucketName, // Pass token for the S3 bucket name
}
});
}
}
```
```
const { Stack, Duration } = require('aws-cdk-lib');
const s3 = require('aws-cdk-lib/aws-s3');
const lambda = require('aws-cdk-lib/aws-lambda');
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// ...
// Define a Lambda function
const myFunction = new lambda.Function(this, 'myFunction', {
runtime: lambda.Runtime.NODEJS_20_X,
handler: 'index.handler',
code: lambda.Code.fromInline(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`),
functionName: myBucketName + 'Function', // Pass token for the S3 bucket name
environment: {
BUCKET_NAME: myBucketName, // Pass token for the S3 bucket name
}
});
}
}
module.exports = { CdkDemoAppStack }
```
```
from aws_cdk import (
Stack
)
from constructs import Construct
from aws_cdk import aws_s3 as s3
from aws_cdk import aws_lambda as _lambda
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define an S3 bucket
my_bucket = s3.Bucket(self, "myBucket")
# ...
# Define a Lambda function
my_function = _lambda.Function(self, "myFunction",
runtime=_lambda.Runtime.NODEJS_20_X,
handler="index.handler",
code=_lambda.Code.from_inline("""
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
"""),
function_name=f"{my_bucket_name}Function", # Pass token for the S3 bucket name
environment={
"BUCKET_NAME": my_bucket_name # Pass token for the S3 bucket name
}
)
```
```
package com.myorg;
import software.constructs.Construct;
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;
import software.amazon.awscdk.services.s3.Bucket;
import software.amazon.awscdk.services.lambda.Code;
import software.amazon.awscdk.services.lambda.Function;
import software.amazon.awscdk.services.lambda.Runtime;
import java.util.Map;
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define an S3 bucket
Bucket myBucket = Bucket.Builder.create(this, "myBucket")
.build();
// ...
// Define a Lambda function
Function myFunction = Function.Builder.create(this, "myFunction")
.runtime(Runtime.NODEJS_20_X)
.handler("index.handler")
.code(Code.fromInline(
"exports.handler = async function(event) {" +
"return {" +
"statusCode: 200," +
"body: JSON.stringify('Hello World!')," +
"};" +
"};"
))
.functionName(myBucketName + "Function") // Pass the token for the s3 bucket to the function construct
.environment(Map.of("BUCKET_NAME", myBucketName)) // Pass the bucket name as environment variable
.build();
}
}
```
```
using Amazon.CDK;
using Constructs;
using Amazon.CDK.AWS.S3;
using Amazon.CDK.AWS.Lambda;
using System;
using System.Collections.Generic;
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define an S3 bucket
var myBucket = new Bucket(this, "myBucket");
// ...
// Define a Lambda function
var myFunction = new Function(this, "myFunction", new FunctionProps
{
Runtime = Runtime.NODEJS_20_X,
Handler = "index.handler",
Code = Code.FromInline(@"
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
"),
// Pass the token for the S3 bucket name
Environment = new Dictionary
{
{ "BUCKET_NAME", myBucketName }
},
FunctionName = $"{myBucketName}Function" // Pass the token for the s3 bucket to the function construct
});
}
}
}
```
```
package main
import (
"fmt"
"github.com/aws/aws-cdk-go/awscdk/v2"
"github.com/aws/aws-cdk-go/awscdk/v2/awslambda"
"github.com/aws/aws-cdk-go/awscdk/v2/awss3"
"github.com/aws/constructs-go/constructs/v10"
"github.com/aws/jsii-runtime-go"
)
type CdkDemoAppStackProps struct {
awscdk.StackProps
}
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define an S3 bucket
myBucket := awss3.NewBucket(stack, jsii.String("myBucket"), &awss3.BucketProps{})
// ...
// Define a Lambda function
myFunction := awslambda.NewFunction(stack, jsii.String("myFunction"), &awslambda.FunctionProps{
Runtime: awslambda.Runtime_NODEJS_20_X(),
Handler: jsii.String("index.handler"),
Code: awslambda.Code_FromInline(jsii.String(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`)),
FunctionName: jsii.String(fmt.Sprintf("%sFunction", *myBucketName)), // Pass the token for the S3 bucket to the function name
Environment: &map[string]*string{
"BUCKET_NAME": myBucketName,
},
})
return stack
}
// ...
```
Lorsque nous synthétisons notre modèle, les fonctions `Fn::Join` intrinsèques `Ref` et sont utilisées pour spécifier les valeurs, qui seront connues lors du déploiement :
```
Resources:
myBucket<5AF9C99B>:
Type: AWS::S3::Bucket
# ...
myFunction<884E1557>:
Type: AWS::Lambda::Function
Properties:
# ...
Environment:
Variables:
BUCKET_NAME:
Ref: myBucket<5AF9C99B>
FunctionName:
Fn::Join:
- ""
- - Ref: myBucket<5AF9C99B>
- Function
# ...
```
## Comment fonctionnent les encodages de jetons
Les jetons sont des objets qui implémentent l'[https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.IResolvable.html)interface, qui contient une `resolve` méthode unique. Lors de la synthèse, le AWS CDK appelle cette méthode pour produire la valeur finale des jetons dans votre CloudFormation modèle.
**Note**
Il est rare que vous travailliez directement avec l'`IResolvable`interface. Vous ne verrez probablement que des versions de jetons codées par chaîne.
### Types de codage de jetons
Les jetons participent au processus de synthèse pour produire des valeurs arbitraires de tout type. Les autres fonctions n'acceptent généralement que des arguments de type basique, tels que `string` ou`number`. Pour utiliser des jetons dans ces cas, vous pouvez les encoder dans l'un des trois types suivants en utilisant des méthodes statiques sur la [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html)classe.
+ [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrstringvalue-options](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrstringvalue-options)pour générer un codage de chaîne (ou appeler `.toString()` l'objet jeton).
+ [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrlistvalue-options](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrlistvalue-options)pour générer un codage de liste.
+ [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrnumbervalue](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-aswbrnumbervalue)pour générer un codage numérique.
Ils prennent une valeur arbitraire, qui peut être un`IResolvable`, et les encodent en une valeur primitive du type indiqué.
**Important**
Étant donné que l'un des types précédents peut potentiellement être un jeton codé, soyez prudent lorsque vous analysez ou essayez de lire leur contenu. Par exemple, si vous essayez d'analyser une chaîne pour en extraire une valeur et que la chaîne est un jeton codé, votre analyse échoue. De même, si vous essayez d'interroger la longueur d'un tableau ou d'effectuer des opérations mathématiques avec un nombre, vous devez d'abord vérifier qu'il ne s'agit pas de jetons codés.
## Comment vérifier la présence de jetons dans votre application
Pour vérifier si une valeur contient un jeton non résolu, appelez la méthode [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-iswbrunresolvedobj](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Token.html#static-iswbrunresolvedobj)(Python :`is_unresolved`). Voici un exemple qui vérifie si la valeur de notre nom de compartiment Amazon S3 est un jeton. S'il ne s'agit pas d'un jeton, nous validons ensuite la longueur du nom du bucket :
**Example**
```
// ...
export class CdkDemoAppStack extends cdk.Stack {
constructor(scope: Construct, id: string, props?: cdk.StackProps) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// ...
// Check if bucket name is a token. If not, check if length is less than 10 characters
if (cdk.Token.isUnresolved(myBucketName)) {
console.log("Token identified.");
} else if (!cdk.Token.isUnresolved(myBucketName) && myBucketName.length > 10) {
throw new Error('Maximum length for name is 10 characters.');
};
// ...
}
}
```
```
const { Stack, Duration, Token, CfnOutput } = require('aws-cdk-lib');
// ...
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define an S3 bucket
const myBucket = new s3.Bucket(this, 'myBucket');
// ...
// Check if bucket name is a token. If not, check if length is less than 10 characters
if (Token.isUnresolved(myBucketName)) {
console.log("Token identified.");
} else if (!Token.isUnresolved(myBucketName) && myBucketName.length > 10) {
throw new Error('Maximum length for name is 10 characters.');
};
// ...
}
}
```
```
from aws_cdk import (
Stack,
Token
)
# ...
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define an S3 bucket
my_bucket = s3.Bucket(self, "myBucket")
# ...
# Check if bucket name is a token. If not, check if length is less than 10 characters
if Token.is_unresolved(my_bucket_name):
print("Token identified.")
elif not Token.is_unresolved(my_bucket_name) and len(my_bucket_name) < 10:
raise ValueError("Maximum length for name is 10 characters.")
# ...
```
```
// ...
import software.amazon.awscdk.Token;
import software.amazon.awscdk.services.s3.Bucket;
// ...
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define an S3 bucket
Bucket myBucket = Bucket.Builder.create(this, "myBucket")
.build();
// ...
// Get the bucket name
String myBucketName = myBucket.getBucketName();
// Check if the bucket name is a token. If not, check if length is less than 10 characters
if (Token.isUnresolved(myBucketName)) {
System.out.println("Token identified.");
} else if (!Token.isUnresolved(myBucketName) && myBucketName.length() > 10) {
throw new IllegalArgumentException("Maximum length for name is 10 characters.");
}
// ...
}
}
}
```
```
using Amazon.CDK;
using Constructs;
using Amazon.CDK.AWS.S3;
using Amazon.CDK.AWS.Lambda;
using System;
using System.Collections.Generic;
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define an S3 bucket
var myBucket = new Bucket(this, "myBucket");
// ...
// Get the bucket name
var myBucketName = myBucket.BucketName;
// Check if bucket name is a token. If not, check if length is less than 10 characters
if (Token.IsUnresolved(myBucketName))
{
System.Console.WriteLine("Token identified.");
}
else if (!Token.IsUnresolved(myBucketName) && myBucketName.Length > 10)
{
throw new System.Exception("Maximum length for name is 10 characters.");
}
// ...
}
}
}
```
```
// ...
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define an S3 bucket
myBucket := awss3.NewBucket(stack, jsii.String("myBucket"), &awss3.BucketProps{})
// ...
// Check if the bucket name is unresolved (a token)
if tokenUnresolved := awscdk.Token_IsUnresolved(myBucketName); tokenUnresolved != nil && *tokenUnresolved {
fmt.Println("Token identified.")
} else if tokenUnresolved != nil && !*tokenUnresolved && len(*myBucketName) > 10 {
panic("Maximum length for name is 10 characters.")
}
// ...
}
```
Lorsque nous exécutons`cdk synth`, `myBucketName` est identifié comme un jeton :
```
$ cdk synth --quiet
Token identified.
```
**Note**
Vous pouvez utiliser des codages de jetons pour échapper au système de types. Par exemple, vous pouvez coder en chaîne un jeton qui produit une valeur numérique au moment de la synthèse. Si vous utilisez ces fonctions, il est de votre responsabilité de vous assurer que votre modèle passe à un état utilisable après la synthèse.
## Utilisation de jetons codés par chaîne
Les jetons codés par chaîne ressemblent à ce qui suit.
```
${TOKEN[Bucket.Name.1234]}
```
Elles peuvent être transmises comme des chaînes ordinaires et peuvent être concaténées, comme le montre l'exemple suivant.
**Example**
```
const functionName = bucket.bucketName + 'Function';
```
```
const functionName = bucket.bucketName + 'Function';
```
```
function_name = bucket.bucket_name + "Function"
```
```
String functionName = bucket.getBucketName().concat("Function");
```
```
string functionName = bucket.BucketName + "Function";
```
```
functionName := *bucket.BucketName() + "Function"
```
Vous pouvez également utiliser l'interpolation de chaînes, si votre langue le permet, comme indiqué dans l'exemple suivant.
**Example**
```
const functionName = `${bucket.bucketName}Function`;
```
```
const functionName = `${bucket.bucketName}Function`;
```
```
function_name = f"{bucket.bucket_name}Function"
```
```
String functionName = String.format("%sFunction". bucket.getBucketName());
```
```
string functionName = $"${bucket.bucketName}Function";
```
À utiliser `fmt.Sprintf` pour des fonctionnalités similaires :
```
functionName := fmt.Sprintf("%sFunction", *bucket.BucketName())
```
Évitez de manipuler la chaîne d'une autre manière. Par exemple, la prise d'une sous-chaîne d'une chaîne risque de casser le jeton de chaîne.
## Utilisation de jetons codés sous forme de liste
Les jetons codés sous forme de liste ressemblent à ce qui suit :
```
["#{TOKEN[Stack.NotificationArns.1234]}"]
```
La seule chose sûre à faire avec ces listes est de les transmettre directement à d'autres constructions. Les jetons sous forme de liste de chaînes ne peuvent pas être concaténés, et aucun élément ne peut être extrait du jeton. Le seul moyen sûr de les manipuler est d'utiliser des fonctions AWS CloudFormation intrinsèques telles que [https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-select.html](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-select.html).
## Utilisation de jetons numérotés
Les jetons codés par des nombres sont un ensemble de minuscules nombres négatifs à virgule flottante qui ressemblent à ce qui suit.
```
-1.8881545897087626e+289
```
Comme pour les jetons de liste, vous ne pouvez pas modifier la valeur numérique, car cela risque de casser le jeton numérique.
Voici un exemple de construction contenant un jeton codé sous forme de nombre :
**Example**
```
import { Stack, Duration, StackProps } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as rds from 'aws-cdk-lib/aws-rds';
import * as ec2 from 'aws-cdk-lib/aws-ec2';
export class CdkDemoAppStack extends Stack {
constructor(scope: Construct, id: string, props?: StackProps) {
super(scope, id, props);
// Define a new VPC
const vpc = new ec2.Vpc(this, 'MyVpc', {
maxAzs: 3, // Maximum number of availability zones to use
});
// Define an RDS database cluster
const dbCluster = new rds.DatabaseCluster(this, 'MyRDSCluster', {
engine: rds.DatabaseClusterEngine.AURORA,
instanceProps: {
vpc,
},
});
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// Print the value for our token at synthesis
console.log("portToken: " + portToken);
}
}
```
```
const { Stack, Duration } = require('aws-cdk-lib');
const lambda = require('aws-cdk-lib/aws-lambda');
const rds = require('aws-cdk-lib/aws-rds');
const ec2 = require('aws-cdk-lib/aws-ec2');
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define a new VPC
const vpc = new ec2.Vpc(this, 'MyVpc', {
maxAzs: 3, // Maximum number of availability zones to use
});
// Define an RDS database cluster
const dbCluster = new rds.DatabaseCluster(this, 'MyRDSCluster', {
engine: rds.DatabaseClusterEngine.AURORA,
instanceProps: {
vpc,
},
});
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// Print the value for our token at synthesis
console.log("portToken: " + portToken);
}
}
module.exports = { CdkDemoAppStack }
```
```
from aws_cdk import (
Duration,
Stack,
)
from aws_cdk import aws_rds as rds
from aws_cdk import aws_ec2 as ec2
from constructs import Construct
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define a new VPC
vpc = ec2.Vpc(self, 'MyVpc',
max_azs=3 # Maximum number of availability zones to use
)
# Define an RDS database cluster
db_cluster = rds.DatabaseCluster(self, 'MyRDSCluster',
engine=rds.DatabaseClusterEngine.AURORA,
instance_props=rds.InstanceProps(
vpc=vpc
)
)
# Get the port token (this is a token encoded as a number)
port_token = db_cluster.cluster_endpoint.port
# Print the value for our token at synthesis
print(f"portToken: {port_token}")
```
```
package com.myorg;
import software.constructs.Construct;
import software.amazon.awscdk.Stack;
import software.amazon.awscdk.StackProps;
import software.amazon.awscdk.services.ec2.Vpc;
import software.amazon.awscdk.services.rds.DatabaseCluster;
import software.amazon.awscdk.services.rds.DatabaseClusterEngine;
import software.amazon.awscdk.services.rds.InstanceProps;
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define a new VPC
Vpc vpc = Vpc.Builder.create(this, "MyVpc")
.maxAzs(3) // Maximum number of availability zones to use
.build();
// Define an RDS database cluster
DatabaseCluster dbCluster = DatabaseCluster.Builder.create(this, "MyRDSCluster")
.engine(DatabaseClusterEngine.AURORA)
.instanceProps(InstanceProps.builder()
.vpc(vpc)
.build())
.build();
// Get the port token (this is a token encoded as a number)
Number portToken = dbCluster.getClusterEndpoint().getPort();
// Print the value for our token at synthesis
System.out.println("portToken: " + portToken);
}
}
```
```
using Amazon.CDK;
using Constructs;
using Amazon.CDK.AWS.EC2;
using Amazon.CDK.AWS.RDS;
using System;
using System.Collections.Generic;
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define a new VPC
var vpc = new Vpc(this, "MyVpc", new VpcProps
{
MaxAzs = 3 // Maximum number of availability zones to use
});
// Define an RDS database cluster
var dbCluster = new DatabaseCluster(this, "MyRDSCluster", new DatabaseClusterProps
{
Engine = DatabaseClusterEngine.AURORA, // Remove parentheses
InstanceProps = new Amazon.CDK.AWS.RDS.InstanceProps // Specify RDS InstanceProps
{
Vpc = vpc
}
});
// Get the port token (this is a token encoded as a number)
var portToken = dbCluster.ClusterEndpoint.Port;
// Print the value for our token at synthesis
System.Console.WriteLine($"portToken: {portToken}");
}
}
}
```
```
package main
import (
"fmt"
"github.com/aws/aws-cdk-go/awscdk/v2"
"github.com/aws/aws-cdk-go/awscdk/v2/awsec2"
"github.com/aws/aws-cdk-go/awscdk/v2/awsrds"
"github.com/aws/constructs-go/constructs/v10"
"github.com/aws/jsii-runtime-go"
)
type CdkDemoAppStackProps struct {
awscdk.StackProps
}
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define a new VPC
vpc := awsec2.NewVpc(stack, jsii.String("MyVpc"), &awsec2.VpcProps{
MaxAzs: jsii.Number(3), // Maximum number of availability zones to use
})
// Define an RDS database cluster
dbCluster := awsrds.NewDatabaseCluster(stack, jsii.String("MyRDSCluster"), &awsrds.DatabaseClusterProps{
Engine: awsrds.DatabaseClusterEngine_AURORA(),
InstanceProps: &awsrds.InstanceProps{
Vpc: vpc,
},
})
// Get the port token (this is a token encoded as a number)
portToken := dbCluster.ClusterEndpoint().Port()
// Print the value for our token at synthesis
fmt.Println("portToken: ", portToken)
return stack
}
// ...
```
Lorsque nous exécutons`cdk synth`, la valeur de `portToken` est affichée sous forme de jeton codé par un numéro :
```
$ cdk synth --quiet
portToken: -1.8881545897087968e+289
```
### Passez des jetons codés
Lorsque vous transmettez des jetons codés par des nombres à d'autres constructions, il peut être judicieux de les convertir d'abord en chaînes. Par exemple, si vous souhaitez utiliser la valeur d'une chaîne codée par un nombre dans le cadre d'une chaîne concaténée, sa conversion améliore la lisibilité.
Dans l'exemple suivant, `portToken` il s'agit d'un jeton codé par un nombre que nous voulons transmettre à notre fonction Lambda dans le cadre de : `connectionString`
**Example**
```
import { Stack, Duration, CfnOutput, StackProps } from 'aws-cdk-lib';
// ...
import * as lambda from 'aws-cdk-lib/aws-lambda';
export class CdkDemoAppStack extends Stack {
constructor(scope: Construct, id: string, props?: StackProps) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// ...
// Example connection string with the port token as a number
const connectionString = `jdbc:mysql://mydb.cluster.amazonaws.com:${portToken}/mydatabase`;
// Use the connection string as an environment variable in a Lambda function
const myFunction = new lambda.Function(this, 'MyLambdaFunction', {
runtime: lambda.Runtime.NODEJS_20_X,
handler: 'index.handler',
code: lambda.Code.fromInline(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`),
environment: {
DATABASE_CONNECTION_STRING: connectionString, // Using the port token as part of the string
},
});
// Output the value of our connection string at synthesis
console.log("connectionString: " + connectionString);
// Output the connection string
new CfnOutput(this, 'ConnectionString', {
value: connectionString,
});
}
}
```
```
const { Stack, Duration, CfnOutput } = require('aws-cdk-lib');
// ...
const lambda = require('aws-cdk-lib/aws-lambda');
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// ...
// Example connection string with the port token as a number
const connectionString = `jdbc:mysql://mydb.cluster.amazonaws.com:${portToken}/mydatabase`;
// Use the connection string as an environment variable in a Lambda function
const myFunction = new lambda.Function(this, 'MyLambdaFunction', {
runtime: lambda.Runtime.NODEJS_20_X,
handler: 'index.handler',
code: lambda.Code.fromInline(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`),
environment: {
DATABASE_CONNECTION_STRING: connectionString, // Using the port token as part of the string
},
});
// Output the value of our connection string at synthesis
console.log("connectionString: " + connectionString);
// Output the connection string
new CfnOutput(this, 'ConnectionString', {
value: connectionString,
});
}
}
module.exports = { CdkDemoAppStack }
```
```
from aws_cdk import (
Duration,
Stack,
CfnOutput,
)
from aws_cdk import aws_lambda as _lambda
# ...
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define a new VPC
# ...
# Define an RDS database cluster
# ...
# Get the port token (this is a token encoded as a number)
port_token = db_cluster.cluster_endpoint.port
# ...
# Example connection string with the port token as a number
connection_string = f"jdbc:mysql://mydb.cluster.amazonaws.com:{port_token}/mydatabase"
# Use the connection string as an environment variable in a Lambda function
my_function = _lambda.Function(self, 'MyLambdaFunction',
runtime=_lambda.Runtime.NODEJS_20_X,
handler='index.handler',
code=_lambda.Code.from_inline("""
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
"""),
environment={
'DATABASE_CONNECTION_STRING': connection_string # Using the port token as part of the string
}
)
# Output the value of our connection string at synthesis
print(f"connectionString: {connection_string}")
# Output the connection string
CfnOutput(self, 'ConnectionString',
value=connection_string
)
```
```
// ...
import software.amazon.awscdk.CfnOutput;
import software.amazon.awscdk.services.lambda.Function;
import software.amazon.awscdk.services.lambda.Runtime;
import software.amazon.awscdk.services.lambda.Code;
import java.util.Map;
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
Number portToken = dbCluster.getClusterEndpoint().getPort();
// ...
// Example connection string with the port token as a number
String connectionString = "jdbc:mysql://mydb.cluster.amazonaws.com:" + portToken + "/mydatabase";
// Use the connection string as an environment variable in a Lambda function
Function myFunction = Function.Builder.create(this, "MyLambdaFunction")
.runtime(Runtime.NODEJS_20_X)
.handler("index.handler")
.code(Code.fromInline(
"exports.handler = async function(event) {\n" +
" return {\n" +
" statusCode: 200,\n" +
" body: JSON.stringify('Hello World!'),\n" +
" };\n" +
"};"))
.environment(Map.of(
"DATABASE_CONNECTION_STRING", connectionString // Using the port token as part of the string
))
.build();
// Output the value of our connection string at synthesis
System.out.println("connectionString: " + connectionString);
// Output the connection string
CfnOutput.Builder.create(this, "ConnectionString")
.value(connectionString)
.build();
}
}
```
```
// ...
using Amazon.CDK.AWS.Lambda;
using Amazon.CDK.AWS.RDS;
using Amazon.CDK;
using Constructs;
using System;
using System.Collections.Generic;
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define a new VPC
// ...
// Define an RDS database cluster
var dbCluster = new DatabaseCluster(this, "MyRDSCluster", new DatabaseClusterProps
{
// ... properties would go here
});
// Get the port token (this is a token encoded as a number)
var portToken = dbCluster.ClusterEndpoint.Port;
// ...
// Example connection string with the port token as a number
var connectionString = $"jdbc:mysql://mydb.cluster.amazonaws.com:{portToken}/mydatabase";
// Use the connection string as an environment variable in a Lambda function
var myFunction = new Function(this, "MyLambdaFunction", new FunctionProps
{
Runtime = Runtime.NODEJS_20_X,
Handler = "index.handler",
Code = Code.FromInline(@"
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
"),
Environment = new Dictionary
{
{ "DATABASE_CONNECTION_STRING", connectionString } // Using the port token as part of the string
}
});
// Output the value of our connection string at synthesis
Console.WriteLine($"connectionString: {connectionString}");
// Output the connection string
new CfnOutput(this, "ConnectionString", new CfnOutputProps
{
Value = connectionString
});
}
}
}
```
```
// ...
"github.com/aws/aws-cdk-go/awscdk/v2/awslambda"
)
type CdkDemoAppStackProps struct {
awscdk.StackProps
}
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
portToken := dbCluster.ClusterEndpoint().Port()
// ...
// Example connection string with the port token as a number
connectionString := fmt.Sprintf("jdbc:mysql://mydb.cluster.amazonaws.com:%s/mydatabase", portToken)
// Use the connection string as an environment variable in a Lambda function
myFunction := awslambda.NewFunction(stack, jsii.String("MyLambdaFunction"), &awslambda.FunctionProps{
Runtime: awslambda.Runtime_NODEJS_20_X(),
Handler: jsii.String("index.handler"),
Code: awslambda.Code_FromInline(jsii.String(`
exports.handler = async function(event) {
return {
statusCode: 200,
body: JSON.stringify('Hello World!'),
};
};
`)),
Environment: &map[string]*string{
"DATABASE_CONNECTION_STRING": jsii.String(connectionString), // Using the port token as part of the string
},
})
// Output the value of our connection string at synthesis
fmt.Println("connectionString: ", connectionString)
// Output the connection string
awscdk.NewCfnOutput(stack, jsii.String("ConnectionString"), &awscdk.CfnOutputProps{
Value: jsii.String(connectionString),
})
return stack
}
// ...
```
Si nous transmettons cette valeur à`connectionString`, la valeur de sortie lors de l'exécution `cdk synth` peut prêter à confusion en raison de la chaîne codée par des nombres :
```
$ cdk synth --quiet
connectionString: jdbc:mysql://mydb.cluster.amazonaws.com:-1.888154589708796e+289/mydatabase
```
Pour convertir un jeton codé par un nombre en chaîne, utilisez. [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Tokenization.html#static-stringifywbrnumberx](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Tokenization.html#static-stringifywbrnumberx) Dans l'exemple suivant, nous convertissons le jeton codé par un nombre en chaîne avant de définir notre chaîne de connexion :
**Example**
```
import { Stack, Duration, Tokenization, CfnOutput, StackProps } from 'aws-cdk-lib';
// ...
export class CdkDemoAppStack extends Stack {
constructor(scope: Construct, id: string, props?: StackProps) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// ...
// Convert the encoded number to an encoded string for use in the connection string
const portAsString = Tokenization.stringifyNumber(portToken);
// Example connection string with the port token as a string
const connectionString = `jdbc:mysql://mydb.cluster.amazonaws.com:${portAsString}/mydatabase`;
// Use the connection string as an environment variable in a Lambda function
const myFunction = new lambda.Function(this, 'MyLambdaFunction', {
// ...
environment: {
DATABASE_CONNECTION_STRING: connectionString, // Using the port token as part of the string
},
});
// Output the value of our connection string at synthesis
console.log("connectionString: " + connectionString);
// Output the connection string
new CfnOutput(this, 'ConnectionString', {
value: connectionString,
});
}
}
```
```
const { Stack, Duration, Tokenization, CfnOutput } = require('aws-cdk-lib');
// ...
class CdkDemoAppStack extends Stack {
constructor(scope, id, props) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
const portToken = dbCluster.clusterEndpoint.port;
// ...
// Convert the encoded number to an encoded string for use in the connection string
const portAsString = Tokenization.stringifyNumber(portToken);
// Example connection string with the port token as a string
const connectionString = `jdbc:mysql://mydb.cluster.amazonaws.com:${portAsString}/mydatabase`;
// Use the connection string as an environment variable in a Lambda function
const myFunction = new lambda.Function(this, 'MyLambdaFunction', {
// ...
environment: {
DATABASE_CONNECTION_STRING: connectionString, // Using the port token as part of the string
},
});
// Output the value of our connection string at synthesis
console.log("connectionString: " + connectionString);
// Output the connection string
new CfnOutput(this, 'ConnectionString', {
value: connectionString,
});
}
}
module.exports = { CdkDemoAppStack }
```
```
from aws_cdk import (
Duration,
Stack,
Tokenization,
CfnOutput,
)
# ...
class CdkDemoAppStack(Stack):
def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
super().__init__(scope, construct_id, **kwargs)
# Define a new VPC
# ...
# Define an RDS database cluster
# ...
# Get the port token (this is a token encoded as a number)
port_token = db_cluster.cluster_endpoint.port
# Convert the encoded number to an encoded string for use in the connection string
port_as_string = Tokenization.stringify_number(port_token)
# Example connection string with the port token as a string
connection_string = f"jdbc:mysql://mydb.cluster.amazonaws.com:{port_as_string}/mydatabase"
# Use the connection string as an environment variable in a Lambda function
my_function = _lambda.Function(self, 'MyLambdaFunction',
# ...
environment={
'DATABASE_CONNECTION_STRING': connection_string # Using the port token as part of the string
}
)
# Output the value of our connection string at synthesis
print(f"connectionString: {connection_string}")
# Output the connection string
CfnOutput(self, 'ConnectionString',
value=connection_string
)
```
```
// ...
import software.amazon.awscdk.Tokenization;
public class CdkDemoAppStack extends Stack {
public CdkDemoAppStack(final Construct scope, final String id) {
this(scope, id, null);
}
public CdkDemoAppStack(final Construct scope, final String id, final StackProps props) {
super(scope, id, props);
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
Number portToken = dbCluster.getClusterEndpoint().getPort();
// ...
// Convert the encoded number to an encoded string for use in the connection string
String portAsString = Tokenization.stringifyNumber(portToken);
// Example connection string with the port token as a string
String connectionString = "jdbc:mysql://mydb.cluster.amazonaws.com:" + portAsString + "/mydatabase";
// Use the connection string as an environment variable in a Lambda function
Function myFunction = Function.Builder.create(this, "MyLambdaFunction")
// ...
.environment(Map.of(
"DATABASE_CONNECTION_STRING", connectionString // Using the port token as part of the string
))
.build();
// Output the value of our connection string at synthesis
System.out.println("connectionString: " + connectionString);
// Output the connection string
CfnOutput.Builder.create(this, "ConnectionString")
.value(connectionString)
.build();
}
}
```
```
// ...
namespace CdkDemoApp
{
public class CdkDemoAppStack : Stack
{
internal CdkDemoAppStack(Construct scope, string id, IStackProps props = null) : base(scope, id, props)
{
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
var portToken = dbCluster.ClusterEndpoint.Port;
// ...
// Convert the encoded number to an encoded string for use in the connection string
var portAsString = Tokenization.StringifyNumber(portToken);
// Example connection string with the port token as a string
var connectionString = $"jdbc:mysql://mydb.cluster.amazonaws.com:{portAsString}/mydatabase";
// Use the connection string as an environment variable in a Lambda function
var myFunction = new Function(this, "MyLambdaFunction", new FunctionProps
{
// ...
Environment = new Dictionary
{
{ "DATABASE_CONNECTION_STRING", connectionString } // Using the port token as part of the string
}
});
// Output the value of our connection string at synthesis
Console.WriteLine($"connectionString: {connectionString}");
// Output the connection string
new CfnOutput(this, "ConnectionString", new CfnOutputProps
{
Value = connectionString
});
}
}
}
```
```
// ...
func NewCdkDemoAppStack(scope constructs.Construct, id string, props *CdkDemoAppStackProps) awscdk.Stack {
var sprops awscdk.StackProps
if props != nil {
sprops = props.StackProps
}
stack := awscdk.NewStack(scope, &id, &sprops)
// Define a new VPC
// ...
// Define an RDS database cluster
// ...
// Get the port token (this is a token encoded as a number)
portToken := dbCluster.ClusterEndpoint().Port()
// ...
// Convert the encoded number to an encoded string for use in the connection string
portAsString := awscdk.Tokenization_StringifyNumber(portToken)
// Example connection string with the port token as a string
connectionString := fmt.Sprintf("jdbc:mysql://mydb.cluster.amazonaws.com:%s/mydatabase", portAsString)
// Use the connection string as an environment variable in a Lambda function
myFunction := awslambda.NewFunction(stack, jsii.String("MyLambdaFunction"), &awslambda.FunctionProps{
// ...
Environment: &map[string]*string{
"DATABASE_CONNECTION_STRING": jsii.String(connectionString), // Using the port token as part of the string
},
})
// Output the value of our connection string at synthesis
fmt.Println("connectionString: ", connectionString)
// Output the connection string
awscdk.NewCfnOutput(stack, jsii.String("ConnectionString"), &awscdk.CfnOutputProps{
Value: jsii.String(connectionString),
})
fmt.Println(myFunction)
return stack
}
// ...
```
Lorsque nous exécutons`cdk synth`, la valeur de notre chaîne de connexion est représentée dans un format de plus en plus clair :
```
$ cdk synth --quiet
connectionString: jdbc:mysql://mydb.cluster.amazonaws.com:${Token[TOKEN.242]}/mydatabase
```
## Valeurs paresseuses
En plus de représenter les valeurs de temps de déploiement, telles que les AWS CloudFormation [paramètres, les](parameters.md) jetons sont également couramment utilisés pour représenter les valeurs latentes au moment de la synthèse. Il s'agit de valeurs pour lesquelles la valeur finale sera déterminée avant la fin de la synthèse, mais pas au moment où la valeur est construite. Utilisez des jetons pour transmettre une chaîne littérale ou une valeur numérique à une autre construction, tandis que la valeur réelle au moment de la synthèse peut dépendre d'un calcul qui n'a pas encore été effectué.
Vous pouvez créer des jetons représentant des valeurs paresseuses au moment de la synthèse en utilisant des méthodes statiques sur la `Lazy` classe, telles que [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Lazy.html#static-stringproducer-options](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Lazy.html#static-stringproducer-options)et. [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Lazy.html#static-numberproducer](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Lazy.html#static-numberproducer) Ces méthodes acceptent un objet dont la `produce` propriété est une fonction qui accepte un argument de contexte et renvoie la valeur finale lorsqu'elle est appelée.
L'exemple suivant crée un groupe Auto Scaling dont la capacité est déterminée après sa création.
**Example**
```
let actualValue: number;
new AutoScalingGroup(this, 'Group', {
desiredCapacity: Lazy.numberValue({
produce(context) {
return actualValue;
}
})
});
// At some later point
actualValue = 10;
```
```
let actualValue;
new AutoScalingGroup(this, 'Group', {
desiredCapacity: Lazy.numberValue({
produce(context) {
return (actualValue);
}
})
});
// At some later point
actualValue = 10;
```
```
class Producer:
def __init__(self, func):
self.produce = func
actual_value = None
AutoScalingGroup(self, "Group",
desired_capacity=Lazy.number_value(Producer(lambda context: actual_value))
)
# At some later point
actual_value = 10
```
```
double actualValue = 0;
class ProduceActualValue implements INumberProducer {
@Override
public Number produce(IResolveContext context) {
return actualValue;
}
}
AutoScalingGroup.Builder.create(this, "Group")
.desiredCapacity(Lazy.numberValue(new ProduceActualValue())).build();
// At some later point
actualValue = 10;
```
```
public class NumberProducer : INumberProducer
{
Func function;
public NumberProducer(Func function)
{
this.function = function;
}
public Double Produce(IResolveContext context)
{
return function();
}
}
double actualValue = 0;
new AutoScalingGroup(this, "Group", new AutoScalingGroupProps
{
DesiredCapacity = Lazy.NumberValue(new NumberProducer(() => actualValue))
});
// At some later point
actualValue = 10;
```
## Conversion au format JSON
Parfois, vous souhaitez produire une chaîne JSON de données arbitraires, sans savoir si les données contiennent des jetons. Pour encoder correctement en JSON toute structure de données, qu'elle contienne ou non des jetons, utilisez la méthode [https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Stack.html#towbrjsonwbrstringobj-space](https://docs.aws.amazon.com/cdk/api/v2/docs/aws-cdk-lib.Stack.html#towbrjsonwbrstringobj-space), comme indiqué dans l'exemple suivant.
**Example**
```
const stack = Stack.of(this);
const str = stack.toJsonString({
value: bucket.bucketName
});
```
```
const stack = Stack.of(this);
const str = stack.toJsonString({
value: bucket.bucketName
});
```
```
stack = Stack.of(self)
string = stack.to_json_string(dict(value=bucket.bucket_name))
```
```
Stack stack = Stack.of(this);
String stringVal = stack.toJsonString(java.util.Map.of( // Map.of requires Java 9+
put("value", bucket.getBucketName())));
```
```
var stack = Stack.Of(this);
var stringVal = stack.ToJsonString(new Dictionary
{
["value"] = bucket.BucketName
});
```