Cloud Executable API

This module is part of the AWS Cloud Development Kit project.

V2 Feature Flags

  • @aws-cdk/aws-s3:createDefaultLoggingPolicy

Enable this feature flag to create an S3 bucket policy by default in cases where an AWS service would automatically create the Policy if one does not exist.

For example, in order to send VPC flow logs to an S3 bucket, there is a specific Bucket Policy that needs to be attached to the bucket. If you create the bucket without a policy and then add the bucket as the flow log destination, the service will automatically create the bucket policy with the necessary permissions. If you were to then try and add your own bucket policy CloudFormation will throw and error indicating that a bucket policy already exists.

In cases where we know what the required policy is we can go ahead and create the policy so we can remain in control of it.

https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/AWS-logs-and-resource-policy.html#AWS-logs-infrastructure-S3

cdk.json

{
  "context": {
    "@aws-cdk/aws-s3:createDefaultLoggingPolicy": true
  }
}

  • @aws-cdk/aws-sns-subscriptions:restrictSqsDescryption

Enable this feature flag to restrict the decryption of a SQS queue, which is subscribed to a SNS topic, to only the topic which it is subscribed to and not the whole SNS service of an account.

Previously the decryption was only restricted to the SNS service principal. To make the SQS subscription more secure, it is a good practice to restrict the decryption further and only allow the connected SNS topic to decryption the subscribed queue.

cdk.json

{
  "context": {
    "@aws-cdk/aws-sns-subscriptions:restrictSqsDescryption": true
  }
}

  • @aws-cdk/aws-apigateway:disableCloudWatchRole

Enable this feature flag to change the default behavior for aws-apigateway.RestApi and aws-apigateway.SpecRestApi to not create a CloudWatch role and Account. There is only a single ApiGateway account per AWS environment which means that each time you create a RestApi in your account the ApiGateway account is overwritten. If at some point the newest RestApi is deleted, the ApiGateway Account and CloudWatch role will also be deleted, breaking any existing ApiGateways that were depending on them.

When this flag is enabled you should either create the ApiGateway account and CloudWatch role separately or only enable the cloudWatchRole on a single RestApi.

cdk.json

{
  "context": {
    "@aws-cdk/aws-apigateway:disableCloudWatchRole": true
  }
}

  • @aws-cdk/core:enablePartitionLiterals

Enable this feature flag to have Stack.partition return a literal string for a stack’s partition when the stack has a known region configured. If the region is undefined, or set to an unknown value, the Stack.partition will be the CloudFormation intrinsic value AWS::Partition. Without this feature flag, Stack.partition always returns the CloudFormation intrinsic value AWS::Partition.

This feature will often simplify ARN strings in CDK generated templates, for example:

 Principal:
   AWS:
     Fn::Join:
       - ""
       - - "arn:"
         - Ref: AWS::Partition
         - :iam::123456789876:root

becomes:

 Principal:
   AWS: "arn:aws:iam::123456789876:root"

  • @aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker

Enable this feature flag to avoid setting the “ECS” deployment controller when adding a circuit breaker to an ECS Service, as this will trigger a full replacement which fails to deploy when using set service names. This does not change any behaviour as the default deployment controller when it is not defined is ECS.

cdk.json

{
  "context": {
    "@aws-cdk/aws-ecs:disableExplicitDeploymentControllerForCircuitBreaker": true
  }
}

  • @aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy

Enable this feature flag to use S3 Bucket Policy for granting permission fo Server Access Logging rather than using the canned LogDeliveryWrite ACL. ACLs do not work when Object Ownership is enabled on the bucket.

This flag uses a Bucket Policy statement to allow Server Access Log delivery, following best practices for S3.

https://docs.aws.amazon.com/AmazonS3/latest/userguide/enable-server-access-logging.html

{
  "context": {
    "@aws-cdk/aws-s3:serverAccessLogsUseBucketPolicy": true
  }
}

  • @aws-cdk/aws-rds:databaseProxyUniqueResourceName

Enable this feature flag to use unique resource names for each DatabaseProxy.

Previously, the default behavior for DatabaseProxy was to use id of the constructor for dbProxyName. In this case, users couldn’t deploy DatabaseProxys that have the same id in the same region.

This is a feature flag as the old behavior was technically incorrect, but users may have come to depend on it.

{
  "context": {
    "@aws-cdk/aws-rds:databaseProxyUniqueResourceName": true
  }
}

  • @aws-cdk/aws-redshift:columnId

Enable this feature flag to allow the CDK to track changes in Redshift columns through their id attribute. This is a breaking change, as the name attribute was currently being used to track changes to Redshift columns.

Enabling this feature flag comes at a risk for existing Redshift columns, as the name attribute of a redshift column was currently being used. Therefore, to change a Redshift columns’ name will essentially create a new column and delete the old one. This will cause data loss. If you choose to enable this flag, ensure that upon intial deployment (the first deployment after setting this feature flag), the name attribute of every column is not changed. After the intial deployment, you can freely change the name attribute of a column.

cdk.json

{
  "context": {
    "@aws-cdk/aws-redshift:columnId": true
  }
}

  • @aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2

Enable this feature flag to use the AmazonEMRServicePolicy_v2 managed policies for the EMR service role.

This is a feature flag as the old behavior will be deprecated, but some resources may require manual intervention since they might not have the appropriate tags propagated automatically.

https://docs.aws.amazon.com/emr/latest/ManagementGuide/emr-managed-iam-policies.html

cdk.json

{
  "context": {
    "@aws-cdk/aws-stepfunctions-tasks:enableEmrServicePolicyV2": true
  }
}

  • @aws-cdk/core:includePrefixInUniqueNameGeneration

Enable this feature flag to include the stack’s prefixes to the name generation process.

Not doing so can cause the name of stack to exceed 128 characters:

  • The name generation ensures it doesn’t exceed 128 characters

  • Without this feature flag, the prefix is prepended to the generated name, which result can exceed 128 characters

This is a feature flag as it changes the name generated for stacks. Any CDK application deployed prior this fix will most likely be generated with a new name, causing the stack to be recreated with the new name, and then deleting the old one. For applications running on production environments this can be unmanageable.

cdk.json

{
  "context": {
    "@aws-cdk/core:includePrefixInUniqueNameGeneration": true
  }
}

  • @aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion

Enable this feature flag to automatically use the latest available NodeJS version in the aws-lambda-nodejse.Function construct.

This allows creation of new functions using a version that will automatically stay up to date without breaking bundling of existing functions that externalize packages included in their environemnt such as aws-sdk.

Functions defined previously will continue to function correctly as long as they pass an explicit runtime version, or do not exclude packages during bundling.

cdk.json

{
  "context": {
    "@aws-cdk/aws-lambda-nodejs:useLatestRuntimeVersion": true
  }
}

  • @aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource

Enable this feature flag to update the default branch for CodeCommit source actions to main.

Previously, the default branch for CodeCommit source actions was set to master. However, this convention is no longer supported, and repositories created after March 2021 now have main as their default branch.

cdk.json

{
  "context": {
    "@aws-cdk/aws-codepipeline-actions:useNewDefaultBranchForCodeCommitSource": true
  }
}

  • @aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction

Enable this feature flag to change the logical ID of the LambdaPermission for the LambdaAction to include an alarm ID.

Previously, only one alarm with the LambdaAction could be created per Lambda. This flag allows multiple alarms with the LambdaAction for the same Lambda to be created.

cdk.json

{
  "context": {
    "@aws-cdk/aws-cloudwatch-actions:changeLambdaPermissionLogicalIdForLambdaAction": true
  }
}

  • @aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse

Enables Pipeline to set the default value for crossAccountKeys to false.

When this feature flag is enabled, and the crossAccountKeys property is not provided in a Pipeline construct, the construct automatically defaults the value of this property to false.

cdk.json

{
  "context": {
    "@aws-cdk/aws-codepipeline:crossAccountKeysDefaultValueToFalse": true
  }
}

  • @aws-cdk/aws-codepipeline:defaultPipelineTypeToV2

Enables Pipeline to set the default pipeline type to V2.

When this feature flag is enabled, and the pipelineType property is not provided in a Pipeline construct, the construct automatically defaults the value of this property to PipelineType.V2.

cdk.json

{
  "context": {
    "@aws-cdk/aws-codepipeline:defaultPipelineTypeToV2": true
  }
}

  • @aws-cdk/aws-kms:reduceCrossAccountRegionPolicyScope

Reduce resource scope of the IAM Policy created from KMS key grant to granting key only.

When this feature flag is enabled and calling KMS key grant method, the created IAM policy will reduce the resource scope from ‘*’ to this specific granting KMS key.

cdk.json

{
  "context": {
    "@aws-cdk/aws-kms:reduceCrossAccountRegionPolicyScope": true
  }
}

  • @aws-cdk/aws-eks:nodegroupNameAttribute

When enabled, nodegroupName attribute of the provisioned EKS NodeGroup will not have the cluster name prefix.

When this feature flag is enabled, the nodegroupName attribute will be exactly the name of the nodegroup without any prefix.

cdk.json

{
  "context": {
    "@aws-cdk/aws-eks:nodegroupNameAttribute": true
  }
}

  • @aws-cdk/aws-ec2:ebsDefaultGp3Volume

When enabled, the default volume type of the EBS volume will be GP3.

When this featuer flag is enabled, the default volume type of the EBS volume will be EbsDeviceVolumeType.GENERAL_PURPOSE_SSD_GP3

cdk.json

{
  "context": {
    "@aws-cdk/aws-ec2:ebsDefaultGp3Volume": true
  }
}

  • @aws-cdk/aws-ecs:removeDefaultDeploymentAlarm

When enabled, remove default deployment alarm settings.

When this featuer flag is enabled, remove the default deployment alarm settings when creating a AWS ECS service.

cdk.json

{
  "context": {
    "@aws-cdk/aws-ec2:ebsDefaultGp3Volume": true
  }
}

  • @aws-cdk/aws-stepfunctions-tasks:ecsReduceRunTaskPermissions

When enabled, IAM Policy created to run tasks won’t include the task definition ARN, only the revision ARN.

When this feature flag is enabled, the IAM Policy created to run tasks won’t include the task definition ARN, only the revision ARN. The revision ARN is more specific than the task definition ARN. See https://docs.aws.amazon.com/step-functions/latest/dg/ecs-iam.html for more details.

cdk.json

{
  "context": {
    "@aws-cdk/aws-stepfunctions-tasks:ecsReduceRunTaskPermissions": true
  }
}

  • @aws-cdk/aws-stepfunctions-taks:useNewS3UriParametersForBedrockInvokeModelTask

When enabled, use new props for S3 URI under input and output fields in task definition of state machine for bedrock invoke model.

When this feature flag is enabled, use newly introduced props s3InputUri and s3OutputUri to populate S3 uri under input and output fields in state machine task definition for Bedrock invoke model.

cdk.json

{
  "context": {
    "@aws-cdk/aws-stepfunctions-tasks:useNewS3UriParametersForBedrockInvokeModelTask": true
  }
}

  • @aws-cdk/aws-ecs:reduceEc2FargateCloudWatchPermissions

Currently, we will automatically add a number of cloudwatch permissions to the task role when no cloudwatch log group is specified as logConfiguration and it will grant ‘Resources’: [’*’] to the task role.

When this feature flag is enabled, we will only grant the necessary permissions when users specify cloudwatch log group.

cdk.json

{
  "context": {
    "@aws-cdk/aws-ecs:reduceEc2FargateCloudWatchPermissions": true
  }
}

  • @aws-cdk/aws-ec2:ec2SumTImeoutEnabled

Currently is both initOptions.timeout and resourceSignalTimeout are both specified in the options for creating an EC2 Instance, only the value from ‘resourceSignalTimeout’ will be used.

When this feature flag is enabled, if both initOptions.timeout and resourceSignalTimeout are specified, the values will to be summed together.

cdk.json

{
  "context": {
    "@aws-cdk/aws-ec2:ec2SumTImeoutEnabled": true
  }
}

  • @aws-cdk/aws-appsync:appSyncGraphQLAPIScopeLambdaPermission

Currently, when using a Lambda authorizer with an AppSync GraphQL API, the AWS CDK automatically generates the necessary AWS::Lambda::Permission to allow the AppSync API to invoke the Lambda authorizer. This permission is overly permissive because it lacks a SourceArn, meaning it allows invocations from any source.

When this feature flag is enabled, the AWS::Lambda::Permission will be properly scoped with the SourceArn corresponding to the specific AppSync GraphQL API.

cdk.json

{
  "context": {
    "@aws-cdk/aws-ec2:appSyncGraphQLAPIScopeLambdaPermission": true
  }
}

  • @aws-cdk/aws-rds:setCorrectValueForDatabaseInstanceReadReplicaInstanceResourceId

When enabled, the value of property instanceResourceId in construct DatabaseInstanceReadReplica will be set to the correct value which is DbiResourceId instead of currently DbInstanceArn* (fix)

When this feature flag is enabled, the value of that property will be as expected set to DbiResourceId attribute, and that will fix the grantConnect method.

cdk.json

{
  "context": {
    "@aws-cdk/aws-rds:setCorrectValueForDatabaseInstanceReadReplicaInstanceResourceId": true
  }
}

  • @aws-cdk/aws-lambda-nodejs:sdkV3ExcludeSmithyPackages

Currently, when bundling Lambda functions with the non-latest runtime that supports AWS SDK JavaScript (v3), only the @aws-sdk/* packages are excluded by default. However, this can cause version mismatches between the @aws-sdk/* and @smithy/* packages, as they are tightly coupled dependencies in AWS SDK v3.

When this feature flag is enabled, both @aws-sdk/* and @smithy/* packages will be excluded during the bundling process. This ensures that no mismatches occur between these tightly coupled dependencies when using the AWS SDK v3 in Lambda functions.

cdk.json

{
  "context": {
    "@aws-cdk/aws-lambda-nodejs:sdkV3ExcludeSmithyPackages": true
  }
}

  • @aws-cdk/aws-dynamodb:resourcePolicyPerReplica

If this flag is not set, the default behavior for TableV2 is to use a different resourcePolicy for each replica.

If this flag is set to false, the behavior is that each replica shares the same resourcePolicy as the source table. This will prevent you from creating a new table which has an additional replica and a resource policy.

This is a feature flag as the old behavior was technically incorrect but users may have come to depend on it.

cdk.json

{
  "context": {
    "@aws-cdk/aws-dynamodb:resourcePolicyPerReplica": false,
  },
}