fix(lambda): disable aws-lambda:useCdkManagedLogGroup feature flag when not set (#34613)

### Issue #34612 Closes #34612 ### Reason for this change `USE_CDK_MANAGED_LAMBDA_LOGGROUP` makes CDK create a new log group. This is not backwards compatible with older CDK versions where the log group already exists. ### Description of changes Change the default flag value to false ### Describe any new or updated permissions being added None ### Description of how you validated changes Ran integ tests ### Checklist - [X] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md) ---- *By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: aemada-aws

packages/aws-cdk-lib/aws-lambda/test/function.test.ts

@@ -5036,6 +5036,25 @@ describe('tag propagation to logGroup on FF USE_CDK_MANAGED_LAMBDA_LOGGROUP enab
  });
 });
 
+describe('USE_CDK_MANAGED_LAMBDA_LOGGROUP defaults to false when not specified', () => {
+ it('does not create a managed log group when context flag is not specified', () => {
+ // GIVEN
+ const app = new cdk.App(); // No context provided
+ const stack = new cdk.Stack(app, 'Stack');
+
+ // WHEN
+ new lambda.Function(stack, 'Function', {
+ code: lambda.Code.fromInline('exports.handler = async () => {};'),
+ handler: 'index.handler',
+ runtime: lambda.Runtime.NODEJS_20_X,
+ });
+
+ // THEN
+ const template = Template.fromStack(stack);
+ template.resourceCountIs('AWS::Logs::LogGroup', 0); // No log group should be created
+ });
+});
+
 describe('Lambda Function log group behavior', () => {
  it('throws if both logRetention and logGroup are set', () => {
  const app = new cdk.App();

packages/aws-cdk-lib/cx-api/FEATURE_FLAGS.md

@@ -188,7 +188,8 @@ The following json shows the current recommended set of flags, as `cdk init` wou
  "@aws-cdk/aws-stepfunctions:useDistributedMapResultWriterV2": true,
  "@aws-cdk/s3-notifications:addS3TrustKeyPolicyForSnsSubscriptions": true,
  "@aws-cdk/aws-ec2:requirePrivateSubnetsForEgressOnlyInternetGateway": true,
- "@aws-cdk/aws-s3:publicAccessBlockedByDefault": true
+ "@aws-cdk/aws-s3:publicAccessBlockedByDefault": true,
+ "@aws-cdk/aws-lambda:useCdkManagedLogGroup": true
  }
 }
 ```
@@ -225,7 +226,6 @@ are migrating a v1 CDK project to v2, explicitly set any of these flags which do
 
 | Flag | Summary | Type | Since | v1 default | v2 default |
 | ----- | ----- | ----- | ----- | ----- | ----- |
-| [@aws-cdk/aws-lambda:useCdkManagedLogGroup](#aws-cdkaws-lambdausecdkmanagedloggroup) | When enabled, CDK creates and manages loggroup for the lambda function | new default | | `false` | `true` |
 | [@aws-cdk/core:newStyleStackSynthesis](#aws-cdkcorenewstylestacksynthesis) | Switch to new stack synthesis method which enables CI/CD | fix | 1.39.0 | `false` | `true` |
 | [@aws-cdk/core:stackRelativeExports](#aws-cdkcorestackrelativeexports) | Name exports based on the construct paths relative to the stack, rather than the global construct path | fix | 1.58.0 | `false` | `true` |
 | [@aws-cdk/aws-rds:lowercaseDbIdentifier](#aws-cdkaws-rdslowercasedbidentifier) | Force lowercasing of RDS Cluster names in CDK | fix | 1.97.0 | `false` | `true` |
@@ -485,7 +485,7 @@ Refer aws-lambda/README.md for more details on Customizing Log Group creation.
 | Since | Default | Recommended |
 | ----- | ----- | ----- |
 | (not in v1) | | |
-| V2_NEXT | `true` | `true` |
+| V2_NEXT | `false` | `true` |
 
 **Compatibility with old behavior:** Disable the feature flag to let lambda service create logGroup or specify logGroup or logRetention
 

packages/aws-cdk-lib/cx-api/lib/features.ts

@@ -1641,7 +1641,7 @@ export const FLAGS: Record<string, FlagInfo> = {
  Refer aws-lambda/README.md for more details on Customizing Log Group creation.
  `,
  introducedIn: { v2: 'V2_NEXT' },
- defaults: { v2: true },
+ defaults: { v2: false },
  recommendedValue: true,
  compatibilityWithOldBehaviorMd: 'Disable the feature flag to let lambda service create logGroup or specify logGroup or logRetention',
  },

packages/aws-cdk-lib/cx-api/test/features.test.ts

@@ -44,11 +44,12 @@ test('feature flag defaults may not be changed anymore', () => {
  [feats.USE_NEW_S3URI_PARAMETERS_FOR_BEDROCK_INVOKE_MODEL_TASK]: true,
  [feats.PIPELINE_REDUCE_STAGE_ROLE_TRUST_SCOPE]: true,
  [feats.PIPELINE_REDUCE_CROSS_ACCOUNT_ACTION_ROLE_TRUST_SCOPE]: true,
- [feats.USE_CDK_MANAGED_LAMBDA_LOGGROUP]: true,
- // Add new disabling feature flags below this line
  [feats.ASPECT_STABILIZATION]: true,
+ // Add new disabling feature flags below this line
  [feats.LOG_USER_POOL_CLIENT_SECRET_VALUE]: false,
  [feats.USE_RESOURCEID_FOR_VPCV2_MIGRATION]: false,
+ [feats.USE_CDK_MANAGED_LAMBDA_LOGGROUP]: false,
+
  });
 });
 

packages/aws-cdk-lib/recommended-feature-flags.json

@@ -73,5 +73,6 @@
  "@aws-cdk/aws-stepfunctions:useDistributedMapResultWriterV2": true,
  "@aws-cdk/s3-notifications:addS3TrustKeyPolicyForSnsSubscriptions": true,
  "@aws-cdk/aws-ec2:requirePrivateSubnetsForEgressOnlyInternetGateway": true,
- "@aws-cdk/aws-s3:publicAccessBlockedByDefault": true
+ "@aws-cdk/aws-s3:publicAccessBlockedByDefault": true,
+ "@aws-cdk/aws-lambda:useCdkManagedLogGroup": true
 }