Log Retention for Aurora Serverless in CloudFormation - amazon-web-services

Question

I have a Aurora Cluster (Serverless - PostgreSQL) setup in CloudFormation and I want to configure the Log Retention to be around 7 days but I haven't been able to find where to set this setting.
This is my CloudFormation definition for the DBCluster:
AuroraDBCluster:
Type: AWS::RDS::DBCluster
DeletionPolicy: Delete
UpdateReplacePolicy: Delete
Properties:
Engine: aurora-postgresql
EngineMode: serverless
EngineVersion: 10.7
DatabaseName: test-db
DeletionProtection: false
ScalingConfiguration:
AutoPause: True
MaxCapacity: 8
MinCapacity: 2
SecondsUntilAutoPause: 300
VpcSecurityGroupIds:
- !Ref AuroraClusterSecurityGroup
Port: !Ref DBPort
MasterUsername:
!Join ['', ['{{resolve:secretsmanager:', !Ref AuroraMasterSecret, ':SecretString:username}}' ]]
MasterUserPassword:
!Join ['', ['{{resolve:secretsmanager:', !Ref AuroraMasterSecret, ':SecretString:password}}' ]]
DBSubnetGroupName: !Ref DBSubnetGroup
BackupRetentionPeriod: 35
DBClusterParameterGroupName: !Ref RDSDBClusterParameterGroup
StorageEncrypted: true
KmsKeyId: !Ref AuroraKMSCMK
I have created a different LogGroup like this:
AuroraClusterLogGroup:
Type: "AWS::Logs::LogGroup"
Properties:
RetentionInDays: 7
LogGroupName: !Join ["", ["/aws/rds/cluster/", !Ref AuroraDBCluster, /postgresql]]
But when I deploy the stack, it says:
CREATE_FAILED AWS::Logs::LogGroup AuroraClusterLogGroup /aws/rds/cluster/aurora-serverless-db-ufeihfhef74465/postgresql already exists
Because (I think) the AuroraDBCluster resource creates its own LogGroup with the same name.
I have reviewed the AWS::RDS::DBCluster documentation but I have not found any references for the Log Retention.
What can I do in this case?
Thanks!

Answer 1

If Aurora has already created its own log group, you can't change it from CloudFormation. The only way to do this would be use custom resource in your template.
In the custom resource you could use put-retention-policy to modify the retention time of chosen log group.