AWS RDS Read Replica on a different VPC

Question

I am trying to create an rds mysql read replica in a different vpc in the same region. This doesn't seem to work. I am getting the below error.

I am able to create a cross region read replica, here obviously the vpcs are different. But it works there and not within the same region.

Any idea why this could be the case?

The DB instance and EC2 security group are in different VPCs. The DB instance is in vpc-b40d62d3 and the EC2 security group is in vpc-3f6cc45b (Service: AmazonRDS; Status Code: 400; Error Code: InvalidParameterCombination; Request ID: 56d7eb7c-8cd7-490a-b979-ef678f4f6ed7)

This was asked earlier and the answer was not supported and use a custom solution. Asking again as that was a 3 year old post and cloud moves fast. :)

Cheers.

Answer 1

Tried this a week ago in RDS console but didn't work. I got the same error. But It is supported. At least in aws-cli version 1.16.

aws rds create-db-instance-read-replica \
  --db-instance-identifier [yourmaindb] \
  --source-db-instance-identifier [arn resource url of the source] \
  --db-subnet-group-name [subnet in a different VPC] \
  --vpc-security-group-ids [security group in a different VPC]