Error creating AWS MySQL RDS instance with Terraform - mysql

Question

When creating an Amazon AWS RDS MySQL 5.7 db instance using Terraform "terraform-aws-modules/rds/aws" module, I started getting a strange error after > 1 hour. In other contexts in the past the same script worked (even more involved versions creating cross-region read replica in 2 other regions (3 in total).
When I tried to deploy to a different VPC recently I started getting an error after spending ~1 hour on the db options group resource (so not even reaching db deploy).
The error message is:
aws_db_option_group.this: Error creating DB Option Group: InternalFailure: An internal error has occurred. Please try your query again at a later time.
status code: 500 root.rds-virginia.db.db_option_group: eval: *terraform.EvalSequence
How to resolve or work around this?

Answer 1

Creating a dummy db option group (even though we don't need it for this use case) seems to work around this issue:
resource "aws_db_option_group" "some-option-group" {
name = "dummy-mysql-option-group"
option_group_description = "Dummy Mysql option group"
engine_name = "mysql"
major_engine_version = "5.7"
}
Terraform db option group docs: https://www.terraform.io/docs/providers/aws/r/db_option_group.html