wrong variable description and example

[Krad-dono]

So I used this module to provision database alarms as per example. It did not work - all alarms were stuck in Insufficient data state. I did raise a case to AWS support so they looked at my alarms and identified that database ID was used where Identifier need to be used. This is for RDS SQL Server at least.
Your example says:
db_instance_id = aws_db_instance.default.id
Should be:
db_instance_id = aws_db_instance.default.identifier
Please amend documentation accordingly.

[dudeitssm]

To add some more context, and to help out newbie Terraform users puzzled by this issue, here's what that means...

Example: I have a single node RDS cluster, example-rds with a writer node.
The correct value that has to be substituted within the db_instance_id = input would be db_instance_id = example-db-1 and not example-db.

I've also attached a screenshot to show what that means.

The green checkmark is the value you want substituted.
The red cross is what's currently happening in the repo provided example.