provider/aws: [question] DBName cannot be set when restoring from a MySQL, PostgreSQL, or MariaDB snapshot

[hashibot]

This issue was originally opened by @hgontijo as hashicorp/terraform#11278. It was migrated here as part of the provider split. The original body of the issue is below.

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AWS RDS does not allow setting the DBName when restoring from a MySQL, PostgreSQL, or MariaDB snapshot, however it allows when restoring for Oracle and SQL Server -- vide cli documentation. A recent change on Terraform sets the DB Name on a restore operation for all databases. The current Terraform behavior is to show an AWS RDS exception (see below) whenever DB Name is set in a restore operation.
For this use case, is expected from Terraform to behave exact like AWS API or to execute a proactive validation before submission? Is expected Terraform to execute any validation during plan operation?

Actual Terraform Behavior

DB name is set on a restore from snapshot and Terraform issues this error:

* aws_db_instance.db_master: Error creating DB Instance: InvalidParameterValue: DBName must be null when Restoring for this Engine.
	status code: 400, request id: 48a17d5b-dc0c-11e6-8a5c-39e234c22f55

Actual AWS CLI Behavior

$ aws rds restore-db-instance-from-db-snapshot \
   --db-subnet-group-name default-vpc \
    --db-instance-identifier foo \
    --db-snapshot-identifier db-snapshot
    --db-name name
An error occurred (InvalidParameterValue) when calling the RestoreDBInstanceFromDBSnapshot operation: DBName name cannot be used.  It is a reserved word for this engine

Terraform Version

0.8.4

Affected Resource(s)

• aws_db_instance

Steps to Reproduce

resource "aws_db_instance" "db_master" {
  ...
  name = "name"
  snapshot_identifier = "db-snapshot"
}

1. terraform apply

References

• fix(diffDynamoDbGSI): ignore ordering of non_key_attributes in equali… #9988
• **Terraform issues on the .12.12 version: need multiple plan/apply to create the eks infra on aws** #10664

[aviaviavi]

Is there a workaround for this? I'd like to restore my DB from a snapshot, but currently seem unable to do this from terraform.

[hgontijo]

@aviaviavi, the workaround is to not set the name while restoring a DB snapshot.

resource "aws_db_instance" "db_master" {
  ...
  name = ""
  snapshot_identifier = "db-snapshot"
}

You can also override the name parameter programmatically to avoid changing the Terraform script.

[aviaviavi]

Ok thanks @hgontijo.

I'll give this a try when I'm needing to do a restore next

[brandonstevens]

I'm not able to reproduce this issue and it appears to be fixed by this PR: hashicorp/terraform#13140.

[bflad]

Thanks @brandonstevens -- that does appear to be the case here. If there is still an issue on the latest version of the AWS provider, please open a new issue with all the relevant details and we'll troubleshoot further. 👍

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!