aws_db_parameter_group: set lifecycle.create_before_destroy = true

[flokli]

Description

This allows importing paramter groups, without failing with the following error message:

Error: Error deleting DB parameter group: InvalidDBParameterGroupState: One or more database instances are still members of this parameter group foo-postgres12-parameter-group, so the group cannot be deleted
status code: 400, request id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

Motivation and Context

I previously used db_cluster_parameter_group_name and db_parameter_group_name to point to some externally-created parameter group names.

While trying to update the engine_version, it failed with some incompatibilities, so I wanted to switch to having the terraform module create them.

I:

• removed db_cluster_parameter_group_name
• removed db_parameter_group_name
• added create_db_cluster_parameter_group = true
• added create_db_parameter_group = true
• added `db_cluster_parameter_group_family = "aurora-postgresql12"
• added db_parameter_group_family = "aurora-postgresql12"

I moved the pre-existing parameter groups into the module state:

tf state mv 'module.foo.aws_db_parameter_group.aurora_db_postgres12_parameter_group' 'module.foo.module.aurora.aws_db_parameter_group.this[0]'
tf state mv 'module.foo.aws_rds_cluster_parameter_group.aurora_cluster_postgres12_parameter_group' 'module.foo.module.aurora.aws_rds_cluster_parameter_group.this[0]'

Terraform tried to delete the parameter groups first, before creating the new ones:

Error: Error deleting DB parameter group: InvalidDBParameterGroupState: One or more database instances are still members of this parameter group foo-postgres12-parameter-group, so the group cannot be deleted
status code: 400, request id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

Setting lifecycle.before_destroy on the lifecycle.create_before_destroy = true on the aws_db_parameter_group seems to help. Terraform first creates the new DB parameter group, and then removes the old one.

This has also been suggested in hashicorp/terraform-provider-aws#6448 (comment).

Breaking Changes

N/A

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[flokli]

I gave up on this - apparently it's not really possible to do an engine upgrade from aurora-postgresql12 to aurora-postgresql13 at all.

I ended up replacing db_cluster_parameter_group_name and db_parameter_group_name arguments with the magic default.aurora-postgresql12 string, and then updated it to default.aurora-postgresql13 during the upgrade.

[github-actions]

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