db_instance_id is returning the DB Resource ID

[jwoytek]

Description

I am using this module as part of a module in our project's infrastructure. I recently began adding some automated monitoring and was trying to set up some alarms for some RDS metrics. When I attempted to have the module output the db_instance_id, I instead get the db_resource_id returned.

The console indicates that an appropriate identifier is set, and requesting the arn for the rds instance shows the identifier correctly.

• ✋ I have searched the open/closed issues and my issue is not listed.

Versions

• Module version [Required]: 5.9.0

• Terraform version: 1.4.6

• Provider version(s): 5.1.0

Reproduction Code [Required]

output "db_instance_id" {
  value = module.db.db_instance_id
}

Steps to reproduce the behavior:

1. Deploy RDS using module
2. Request db_instance_id of the deployed database

Expected behavior

db_instance_id should return the instance identifier and not the resource identifier.

Actual behavior

db_instance_id returns the resource identifier.

Terminal Output Screenshot(s)

Example (partially redacted):

app_db_id = "db-63B5TPHO4P6G2NRAVXEEXXXXXX"
oauth_db_id = "db-IC6E5RWM5UD6OOYMFTKIXXXXXX"

Additional context

Note that another infrastructure deployment operating with provider version 4.58.0 and module version 5.6.0 returns the instance identifier correctly.

[jwoytek]

I may have found a thread to pull on here:

hashicorp/terraform-provider-aws#507

This ticket in the AWS provider is to allow users to change the DB identifier without destroying the existing resource. It seems there are some changes in a commit referenced there that have the module use the resource identifier instead of the instance identifier in some cases. I haven't parsed this fully yet, but this might be part of the issue.

[jwoytek]

OK, I believe I have found the issue.

dee-kryvenko/terraform-provider-aws@7eed983#diff-ca7f85b82bb2b9a4d5dcceea9a2f6a17fa978071f44c026f954e005598c61eecR1349

The id field of aws_db_instance is now returning the resource ID, due to the change in the previously referenced ticket.

This line:
dee-kryvenko/terraform-provider-aws@7eed983#diff-ca7f85b82bb2b9a4d5dcceea9a2f6a17fa978071f44c026f954e005598c61eecR1420

... appears to create a new and currently undocumented attribute named identifier that will return the actual instance identifier.

This was merged as hashicorp/terraform-provider-aws#31232.

I do not have the ability to test a fix at the moment, but it appears that in addition to the issue in this module, there is probably also a documentation update that needs to be made on the provider end (submitted here: hashicorp/terraform-provider-aws#31854).

[jwoytek]

Ugh I missed that this is the same as #495 (and handled by PR #496) because my search was apparently not awesome enough.

[antonbabenko]

This issue has been resolved in version 6.0.0 🎉

[cfernhout]

Thanks, this change had broken some stuff inexplicably when upgrading. Thanks for the report and fix! 🙏

[github-actions]

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 have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.