[Docs]: conflicting behaviour for storage autoscaling for RDS

[Kurtyjlee]

Documentation Link

https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/db_instance

Description

max_allocated_storage - (Optional) When configured, the upper limit to which Amazon RDS can automatically scale the storage of the DB instance. Configuring this will automatically ignore differences to allocated_storage. Must be greater than or equal to allocated_storage or 0 to disable Storage Autoscaling.

To enable Storage Autoscaling with instances that support the feature, define the max_allocated_storage argument higher than the allocated_storage argument. Terraform will automatically hide differences with the allocated_storage argument value if autoscaling occurs.

In the docs, it says to max_allocated_storage ≥ allocated_storage || max_allocated_storage == 0 to disable storage autoscaling, however, in another part of the documentation, it says it will enable storage autoscaling. Is this discrepancy expected? if not, what should the actual behaviour be?

References

No response

Would you like to implement a fix?

Yes

[github-actions]

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[justinretzolk]

Hey @Kurtyjlee 👋 Thank you for taking the time to raise this! I had to re-read the documentation a couple of times (further proving your point that it should be more clear), however, this seems to be a matter of the last sentence of the max_allocated_storage argument's documentation being a bit clumsy. There are three possibilities with regards to the argument:

1. Not defined: Does not enable autoscaling, necessary for DB instances that don't support autoscaling
2. Defined as greater than or equal to allocated_storage: Enable autoscaling for the DB instance
3. Defined as 0: Explicitly disable autoscaling for DB instances that support it

Would rewording that last sentence as follows make this more clear?

Must be greater than or equal to allocated_storage to enable Storage Autoscaling, or set to 0 to disable Storage Autoscaling for instances that support it.

[Kurtyjlee]

Hey @justinretzolk, thank you for clarifying! That rewording definitely makes it clearer. Would it be okay if I went ahead and submitted a PR to implement this change?

[justinretzolk]

I'm glad that made sense @Kurtyjlee! If you're up for raising a pull request for this, please feel free to! I try to keep up with documentation pull requests and get them merged as quick as I can, but feel free to tag me in and I'll get it reviewed.

[Kurtyjlee]

Hi @justinretzolk I have created the PR here, requesting your review!

[github-actions]

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[github-actions]

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