feat: Ignore GSI changes

[pablotp]

what

• Ignore the changes made to the global-secondary-index.

why

• Changes made to the global_secondary_index.read|write_capacity by the autoscaler causes drift.

references

• No method to ignore changes in DynamoDB GSI hashicorp/terraform-provider-aws#671

[pablotp]

/terratest

[RoseSecurity]

Until the provider addresses this bug, this situation appears fair. We might need to add a README note to document that setting this option means Terraform will ignore any changes to GSIs and require manual or automated application.

[pablotp]

Until the provider addresses this bug, this situation appears fair. We might need to add a README note to document that setting this option means Terraform will ignore any changes to GSIs and require manual or automated application.

Sounds good 👍🏻
I've just pushed aa6c434
Please let me know whether or not it meets your expectations. I generated the README.d using make readme, and it added a couple of unrelated changes (mainly replacing <br> with <br/>).

[mergify]

💥 This pull request now has conflicts. Could you fix it @pablotp? 🙏

[RoseSecurity]

/terratest

I can't think of any alternative solutions to this issue, but I'd love to get a second set of eyes from the team on this change.

[pablotp]

I can't think of any alternative solutions to this issue, but I'd love to get a second set of eyes from the team on this change.

Right now, I can't either.
After using this solution for a bit, I must admit that it gets tricky when you need to make changes apart from read|write_capacity (e.g., new secondary indexes). Therefore, I feel like this issue needs a solution at the provider level hashicorp/terraform-provider-aws#671.