StateUpgradeFunc Can Receive nil State Map

[bflad]

SDK version

v1.9.0

Relevant provider source code

https://github.com/terraform-providers/terraform-provider-aws/blob/2cb4e3f7f017feb338e0ba2ffdf409d6b0c91793/aws/resource_aws_db_instance.go#L29-L36

https://github.com/terraform-providers/terraform-provider-aws/blob/2cb4e3f7f017feb338e0ba2ffdf409d6b0c91793/aws/resource_aws_db_instance_migrate.go#L381-L384

Terraform Configuration Files

Can try to provide if needed, but not sure how we got here either. 😄

Debug Output

https://gist.github.com/ca3825d27e669d6e42c4d3e40f9acaff

Expected Behavior

An error to be raised by the SDK about the situation, the SDK to skip the StateUpgradeFunc, or the State Migration documentation to mention the need for nil checking (and potentially why).

Actual Behavior

Provider panic due to lack of nil checking in StateUpgraderFunc.

Steps to Reproduce

• terraform init (Terraform AWS Provider version 2.48.0 or earlier, which will have aws_db_instance resource with SchemaVersion: 0)
• terraform apply
• ??? (not sure how it got into empty raw state)
• terraform init (Terraform AWS Provider version 2.49.0 or later)
• terraform plan

References

• panic when upgrading state schema of aws_db_instance terraform-provider-aws#12771

[bflad]

Easiest thing to do here will be to add a sentence to the StateUpgradeFunc documentation about nil checking.

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