aws_ec2_transit_gateway_vpc_attachment creates diff on each plan

[bebold-jhr]

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Terraform CLI and Terraform AWS Provider Version

Terraform v1.1.7
registry.terraform.io/hashicorp/aws v4.19.0

Affected Resource(s)

• aws_ec2_transit_gateway_vpc_attachment

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

resource "aws_ec2_transit_gateway_vpc_attachment" "this" {
  subnet_ids                                      = values(aws_subnet.attachment).*.id
  transit_gateway_id                              = data.aws_ec2_transit_gateway.this.id
  vpc_id                                          = aws_vpc.this.id
  ipv6_support                                    = "disable"
  transit_gateway_default_route_table_association = false
  transit_gateway_default_route_table_propagation = false
}

terraform-provider-aws/examples/transit-gateway-cross-account-vpc-attachment for remaining resources.

Debug Output

Panic Output

Expected Behavior

No changes when executing plan after apply.

Actual Behavior

Tries to set default route properties from true to false on each subsequent plan.

aws_ec2_transit_gateway_vpc_attachment.this will be updated in-place
  ~ resource "aws_ec2_transit_gateway_vpc_attachment" "this" {
        id                                              = "tgw-attach-#########"
      ~ transit_gateway_default_route_table_association = true -> false
      ~ transit_gateway_default_route_table_propagation = true -> false
        # (8 unchanged attributes hidden)
    }

Steps to Reproduce

1. terraform apply
2. terraform plan

Important Factoids

References

• #0000

[ewbankkit]

@bebold-jhr Thanks for raising this issue.
It has already been noticed in #21438. I'm going to close this one as a duplicate so that we can concentrate discussion in the linked issue.
Please add any additional comments there.

[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.