[Bug]: incorrect duplicate route detection

[rus-geek]

Terraform Core Version

1.3.3

AWS Provider Version

5.41.0

Affected Resource(s)

aws_route

Expected Behavior

Given a route table containing a propagated route to 0.0.0.0/0, I should be able to create a static route to 0.0.0.0/0 to override the propagated route.

Actual Behavior

terraform refuses to create the route, incorrectly indicating that it is a duplicate

Relevant Error/Panic Output Snippet

Error: RouteAlreadyExists: Route in Route Table (rtb-xxx) with destination (0.0.0.0/0) already exists

Terraform Configuration Files

resource "aws_route" "default_route" {
  route_table_id         = <your route table here>
  destination_cidr_block = "0.0.0.0/0"
  transit_gateway_id     = <your TGW here>
}

Steps to Reproduce

Create a VPC with a propagated route to 0.0.0.0/0 with any next hop.
Attempt to add a static route to 0.0.0.0/0 with any next hop.

Debug Output

No response

Panic Output

Error: RouteAlreadyExists: Route in Route Table (rtb-xxx) with destination (0.0.0.0/0) already exists

Important Factoids

No response

References

from the AWS documentation: "If the destination of a propagated route is identical to the destination of a static route, the static route takes priority..."

https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Route_Tables.html#route-tables-priority

Would you like to implement a fix?

None

[github-actions]

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[justinretzolk]

Hey @rus-geek 👋 Thank you for taking the time to raise this! I can't quite tell from the log snippet provided, but this error looks to be coming from the AWS API itself. Are you able to provide debug logging (redacted as needed) and/or test from the AWS CLI to see if it behaves the same? That's often a decent indicator in situations like this.

[rus-geek]

This works with prior versions of the provider, so it's allowed by AWS. The bug appears to have been introduced in this PR which "fixed" the creation of duplicate resources. #36326

We are able to create this route directly with AWS, and I am also able to create the route using 5.35.0 instead of 5.41.0

[rus-geek]

The error message is being produced here: https://github.com/hashicorp/terraform-provider-aws/pull/36326/files#diff-75640a85d46fcb8ff09efe164520cac42e5e8ccb3c8d641bb96ef678ca472388R199

[ewbankkit]

@rus-geek Thanks for raising this issue 👏.
I can reproduce this for the very similar case of the VPC-local route added via CreateRouteTable.
The fix is to check that the duplicate route was created via CreateRoute and only fail then.
I can get this fixed for today's Terraform AWS Provider v5.42.0 release.

[github-actions]

Warning

This issue has been closed, meaning that any additional comments are hard for our team to see. Please assume that the maintainers will not see them.

Ongoing conversations amongst community members are welcome, however, the issue will be locked after 30 days. Moving conversations to another venue, such as the AWS Provider forum, is recommended. If you have additional concerns, please open a new issue, referencing this one where needed.

[github-actions]

This functionality has been released in v5.42.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[rus-geek]

Confirmed that this works as expected in 5.42.0. We are again able to create static routes that 'override' propagated routes.

[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.