[Bug]: Implicit import of aws_lb_listener instead of error "A listener already exists on this port for this load balancer"

[dga-nagra]

Terraform Core Version

1.6.6

AWS Provider Version

5.3.1

Affected Resource(s)

• aws_lb_listener

Expected Behavior

I expect the error

A listener already exists on this port for this load balancer ... To be raised

Actual Behavior

No error is raised and the ARN output is the same. Previously added rules are lost silently.

Relevant Error/Panic Output Snippet

No response

Terraform Configuration Files

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.31"
    }
  }
}

provider "aws" {
  # Configuration options
  region = "eu-west-1"
}

resource "aws_lb_listener" "https" {
  load_balancer_arn = data.aws_lb.test.arn
  port              = "443"
  protocol          = "HTTPS"
  ssl_policy        = "..."  # Any ssl policy
  certificate_arn   = "..."  # Any certificate arn
  default_action {
    type = "fixed-response"
    fixed_response {
      content_type = "text/plain"
      message_body = "Invalid request"
      status_code  = "200"
    }
  }
}

output "aws_lb_listener_created" {
  value = "Listener arn: ${aws_lb_listener.https.arn}"
}

Steps to Reproduce

I have the following same definition in 2 different terraform projects but working on the same AWS account.

I run one of the terraform project, then, once the first one is finished, I run the second one. The output is the same and no error was raised.

Debug Output

No response

Panic Output

No response

Important Factoids

No response

References

No response

Would you like to implement a fix?

None

[github-actions[bot]]

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[acwwat]

I suspect that this is an upstream bug. I am able to reproduce the problem using the AWS CLI. Running a similar command below multiple time would succeed instead of failing with a DuplicateListener error as described in the CreateListener API reference. I would recommend opening an AWS Support ticket and have AWS look at the server side of the API.

Note that I also tried reproducing the problem in AWS Management Console and it returns a "You may not have duplicate ports defined." warning for the port field on submit. Although that's probably just UI validation.

aws elbv2 create-listener --load-balancer-arn <alb-arn> --port 80 --protocol HTTP --default-actions Type=forward,TargetGroupArn=<http-target-group-arn>

[rafael-debug]

Hey, guys, I'm also having this same problem. A listener already exists on this port for this load balancer in CLI and console it works fine.

[adampoplawski]

I have same issues on 1.9.2. We were adding listeners this way already before.