Cannot access module attribute in another resource in Terraform AWS

Question

Terraform code:

module "alb" {
  source  = "terraform-aws-modules/alb/aws"
  version = "8.1.0"

  // ...

  target_groups = [
    {
       // ...
    }
    },
    {
      name                 = "lb-number-one"
      backend_port         = 80
      backend_protocol     = "HTTPS"
      target_type          = "ip"
    }
  ]

  https_listeners = [
    {
      port               = 443
      protocol           = "HTTPS"
      certificate_arn    = aws_acm_certificate.this[0].arn
      target_group_index = 0
    }
  ]

   // ...

    https_listener_rules = [
    {
      actions = [{
        // ...
      }]

      conditions = [{
        // ...
      }]
    },
  ]
}

resource "aws_lb_listener_rule" "https_listener_rules" {
  listener_arn = module.alb.https_listeners[0].arn
  priority     = 100

  action {
    type             = "forward"
    target_group_arn = module.alb.target_groups[1].arn
  }

  condition {
    host_header {
      // ...
    }
  }
}

For some reason, when I try to apply the code above, I get the error, that module.alb is an object:

╷
│ Error: Unsupported attribute
│ 
│   on alb.tf line 92, in resource "aws_lb_listener_rule" "https_listener_rules":
│   92:   listener_arn = module.alb.https_listeners[0].arn
│     ├────────────────
│     │ module.alb is a object
│ 
│ This object does not have an attribute named "https_listeners".
╵
╷
│ Error: Unsupported attribute
│ 
│   on alb.tf line 97, in resource "aws_lb_listener_rule" "https_listener_rules":
│   97:     target_group_arn = module.alb.target_groups[1].arn
│     ├────────────────
│     │ module.alb is a object
│ 
│ This object does not have an attribute named "target_groups".

But why is he not able to access this attributes? And why does the fact, that module.alb is an object avoid accessing the attribute?

score 0 · Accepted Answer · answered Mar 10 '23 at 17:27

Please take the time to look at the documentation for the module you are using. There is no output defined for that module named https_listeners or target_groups.

There is an output named https_listener_arns and another output named target_group_arns which are probably what you are looking for.

Cannot access module attribute in another resource in Terraform AWS

1 Answers1