TargetDescription.id missing in Resolvable union type in elasticloadbalancingv2/targetgroup.pkl

[christiaan-bronkhorst]

Summary

In the aws@0.1.1 plugin package, TargetDescription.id in elasticloadbalancingv2/targetgroup.pkl is typed as String instead of (String|formae.Resolvable). This prevents using cross-resource references (e.g., EC2
instance IDs) as target group targets — a fundamental use case for load balancers.

Affected Version

• Plugin: aws@0.1.1 (package://hub.platform.engineering/plugins/aws/schema/pkl/aws/aws@0.1.1)
• formae: 0.82.1

How to Reproduce

1. Create a project with the aws plugin:

  mkdir /tmp/formae-bug-repro && cd /tmp/formae-bug-repro
  formae project init --include aws -y

2. Replace main.pkl with a minimal reproducer:

  amends "@formae/forma.pkl"

  import "@formae/formae.pkl"
  import "@aws/ec2/instance.pkl"
  import "@aws/elasticloadbalancingv2/targetgroup.pkl"
  import "@aws/aws.pkl"

  stacks {
    new formae.Stack {
      label = "repro-stack"
      description = "Bug reproducer"
      target = new aws.Target {
        label = "repro-target"
        region = "af-south-1"
        profile = "default"
      }
      resources {
        // An EC2 instance
        new instance.Instance {
          label = "my-instance"
          imageId = "ami-12345678"
          instanceType = "t3.small"
        }
        // A target group referencing the instance ID (a Resolvable)
        local myInstance = new instance.Instance {
          label = "my-instance"
        }
        new targetgroup.TargetGroup {
          label = "my-tg"
          port = 6443
          protocol = "TCP"
          targetType = "instance"
          targets {
            new targetgroup.TargetDescription {
              id = myInstance.res.instanceId   // <-- THIS FAILS: InstanceResolvable assigned to String
              port = 6443
            }
          }
        }
      }
    }
  }

3. Run:

  formae eval main.pkl

4. Observe the error:

  –– Pkl Error ––
  Expected value of type `String`, but got type `aws.ec2.instance#InstanceResolvable`.

  23 | id: String
           ^^^^^^
  at aws.elasticloadbalancingv2.targetgroup#TargetDescription.id

Expected Behaviour

TargetDescription.id should accept (String|formae.Resolvable), allowing cross-resource references. This is the standard pattern used throughout the entire plugin. For example:

Field	File	Type
Listener.loadBalancerArn	elasticloadbalancingv2/listener.pkl	String|formae.Resolvable
Action.targetGroupArn	elasticloadbalancingv2/listener.pkl	(String|formae.Resolvable)?
TargetGroup.vpcId	elasticloadbalancingv2/targetgroup.pkl	(String|formae.Resolvable)?
Volume.volumeId	ec2/instance.pkl	String|formae.Resolvable
Instance.subnetId	ec2/instance.pkl	(String|formae.Resolvable)?
Instance.securityGroupIds	ec2/instance.pkl	Listing<String|formae.Resolvable>?
TargetDescription.id	elasticloadbalancingv2/targetgroup.pkl	String ← should be (String|formae.Resolvable)