I wonder how I can access the security group object which is created as an underlying resource of the awsx FargateService? I want to create a security group which can be attached to the DB that my fargateservice containers are connecting to.

sg_allowPostGresFromECS:
    type: aws:ec2:SecurityGroup
    properties:
      description: Pulumi managed. Allow Postgres inbound traffic from ECS.
      ingress:
        - description: Postgres from ECS.
          fromPort: 0
          toPort: 5432
          protocol: tcp
          securityGroups:
            - ${???????}
      egress:
        - fromPort: 0
          toPort: 0
          protocol: "-1"
          cidrBlocks:
            - 0.0.0.0/0