runner_sg_id should return the correct SG ID for docker-autoscaler

[jonmcewen]

Describe the bug

The output runner_sg_id returns the docker-machine worker SG ID or null. If runner_worker.type is set to "docker-autoscaler", the SG of the docker-autoscaler workers should be returned instead.

[jonmcewen]

@kayman-mk hello. Is this an easy fix while you are refactoring in preparation for the removal of docker-machine?

[jonmcewen]

For our use we could eventually switch to using runner_worker_egress_rules (a197e4f), but the output should still be fixed. Maybe something like this:

output "runner_sg_id" {
  description = "ID of the security group attached to the runner workers."
  value       = var.runner_worker.type == "docker-autoscaler" ? aws_security_group.docker_autoscaler[0].id : length(aws_security_group.docker_machine) > 0 ? aws_security_group.docker_machine[0].id : null
}

[kayman-mk]

Yes, it's a bug.

[jonmcewen]

Yes, it's a bug.

Thanks for fixing @kayman-mk !