Dynamic block with variable number of attributes

[Mark Jaffe]

Hi,

We're up to Terraform 0.12.30 on the way to 0.13.x, and need to make this module definition for AWS elb resource. Currently, we have:

  dynamic "listener" {

    for_each = var.listeners

    content {

      instance_port      = listener.value.instance_port

      instance_protocol  = listener.value.instance_protocol

      lb_port            = listener.value.lb_port

      lb_protocol        = listener.value.lb_protocol

    }

  }

But if our listener has SSL cert, we need to use:

  dynamic "listener" {

    for_each = var.listeners

    content {

      instance_port      = listener.value.instance_port

      instance_protocol  = listener.value.instance_protocol

      lb_port            = listener.value.lb_port

      lb_protocol        = listener.value.lb_protocol

      ssl_certificate_id = listener.value.ssl_certificate_id

    }

  }

Which, of course will not work if there is no ssl_certificate_id in the non-ssl case. What would be the appropriate syntax for a conditional in the content block?

[Mark Jaffe]

Problem solved:

  dynamic "listener" {

    for_each = var.listeners

    content {

      instance_port      = listener.value.instance_port

      instance_protocol  = listener.value.instance_protocol

      lb_port            = listener.value.lb_port

      lb_protocol        = listener.value.lb_protocol

      ssl_certificate_id = try(listener.value.ssl_certificate_id, null)

    }

  }