Terraform Count Index

Question

Has anyone found a way to do something like this?

Assume I have 3 public subnets with 3 nat gateways deployed across them.

Note the added ${count.index} within the aws_nat_gateway subnet_id which throws an error

data "aws_availability_zones" "availability_zones" {}
data "aws_subnet" "public_subnets" {
  count = "${length(data.aws_availability_zones.availability_zones.names)}"
  tags {
    Name = "public-subnet-${count.index}"
  }
}

data "aws_nat_gateway" "natg" {
  count     = "${length(data.aws_availability_zones.availability_zones.names)}"
  subnet_id = "${data.aws_subnet.public_subnets.${count.index}.id}"

  tags {
    Name = "public-subnet-nat-${count.index}"
  }
}

Answer 1

You should use ${data.aws_subnet.public_subnets.*.id[count.index]} instead. This uses the splat operator to return the list of the iterated subnets and then indexes based on the current count index.