如何使用 Terraform 检索给定 VPC 中的 su.net？

Question

I was trying to retrieve the su.nets in a given VPC, in my case the default VPC, however I keep getting an error:

data "aws_vpc" "default_vpc" {
  default = true
}

data "aws_subnet" "subnets" {
  vpc_id = data.aws_vpc.default_vpc.id
}

output "subnets_out" {
  value = data.aws_subnet.subnets
}

Error: multiple EC2 Su.nets matched; use additional constraints to reduce matches to a single EC2 Su.net

The first data call works, I get my default VPC id, however the second one fails.

Originally I had 1 su.net in my default VPC and at that time, the second data call worked too but to my surprise it returned the su.net as a map instead of a map within a set. So I was curious what would happen if there was more than one su.nets in my VPC but then the data call failed.

What I find really confusing is that the Terraform documentation says:

This resource can be useful for getting back a set of su.net ID s .

If it's supposed to return a set of su.net IDs, then why is it an issue that multiple su.nets were matched?

Answer 1

aws_su.net is a resource for a specific su.net. Its not for a collection of su.nets. so when you pass the VPC_ID, aws is finding more than one su.net in that VPC. Its not possible to store more than one su.nets in aws_su.net

https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/su.net

aws_su.net provides details about a specific VPC su.net.

It sounds like you should be using aws_su.nets https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/su.nets

This resource can be useful for getting back a set of su.net IDs.

This will return you a list of su.net ID's which you can then use in a foreach in aws_su.net to get the specific details of each su.net