I am creating an AWS VPC with a single public subnet in a brand-new Terraform project, consisting only of a main.tf file. In that file, I am using two resource blocks, aws_vpc and aws_subnet. The second resource must be attached to the first using the vpc_id attribute. The value of this attribute is created only upon application, so it cannot be hard-coded. How do I get the ID of the resource I just created, so I can use it in the subsequent block?
resource "aws_vpc" "my_vpc" { cidr_block = "102.0.0.0/16" tags = { Name = "My-VPC" } } resource "aws_subnet" "my_subnet" { vpc_id = # what goes here? cidr_block = "102.0.0.0/24" tags = { Name = "My-Subnet" } }
The docs give the example of data.aws_subnet.selected.vpc_id for vpc_id. The value of this appears to depend on two other blocks, variable and data. I am having a hard time seeing how to wire these up to my VPC. I tried copying them directly from the docs. Upon running terraform plan I get the prompt:
var.subnet_id Enter a value:
This is no good; I want to pull the value from the VPC I just created, not enter it at the command prompt. Where do I specify that the data source is the resource that I just created in the previous code block?
I have heard that people create a separate file to hold Terraform variables. Is that what I should do here? It seems like it should be so basic to get an ID from one resource and use it in the next. Is there a one-liner to pass along this information?
