Terraform : Creating two AWS EC2 instance and pass private IP from variable

Question

I am new in terraform, I have problem while creating ec2 instance, my condition is, I am passing private_Ips values from variable file (like IP pool) and creating two ec2 instance so when I run terraform apply first time it creates two ec2 instances, but when second time I run terraform apply it says IP already in use, its not going to take 3rd and 4th IP. I want on 2nd run it for it to take 3rd and 4th IPs. Below are my definitions. Could you please suggest:

var.tf

variable "private_ips" {

   default = {

    "0" = "x.x.x.x"

    "1" = "x.x.x.x"

    "2" = "x.x.x.x"

    "3" = "x.x.x.x"

  }

}

main.tf

  private_ip = "${lookup(var.private_ips,count.index)}"

Grzegorz Oledzki Grzegorz Oledzki · Accepted Answer · 2020-11-07T17:14:06

Terraform is a stateful tool. So, whenever it creates some pieces of infrastructure it keeps track of them (in what is called Terraform state). The whole idea is that if you run terraform apply the first time it creates some infrastructure. And any subsequent run just updates whatever has been created before (with whatever changes were applied in .tf files).

You might want to read up on workspaces whose idea is about using the same configuration (.tf files) against multiple independent copies of target infrastructure. Typically used for dev/test/prod kind of setups. It might be what you are after.

Terraform : Creating two AWS EC2 instance and pass private IP from variable

1 Answers