Autoscaling Groups with terraform on AWS Part 1: Basic Steps

So you want to create an autoscaling group on AWS using terraform. The following are the minimum steps in order to achieve so.



Before writing the actual code you shall specify the aws terraform provider as well as the region on the file.

provider "aws" {
  version = "~> 2.0"
  region  = "eu-west-1"

terraform {
  required_version = "~>0.12.0"

The next step would be to define some variables on the file.

variable "vpc_id" {
  type = string
  default = "your-vpc-id"

variable "launch_configuration_name" {
  type = string
  default = "launch_configuration_name"

variable "auto_scalling_group_name" {
  type = string
  default = "auto_scalling_group_name"

variable "image_id" {
  type = string
  default =  "image-id-based-on-the-region"

variable "instance_type" {
  type = "string" 
  default = "t2.micro"

Then we are going to have the autoscalling group configuration on the file.

data "aws_subnet_ids" "subnets" {
  vpc_id = var.vpc_id

data "aws_subnet" "subnet_values" {
  for_each = data.aws_subnet_ids.subnets.ids
  id       = each.value

resource"aws_launch_configuration" "launch-configuration" {
  name = var.launch_configuration_name
  image_id = var.image_id
  instance_type = var.instance_type

resource "aws_autoscaling_group" "autoscalling_group_config" {
  name = var.auto_scalling_group_name
  max_size = 3
  min_size = 2
  health_check_grace_period = 300
  health_check_type = "EC2"
  desired_capacity = 3
  force_delete = true
  vpc_zone_identifier = [for s in data.aws_subnet.subnet_values:]

  launch_configuration =

  lifecycle {
    create_before_destroy = true

Let’s break them down.
The vpc id is needed in order to identify the subnets used by your autoscaling group.
Thus the value vpc_zone_identifier shall derive the subnets from the vpc defined.

Then you have to create a launch configuration.
The launch configuration shall specify the image id which is based on your region and the instance type.

To execute this provided you have your aws credentials in place you have to do initialize and then apply

> terraform init
> terraform apply

On the next tutorial we shall focus on adding an instance security group and a boot script.


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