Terraform AWS Autoscaling

📐 Naming Convention

Common variables referenced in naming standards

Variable	RegExp	Example
<availability_zone>	[a-z]{2}-[a-z]{1,}-[1-2][a-f]	us-east-1a, us-west-2c, eu-west-1a, ap-northeast-1c

---

📐 AWS - Resource Naming Standards

• ALB

AWS Resource	Resource Naming	Comment	Example
ALB	<app_name>-alb-private	Tag Tier = private	web-api-alb-private
	<app_name>-alb-public	Tag Tier = public	web-api-alb-public
ALB Target group	<app_name>-<protocol>		web-api-alb-http, web-api-alb-https
ALB Security Groups	<app_name>-alb		web-api-alb

• ASG

AWS Resource	Resource Naming	Comment	Example
ASG Security Groups	<app_name>		web-api
ASG Launch Config	<app_name>-lc-<timestamp>		web-api-lc-1537774225
ASG Launch Template	<app_name>-lt-<timestamp>		web-api-lt-1537774225

---

🔮 Terraform Discovery module

If you followed the naming conventions listed in terraform-aws-vpc you will find it useful to use this terraform-aws-discovery module. The idea of using a discovery module is to centralize datasource usage in a central place and keep the source code DRY.

Here is an example usage:

module "discovery" {
  source              = "github.com/Lowess/terraform-aws-discovery"
  aws_region          = var.aws_region
  vpc_name            = var.vpc_name
  ec2_ami_names       = ["<AMI-NAME>"]
  ec2_ami_owners      = "<TEACHER-ACCOUNT-ID>"
  ec2_security_groups = [...]
}

☝️ If you do not what to use this module you are free to redefine the datasources you need but keep in mind that you will be rebuilding the wheel 🎡

---

1. Create an AWS ALB

Let's create an ALB and the related resources needed (security groups, listeners and target groups).

• aws_lb
• aws_lb_target_group
• aws_lb_listener
• aws_security_group
• aws_security_group_rule

2. Create the AWS Autoscaling group

• aws_security_group
• aws_security_group_rule
• aws_launch_template
• aws_autoscaling_group

3. Create policies to make the AWS Autoscaling group scale in/out

• Visit the Cloudwatch service and discover what this service does

☝️ Think about what's the best metric to use in order to adjust the size of the Autoscaling group

• aws_autoscaling_policy