Dheeraj Choudhary
Dheeraj Choudhary's Blog

Follow

Dheeraj Choudhary's Blog

Follow
Deploy AWS Launch Configuration & AutoScaling Group Using Terraform

Deploy AWS Launch Configuration & AutoScaling Group Using Terraform

Dheeraj Choudhary's photo
Dheeraj Choudhary
·Dec 12, 2022·

7 min read

Play this article

Table of contents

Welcome back to the series of Deploying On AWS Cloud Using Terraform 👨🏻‍💻. In this entire series, we will focus on our core concepts of Terraform by launching important basic services from scratch which will take your infra-as-code journey from beginner to advanced. This series would start from beginner to advance with real-life Usecases and Youtube Tutorials.

If you are a beginner for Terraform and want to start your journey towards infra-as-code developer as part of your DevOps role buckle up 🚴‍♂️ and let's get started and understand core Terraform concepts by implementing it...🎬

❗️❗️Pre-Requisite❗️❗️

1️⃣ Deploying On AWS Cloud Using Terraform Series Pre-Requisites

2️⃣ Deploy VPC, IGW & Associate [Mandatory]

3️⃣ Deploy only public subnet template from the below blog [Mandatory]

4️⃣ EC2 instance with Security group [Reference]

5️⃣ Deploy Target Group [Mandatory]

5️⃣ Terraform Naming Conventions & Best Practices

🔎Basic Terraform Configurations🔍

As part of the basic configuration we are going to set up 3 terraform files

  1. Providers File:- Terraform relies on plugins called "providers" to interact with cloud providers, SaaS providers, and other APIs.
    Providers are distributed separately from Terraform itself, and each provider has its own release cadence and version numbers.
    The Terraform Registry is the main directory of publicly available Terraform providers, and hosts providers for most major infrastructure platforms. Each provider has its own documentation, describing its resource types and their arguments.
    We would be using AWS Provider for our terraform series. Make sure to refer Terraform AWS documentation for up-to-date information.
    Provider documentation in the Registry is versioned; you can use the version menu in the header to change which version you're viewing.
provider "aws" {
  region                  = "var.AWS_REGION"
  shared_credentials_file = "<Your AWS Credentials File path>"
}
  1. Variables File:- Terraform variables lets us customize aspects of Terraform modules without altering the module's own source code. This allows us to share modules across different Terraform configurations, reusing the same data at multiple places.
    When you declare variables in the root terraform module of your configuration, you can set their values using CLI options and environment variables. When you declare them in child modules, the calling module should pass values in the module block.
variable "AWS_REGION" {
  default = "us-east-1"
}
#-------------------------Fetch VPC ID---------------------------------
data "aws_vpc" "GetVPC" {
filter {
    name   = "tag:Name"
    values = ["CustomVPC"]
          }
}
#-------------------------Variables For Autoscaling---------------------
variable "instance_type" {
  type = string
  default = "t2.micro"
}
variable "autoscaling_group_min_size" {
  type = number
  default = 2
}
variable "autoscaling_group_max_size" {
  type = number
  default = 3
}
variable "aws_key_pair" {
  type = string
  default = <File Path>
}
#-------------------------Fetch Public Subnets List----------------------
data "aws_subnet_ids" "GetSubnet_Ids" {
  vpc_id = data.aws_vpc.GetVPC.id
  filter {
    name   = "tag:Type"
    values = ["Public"]
  }
}
data "aws_subnet" "GetSubnet" {
  count = "${length(data.aws_subnet_ids.GetSubnet_Ids.ids)}"
  id    = "${tolist(data.aws_subnet_ids.GetSubnet_Ids.ids)[count.index]}"
}
#-------------------------Fetch Target Group ARN----------------------
data "aws_lb_target_group" "elb_tg" {
  arn  = var.elb_tg_arn
}
  1. Versions File:- It's always a best practice to maintain a version file where you specific version based on which your stack is testing and live on production.
terraform {
  required_version = ">= 0.12"
}

🎨 Diagrammatic Representation 🎨

image.png

Configure Security Group For Launch Configuration

The method acts as a virtual firewall to control your inbound and outbound traffic flowing in and out.

🔳 Resource

aws_security_group:- This resource is define traffic inbound and outbound rules on the subnet level.

🔳 Arguments

name:- This is an optional argument to define the name of the security group.
description:- This is an optional argument to mention details about the security group that we are creating.
vpc_id:- This is a mandatory argument and refers to the id of a VPC to which it would be associated.
tags:- One of the most important property used in all resources. Always make sure to attach tags for all your resources.
EGRESS & INGRESS are processed in attribute-as-blocks mode.

resource "aws_security_group" "asg_sg" {
  name        = "ASG_Allow_Traffic"
  description = "Allow all inbound traffic for asg"
  vpc_id      = data.aws_vpc.GetVPC.id

  ingress {
    from_port   = 443
    to_port     = 443
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }
  ingress {
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }
  ingress {
    from_port   = 8
    to_port     = 0
    protocol    = "icmp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port       = 0
    to_port         = 0
    protocol        = "-1"
    cidr_blocks     = ["0.0.0.0/0"]
  }
  tags = {
    Name = "terraform-asg-security-group"
  }
}

👨🏻‍💻Deploy Launch Config and AutoScaling group👨🏻‍💻

Before creating the Autoscaling group let's first define the launch configuration for EC2 instances that will be used by autoscaling later.

🔳 Resource

aws_launch_configuration:- This resource creates a launch configuration for EC2 instances that we are going to deploy as part of our autoscaling group.

🔳 Arguments

name_prefix:- This is an optional argument to create a unique name beginning with the specified prefix.
image_id:- This is an mandatory argument to mention image_id id based on which EC2 instance will be launched.
instance_type:- This is a mandatory argument to mention instance type for the EC2 instances like t2.small, t2.micro etc.
key_name:- This is an optional argument to enable ssh connection to your EC2 instance.
security_groups:- This is an optional argument to mention which controls your inbound and outbound traffic flowing to your EC2 instances inside a subnet.
user_data:- This is an optional argument to provide commands or scripts to be executed during the launch of the EC2 instance.
Lifecycle:- Lifecycle is a nested block that can appear within a resource block.
create_before_destroy:- when Terraform must change a resource argument that cannot be updated in place due to remote API limitations, Terraform will instead destroy the existing object and then create a new replacement object with the newly configured arguments.

resource "aws_launch_configuration" "launch_config_dev" {
  name_prefix                 = "webteir_dev"
  image_id                    = "ami-0742b4e673072066f"
  instance_type               = "${var.instance_type}"
  key_name                    = "${var.aws_key_pair}"
  security_groups             = ["${aws_security_group.asg_sg.id}"]
  associate_public_ip_address = true
  user_data                   = <<EOF
    #! /bin/bash
    sudo su
    sudo yum update
    sudo yum install -y httpd
    sudo chkconfig httpd on
    sudo service httpd start
    echo "<h1>Deployed EC2 Using ASG</h1>" | sudo tee /var/www/html/index.html
    EOF
  lifecycle {
    create_before_destroy = true
  }
}

🔳 Resource

aws_autoscaling_group:- This resource group resources for use so that it can be associated with load balancers.

🔳 Arguments

launch_configuration:- This is an optional argument to mention name of the launch configuration to be used.
min_size:- This is a mandatory argument to define the minimum size of the Autoscaling group.
max_size:-This is a mandatory argument to define the maximum size of the Autoscaling group.
target_group_arns:- This is an optional argument to define the target group arn to which EC2 can register.
vpc_zone_identifier:- This is an optional argument to define a list of subnet IDs to launch resources in.
tags:- One of the most important property used in all resources. Always make sure to attach tags for all your resources.

resource "aws_autoscaling_group" "autoscaling_group_dev" {
  launch_configuration = "${aws_launch_configuration.launch_config_dev.id}"
  min_size             = "${var.autoscaling_group_min_size}"
  max_size             = "${var.autoscaling_group_max_size}"
  target_group_arns    = ["${data.aws_lb_target_group.elb_tg.arn}"]
  vpc_zone_identifier  = "${data.aws_subnet.GetSubnet.*.id}"

  tag {
    key                 = "Name"
    value               = "autoscaling-group-dev"
    propagate_at_launch = true
  }
}

🔳 Output File

Output values make information about your infrastructure available on the command line, and can expose information for other Terraform configurations to use. Output values are similar to return values in programming languages.

output "asg_sg" {
  value       = aws_security_group.asg_sg.id
  description = "This is Security Group for autoscaling launch configuration."
}
output "aws_launch_configuration" {
  value       = aws_launch_configuration.launch_config_dev.id
  description = "This is ASG Launch Configuration ID."
}
output "autoscaling_group_dev" {
  value       = aws_autoscaling_group.autoscaling_group_dev.id
  description = "This is ASG ID."
}

🔊To view the entire GitHub code click here

1️⃣ The terraform fmt command is used to rewrite Terraform configuration files to a canonical format and style👨‍💻.

terraform fmt

2️⃣ Initialize the working directory by running the command below. The initialization includes installing the plugins and providers necessary to work with resources. 👨‍💻

terraform init

3️⃣ Create an execution plan based on your Terraform configurations. 👨‍💻

terraform plan

4️⃣ Execute the execution plan that the terraform plan command proposed. 👨‍💻

terraform apply -auto-approve

👁‍🗨👁‍🗨 YouTube Tutorial 📽

[Coming soon]

ELB (2).png

destroy.png

❗️❗️Important Documentation❗️❗️

⛔️ Hashicorp Terraform
⛔️ AWS CLI
⛔️ Hashicorp Terraform Extension Guide
⛔️ Terraform Autocomplete Extension Guide
⛔️ AWS Security Group
⛔️ AWS Launch Configuration
⛔️ AWS Autoscaling Group
⛔️ Lifecycle Meta-Argument

🥁🥁 Conclusion 🥁🥁

In this blog, we have configured the below resources
✦ AWS Security Group for the ASG Launch Configuration.
✦ AWS Launch Configuration.
✦ AWS Autoscaling Group.
I have also referenced what arguments and documentation we are going to use so that while you are writing the code it would be easy for you to understand terraform official documentation. Stay with me for the next blog.

📢 Stay tuned for my next blog.....

🎊**So, did you find my content helpful? If you did or like my other content, feel free to buy me a coffee. Thanks. **🎊

👨🏻‍💻Terraform GitHub Repository👨🏻‍💻

Did you find this article valuable?

Support Dheeraj Choudhary by becoming a sponsor. Any amount is appreciated!

See recent sponsors Learn more about Hashnode Sponsors
 
Share this