Infrastructure as Code (IaC)

Terraform

Terraform Installation on Ubuntu/Debian:

Commands:

wget -O - https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list

sudo apt update && sudo apt install terraform

AWS CLI Installation on Ubuntu:

Commands:

curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"

unzip awscliv2.zip

sudo ./aws/install

Kubectl Installation on Ubuntu:

Commands:

curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"

Step-by-Step Configuration Guide with AWS EC2 Instance

1. Main Terraform Configuration:

main.tf

Terraform Configuration Example:

terraform { 
  required_providers { 
  aws = {
    source = "hashicorp/aws" 
    version = "~> 4.16"
    }
  }
  required_version = ">= 1.2.0"
}

provider "aws" { 
  region = "us-west-2"
}

resource "aws_instance" "app_server" { 
  ami = "ami-08d70e59c07c61a3a" 
  instance_type = "t2.micro"
  tags = {
    Name = var.instance_name
  }
}

2. Input Variables:

variables.tf

Example: hcl

variable "instance_name" {
  description = "Value of the Name tag for the EC2 instance"
  type = string
  default = "ExampleAppServerInstance" }

3. Output Values:

outputs.tf:

Example: hcl

output "instance_id" {
  description = "ID of the EC2 instance"
  value = aws_instance.app_server.id
}

output "instance_public_ip" {
  description = "Public IP address of the EC2 instance" 
  value = aws_instance.app_server.public_ip
}

4. Running the Configuration:

Initialize Terraform:

terraform init

Apply the Configuration:

terraform apply

Note

Confirm by typing yes when prompted.

Inspect Output Values:

terraform output

Destroy the Infrastructure:

terraform destroy

Terraform Advanced Configuration Use Cases

1. Provider Configuration:

provider "aws" { 
  region = "us-west-2"
}

2. Resource Creation:

resource "aws_instance" "example" { 
  ami = "ami-0c55b159cbfafe1f0" 
  instance_type = "t2.micro"
  tags = {
    Name = "ExampleInstance"
  }
}

3. Variable Management:

variable "region" { 
  default = "us-west-2"
}

provider "aws" { 
  region = var.region
}

4. State Management:

Example for using remote state in S3:

terraform {
  backend "s3" {
    bucket = "my-tfstate-bucket"
    key = "terraform/state"
    region = "us-west-2"
    encrypt = true
    dynamodb_table = "terraform-locks"
  }
}

5. Modules:

module "vpc" {
    source = "terraform-aws-modules/vpc/aws"
    name = "my-vpc"
    cidr = "10.0.0.0/16"
    azs = ["us-west-2a", "us-west-2b"]
    public_subnets = ["10.0.1.0/24", "10.0.2.0/24"]
    private_subnets = ["10.0.3.0/24", "10.0.4.0/24"] }

Terraform Commands Cheat Sheet

terraform init - Initializes the Terraform configuration.
terraform fmt - Formats configuration files.
terraform validate - Validates the configuration files.
terraform plan - Previews changes to be applied.
terraform apply - Applies the changes to reach the desired state.
terraform destroy - Destroys the infrastructure and removes it from the state.
terraform show - Displays the current state of resources.
terraform state list - Lists resources in the current state.
terraform taint <resource> - Marks a resource for recreation.
terraform import <resource> <resource_id> - Imports existing resources into Terraform.
terraform providers - Lists the providers used in the configuration.

Terraform Best Practices

Use Version Control to manage your Terraform code.
Break your code into Modules for reusability.
Use Remote State (e.g., AWS S3, Terraform Cloud) to store state files.
Always run terraform plan before terraform apply.
Use terraform fmt & terraform validate to ensure code correctness.
Avoid hardcoding secrets; use environment variables or secret management tools.
Keep configurations modular and well-documented.

CloudFormation (stacks, templates)

1. CloudFormation Concepts

Stack - A group of AWS resources defined in a template.
Template - /JSON file defining resources and configurations.
StackSet - Deploys stacks across multiple accounts and regions.
Change Set - Previews updates before applying changes.
Rollback - Automatic stack rollback if an error occurs.
Drift Detection - Identifies manual changes made outside CloudFormation.

2. CloudFormation Template Example

AWSTemplateFormatVersion: "2010-09-09"
Description: "Basic AWS CloudFormation Example"
Resources:
  MyBucket:
    Type: "AWS::S3::Bucket"
  MyEC2Instance:
    Type: "AWS::EC2::Instance"
    Properties:
      InstanceType: "t2.micro"
      ImageId: "ami-0abcdef1234567890"
Outputs:
  InstanceID:
    Description: "The Instance ID"
    Value: !Ref MyEC2Instance

3. CloudFormation CLI Commands

Stack Operations

aws cloudformation create-stack --stack-name my-stack --template-body file://template

aws cloudformation update-stack --stack-name my-stack --template-body file://template

aws cloudformation delete-stack --stack-name my-stack

Viewing Stack Details

aws cloudformation describe-stacks --stack-name my-stack

aws cloudformation list-stack-resources --stack-name my-stack

aws cloudformation describe-stack-events --stack-name my-stack

Change Set (Preview Changes)

aws cloudformation create-change-set --stack-name my-stack --template-body file://template. --change-set-name my-change-set

aws cloudformation describe-change-set --stack-name my-stack --change-set-name my-change-set

aws cloudformation execute-change-set --stack-name my-stack --change-set-name my-change-set

Drift Detection

aws cloudformation detect-stack-drift --stack-name my-stack

aws cloudformation describe-stack-drift-detection-status--stack-name my-stack

4. CloudFormation Best Practices

Use Parameters for Flexibility
Define parameters to make templates reusable:

Parameters:
  InstanceType:
    Type: String
    Default: "t2.micro"
    AllowedValues: ["t2.micro", "t2.small", "t2.medium"]

Use Mappings for Region-Specific Configurations

Mappings:
  RegionMap:
    us-east-1:
      AMI: "ami-12345678"
    us-west-1:
      AMI: "ami-87654321"

Use Conditions for Conditional Resource Creation

Conditions:
  IsProd: !Equals [!Ref "Environment", "prod"]
Resources:
  MyDatabase:
    Type: "AWS::RDS::DBInstance"
    Condition: IsProd

Use Outputs to Export Values

Outputs:
  S3BucketName:
    Description: "Name of the created S3 bucket"
    Value: !Ref MyBucket
    Export:
      Name: MyBucketExport

Use Nested Stacks for Large Templates

Note

Break large stacks into smaller, reusable nested stacks.

5. CloudFormation Troubleshooting

Stack creation fails - Check describe-stack-events for error details.
Parameter validation error - Ensure correct parameter types and values.
Rollback triggered - Check logs and describe-stack-events to debug.
Resources stuck in DELETE_FAILED - Manually delete dependencies before retrying.
Template validation error - Use aws cloudformation validate-template --template-body file://template to validate the template.