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Rahul Joshi
Rahul Joshi

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Day 18 - Infrastructure as Code (IaC) with Terraform

#masterclassdevsecops #terraform #webdev #developer

Modern cloud infrastructure is too complex to manage manually.

Imagine creating:

  • 10 EC2 instances
  • 5 VPCs
  • 20 Security Groups
  • 15 IAM Roles
  • 3 Load Balancers
  • Kubernetes Clusters

using only a cloud console.

It quickly becomes:

Slow
Error-Prone
Difficult to Scale
Impossible to Audit
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This is why Infrastructure as Code (IaC) became one of the most important practices in modern DevOps and Cloud Engineering.

🔗 Resources

What is Infrastructure as Code (IaC)?

Infrastructure as Code (IaC) is the practice of managing infrastructure through code instead of manually creating resources.

Instead of clicking buttons:

AWS Console
      ↓
Create EC2
      ↓
Create Security Group
      ↓
Create VPC
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You write:

resource "aws_instance" "web" {
  ami           = "ami-123456"
  instance_type = "t2.micro"
}
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And infrastructure gets created automatically.

Why Infrastructure as Code Matters

Before IaC, infrastructure management was painful.

Common problems included:

  • Manual mistakes
  • Configuration drift
  • Poor documentation
  • Difficult disaster recovery
  • Inconsistent environments

Example:

Developer Environment
        ↓
Works Perfectly
        ↓
Production Environment
        ↓
Different Configuration
        ↓
Application Fails
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IaC solves this problem by making environments reproducible.

Benefits of Infrastructure as Code

1. Consistency

Every environment is identical.

Dev
 ↓
QA
 ↓
Staging
 ↓
Production
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All built from the same code.

2. Version Control

Infrastructure becomes:

Git Commit
Pull Request
Code Review
Rollback
Audit Trail
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Infrastructure changes become trackable.

3. Automation

Entire environments can be created in minutes.

4. Disaster Recovery

If infrastructure is lost:

Git Repository
        ↓
terraform apply
        ↓
Infrastructure Restored
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5. Scalability

Large organizations can manage thousands of resources through code.

Infrastructure as Code Market Growth

Infrastructure automation has become a standard practice.

Today IaC is used by:

  • Cloud Engineers
  • DevOps Engineers
  • Platform Engineers
  • SRE Teams
  • Security Teams

Organizations running:

  • AWS
  • Azure
  • GCP
  • Kubernetes

almost always adopt some form of IaC.

Types of Infrastructure as Code

Declarative

You describe the desired state.

Example:

resource "aws_instance" "web" {
  instance_type = "t2.micro"
}
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Tool decides how to create it.

Examples:

  • Terraform
  • CloudFormation
  • Bicep

Imperative

You define step-by-step instructions.

Example:

create_vpc()
create_subnet()
create_ec2()
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Examples:

  • Pulumi
  • Custom automation scripts

Popular Infrastructure as Code Tools

1. Terraform

Most popular multi-cloud IaC tool.

Created by:

HashiCorp

Supports:

  • AWS
  • Azure
  • GCP
  • Kubernetes
  • VMware
  • GitHub
  • Hundreds of providers

2. AWS CloudFormation (CFT)

AWS-native IaC service.

Supports:

  • VPC
  • EC2
  • IAM
  • S3
  • RDS
  • Lambda

Example:

Resources:
  MyBucket:
    Type: AWS::S3::Bucket
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3. Azure Bicep

Microsoft's modern IaC language.

Simplifies Azure Resource Manager templates.

Example:

resource storage 'Microsoft.Storage/storageAccounts@2022-09-01' = {
  name: 'mystorage'
}
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4. Pulumi

Modern Infrastructure as Code.

Uses programming languages:

  • Python
  • Go
  • TypeScript
  • C#
  • Java

Example:

import pulumi_aws as aws

bucket = aws.s3.Bucket("my-bucket")
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difference

Why Terraform Dominates IaC

Terraform became the industry standard because:

One Language
        ↓
Multiple Clouds
        ↓
Single Workflow
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Engineers can manage:

  • AWS
  • Azure
  • GCP
  • Kubernetes

using one tool.

Terraform Architecture

architecture

Terraform Basics

Understanding Terraform starts with four key concepts:

  • Providers
  • Resources
  • Variables
  • State

Terraform Providers

Providers allow Terraform to communicate with platforms.

Examples:

AWS Provider
Azure Provider
Google Provider
Kubernetes Provider
GitHub Provider
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Example:

provider "aws" {
  region = "us-east-1"
}
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Terraform now knows where to create resources.

Terraform Resources

Resources are actual infrastructure components.

Examples:

EC2 Instance
S3 Bucket
VPC
Security Group
IAM Role
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Example:

resource "aws_s3_bucket" "demo" {
  bucket = "my-demo-bucket"
}
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Terraform will create:

AWS S3 Bucket
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Terraform Variables

Variables make code reusable.

Without variables:

instance_type = "t2.micro"
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With variables:

variable "instance_type" {}

instance_type = var.instance_type
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Now different environments can use:

Dev → t2.micro
QA → t3.small
Prod → t3.large
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Terraform State

Terraform keeps track of infrastructure using:

terraform.tfstate
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This file stores:

  • Resource IDs
  • Current state
  • Dependency mapping

Terraform compares:

Current State
        vs
Desired State
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and calculates required changes.

Terraform Workflow

Step 1

Write Code

resource "aws_instance" "web" {
  ami           = "ami-123456"
  instance_type = "t2.micro"
}
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Step 2

Initialize

terraform init
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Downloads providers.

Step 3

Validate

terraform validate
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Checks syntax.

Step 4

Preview

terraform plan
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Shows changes before execution.

Step 5

Apply

terraform apply
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Creates infrastructure.

Deep Terraform Example

Let's create a simple AWS infrastructure.

Provider 

provider "aws" {
  region = "us-east-1"
}
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Variable 

variable "instance_type" {
  default = "t2.micro"
}
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Security Group 

resource "aws_security_group" "web_sg" {

  name = "web-sg"

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }
}
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EC2 Instance 

resource "aws_instance" "web" {

  ami           = "ami-123456"
  instance_type = var.instance_type

  vpc_security_group_ids = [
    aws_security_group.web_sg.id
  ]

  tags = {
    Name = "Terraform-Web"
  }
}
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What Happens Behind the Scenes?

Behined the Scene

Terraform File Structure

Typical project:

terraform-project/

├── main.tf
├── variables.tf
├── outputs.tf
├── terraform.tfvars
└── providers.tf
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Best Practices

Use Remote State

Store state in:

S3
Azure Storage
GCS
Terraform Cloud
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Never store production state locally.

Use Modules

Avoid repeating code.

module "vpc" {
  source = "./modules/vpc"
}
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Use Version Control

Infrastructure should always live in Git.

Enable Code Reviews

Treat infrastructure like application code.

Separate Environments 

Dev
QA
Staging
Production
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should have separate state files.

Infrastructure as Code in DevOps Pipeline 

Developer Pushes Terraform
          ↓
Pull Request
          ↓
Code Review
          ↓
terraform validate
          ↓
terraform plan
          ↓
Security Scan
          ↓
terraform apply
          ↓
Infrastructure Created
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Security Considerations

Never store:

AWS Keys
Passwords
Tokens
Secrets
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inside Terraform code.

Use:

  • AWS Secrets Manager
  • Azure Key Vault
  • HashiCorp Vault

instead.

Final Thoughts

Infrastructure as Code transformed how cloud infrastructure is managed.

Instead of:

Manual Infrastructure
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we now have:

Version Controlled Infrastructure
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Among all IaC tools:

  • Terraform dominates multi-cloud environments
  • CloudFormation is ideal for AWS-centric teams
  • Bicep is excellent for Azure
  • Pulumi is attractive for developers who prefer real programming languages

For anyone pursuing:

  • DevOps
  • Cloud Engineering
  • Platform Engineering
  • Site Reliability Engineering

Infrastructure as Code is no longer optional—it is a fundamental skill of modern cloud operations.

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