Infrastructure as Code Using Terraform 🚀

A hands-on, week-by-week learning series covering Infrastructure as Code (IaC) using HashiCorp Terraform — from fundamentals to advanced production patterns.

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📋 Table of Contents

• About This Repository
• Prerequisites
• Course Structure
  • Week 1 – Introduction to IaC with Terraform
  • Week 2 – State Management
  • Week 3 – Modules
  • Week 4 – CI/CD & Drift Detection
  • Week 5 – Terraform Cloud & Spacelift
• Getting Started
• Folder Structure
• Resources & Books
• Contributing
• License

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About This Repository

This repository is a structured, progressive learning path for anyone who wants to master Terraform for real-world infrastructure automation. Each week builds on the previous one, introducing new concepts through practical examples and hands-on labs.

Whether you are a developer, DevOps engineer, or cloud architect, this series will equip you with the skills to write, manage, and scale infrastructure code with confidence.

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Prerequisites

Before you begin, make sure you have the following installed and configured:

• Terraform CLI (v1.0+)
• AWS CLI configured with appropriate permissions
• A code editor (e.g., VS Code with the HashiCorp Terraform extension)
• Basic understanding of cloud computing concepts (AWS recommended)
• Git installed and a GitHub account

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Course Structure

Week 1 – Introduction to IaC with Terraform

📁 Week-1 introduction to Iac With Terraform

What You'll Learn:

• What Infrastructure as Code (IaC) is and why it matters
• Overview of Terraform: architecture, providers, and the HCL language
• Terraform workflow: init → plan → apply → destroy
• Writing your first Terraform configuration to provision AWS resources
• Understanding terraform.tfstate and what it does

Key Concepts:

• Providers and Resources
• Variables and Outputs
• Data Sources
• The Terraform Registry

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Week 2 – State Management

📁 Week-2 State Management

What You'll Learn:

• Deep dive into Terraform state and why it is critical
• Local vs. remote state storage
• Configuring an S3 backend with DynamoDB state locking
• State commands: terraform state list, mv, rm, pull, push
• Handling state drift and resolving conflicts

Key Concepts:

• Remote Backends (S3 + DynamoDB)
• State Locking and Consistency
• Importing existing infrastructure with terraform import
• Sensitive data in state files

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Week 3 – Modules

📁 Week-3 Modules

What You'll Learn:

• Why modules are the building blocks of reusable Terraform code
• Creating your own custom modules
• Using modules from the Terraform Public Registry
• Passing inputs and returning outputs from modules
• Module versioning and best practices for module design

Key Concepts:

• Module structure (main.tf, variables.tf, outputs.tf)
• Root module vs. child modules
• Module composition and nesting
• The source and version arguments

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Week 4 – CI/CD & Drift Detection

📁 Week-4 CI-CD Drift Detection

What You'll Learn:

• Integrating Terraform into CI/CD pipelines (GitHub Actions)
• Automating terraform plan and terraform apply safely
• What infrastructure drift is and why it happens
• Implementing automated drift detection using scheduled workflows
• Handling drift alerts and remediation strategies

Key Concepts:

• GitHub Actions workflows for Terraform
• terraform plan -detailed-exitcode for drift detection
• Storing plan artifacts and reviewing changes in Pull Requests
• Environment-based deployments (dev, staging, prod)
• OIDC-based authentication with AWS (no long-lived credentials)

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Week 5 – Terraform Cloud & Spacelift

📁 Week-5 Terraform Cloud & Spacelift

What You'll Learn:

• What Terraform Cloud (HCP Terraform) is and how it differs from the open-source CLI
• Setting up a Terraform Cloud organisation, workspaces, and VCS-driven workflows
• Remote state management and remote plan/apply execution in Terraform Cloud
• Introduction to Spacelift as a powerful alternative IaC management platform
• Connecting your GitHub repository to Spacelift stacks for GitOps-driven deployments
• Policy as Code with Sentinel (Terraform Cloud) and Spacelift policies
• Comparing Terraform Cloud vs Spacelift: when to use each

Key Concepts:

Feature	Terraform Cloud (HCP Terraform)	Spacelift
Remote State	✅ Native backend	✅ Managed state
VCS Integration	GitHub, GitLab, Bitbucket	GitHub, GitLab, Bitbucket, Azure DevOps
Policy as Code	Sentinel	OPA-based policies
Drift Detection	✅ Health assessments	✅ Built-in drift detection
Multi-IaC Support	Terraform / OpenTofu	Terraform, Pulumi, CloudFormation, Ansible
Self-hosted Agents	✅ Terraform Cloud Agents	✅ Spacelift private workers

Hands-On Labs:

1. Lab 5.1 – Terraform Cloud Setup: Create a free Terraform Cloud account, configure an organisation, link a VCS-connected workspace to this repository, and trigger a remote plan and apply.

2. Lab 5.2 – Remote State in Terraform Cloud: Migrate local state to a Terraform Cloud workspace backend and observe cross-workspace state sharing using terraform_remote_state.

3. Lab 5.3 – Sentinel Policy Enforcement: Write a Sentinel policy that prevents any EC2 instance from being provisioned with an instance type outside an approved list. Attach it to your Terraform Cloud workspace.

4. Lab 5.4 – Spacelift Stack: Create a Spacelift account, connect this repository, and configure a Stack that mirrors your Terraform Cloud workspace — including drift detection and approval-gated applies.

Terraform Cloud Backend Configuration:

# backend.tf
terraform {
  cloud {
    organization = "your-org-name"

    workspaces {
      name = "iac-terraform-week5"
    }
  }
}

Sample Sentinel Policy:

# policies/allowed-instance-types.sentinel
import "tfplan/v2" as tfplan

allowed_types = ["t3.micro", "t3.small", "t3.medium"]

ec2_instances = filter tfplan.resource_changes as _, rc {
  rc.type is "aws_instance" and
  rc.mode is "managed" and
  (rc.change.actions contains "create" or rc.change.actions contains "update")
}

violations = filter ec2_instances as _, instance {
  instance.change.after.instance_type not in allowed_types
}

main = rule {
  length(violations) is 0
}

Connecting Spacelift to GitHub:

# 1. Create a Spacelift account at https://spacelift.io
# 2. Install the Spacelift GitHub App on your repository
# 3. Create a new Stack in the Spacelift UI:
#    - VCS: GitHub → select this repository
#    - Project root: "Week-5 Terraform Cloud & Spacelift"
#    - Runner image: Default (includes Terraform)
#    - Set AWS credentials as Spacelift environment variables or use dynamic credentials
# 4. Trigger a tracked run — Spacelift will plan on every push and apply on merge to main

Key Takeaways:

• Terraform Cloud and Spacelift both solve the problem of running Terraform safely at scale — with remote execution, state management, and access control
• Sentinel (Terraform Cloud) and OPA policies (Spacelift) shift compliance checks left, preventing non-compliant infrastructure from ever being applied
• Spacelift's multi-IaC support and flexible policy engine make it a strong choice for organisations using more than just Terraform
• Both platforms support private/self-hosted agents for use inside private networks

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Getting Started

# 1. Clone the repository
git clone https://github.com/kodcapsule/Infrastructure-as-Code-Using-Terraform.git
cd Infrastructure-as-Code-Using-Terraform

# 2. Navigate to any week's folder
cd "Week-1 introduction to Iac With Terraform"

# 3. Initialize Terraform
terraform init

# 4. Preview the changes
terraform plan

# 5. Apply the configuration
terraform apply

# 6. Clean up resources when done
terraform destroy

⚠️ Important: Always review terraform plan output carefully before running terraform apply. Destroying resources may result in data loss.

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Folder Structure

Infrastructure-as-Code-Using-Terraform/
│                 
│
├── Books/                          
│
├── Week-1 introduction to Iac With Terraform/
├── Week-2 State Management/
├── Week-3 Modules/
├── Week-4  CI-CD Drift Detection/
├── Week-5 Terraform Cloud & Spacelift/
│
├── .gitignore
└── README.md

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Resources & Books

The Books/ directory contains curated reading materials to complement the weekly labs. Additional recommended resources:

• 📖 Terraform: Up & Running (3rd Edition) – Yevgeniy Brikman
• 📖 HashiCorp Terraform Documentation
• 📖 Terraform Best Practices
• 🎓 HashiCorp Learn
• ☁️ Terraform Cloud (HCP Terraform) Documentation
• 🚀 Spacelift Documentation
• 📜 Sentinel Policy Language

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Contributing

Contributions are welcome! If you find a bug, want to improve an example, or have ideas for additional labs:

1. Fork the repository
2. Create a new branch (git checkout -b feature/your-feature-name)
3. Make your changes and commit (git commit -m 'Add your message')
4. Push to your branch (git push origin feature/your-feature-name)
5. Open a Pull Request

Please follow the existing folder and naming conventions when adding new content.

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License

This project is licensed under the MIT License — see the LICENSE file for details.

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Made with ❤️ by kodcapsule