Objective

Apply all Terraform concepts to design and deploy a complete 3‑tier application infrastructure (web → app → database) with networking, scaling, load balancing, and CI/CD automation.

1 – Architecture Design

• Plan the 3‑tier architecture:
  • Presentation layer (Web): Public EC2 instances behind a load balancer.
  • Application layer (App): Private EC2 instances with auto‑scaling.
  • Data layer (DB): RDS instance in private subnet.
• Define networking boundaries (VPC, subnets, security groups).
• Decide on environment separation (dev, staging, prod).

2 – Networking

• Build a VPC with CIDR block.
• Create public and private subnets across availability zones.
• Configure Internet Gateway and NAT Gateway.
• Define security groups for web, app, and DB tiers.

3 – Compute

• Deploy EC2 instances for web and app tiers.
• Configure auto‑scaling groups for high availability.
• Use launch templates for consistent instance configuration.
• Apply user data scripts for bootstrapping.

4 – Database

• Deploy Amazon RDS (e.g., MySQL/PostgreSQL).
• Configure parameters (storage, backups, multi‑AZ).
• Place DB in private subnet with restricted access.
• Use Terraform variables for DB credentials (with Vault/Secrets Manager).

5 – Load Balancer

• Deploy Application Load Balancer (ALB).
• Configure listeners and target groups.
• Attach web/app instances to target groups.
• Enable health checks for resilience.

6 – CI/CD Pipeline

• Integrate Terraform with GitHub Actions / Jenkins / GitLab CI.
• Automate terraform plan and terraform apply on code changes.
• Use Terraform Cloud for remote state and policy enforcement.
• Add notifications for pipeline runs.

7 – Debugging

• Troubleshoot common Terraform errors:
  • State lock conflicts.
  • Provider authentication issues.
  • Resource drift.
  • Dependency cycles.
• Learn debugging commands: terraform plan, terraform state, terraform refresh.

The Hackers Notebook

This capstone project is where theory meets practice. By the end of this module, you’ll have built a complete, production‑ready 3‑tier application infrastructure with Terraform, automated through CI/CD, and hardened with debugging strategies. It’s the ultimate proof of your Terraform mastery.