VPC Project using Terraform¶

This project demonstrates the core Terraform concepts by provisioning a Virtual Private Cloud (VPC) on AWS.

Step-01: Terraform Concepts Covered¶

We’ll learn how to create a VPC using Terraform step by step while understanding core language constructs.

Terraform Block
Provider Block
Input Variables
Local Values
Data Sources
Resource Blocks
Outputs
State files (local)
Basic Terraform commands: init, validate, plan, apply, destroy

AWS VPC Architecture¶

Terraform Basic Concepts

AWS VPC Traffic Flow¶

Terraform Execution Flow

AWS VPC - Public and Private Subnet Routes¶

Terraform Execution Flow

Step-02: Project Structure¶

File	Description
`c1-versions.tf`	Defines required Terraform version and AWS provider block
`c2-variables.tf`	Declares input variables used throughout the config
`c3-datasources-and-locals.tf`	Contains AWS region data source and local values
`c4-vpc.tf`	Main resource block that provisions the AWS VPC and subnets
`c5-outputs.tf`	Defines output values like VPC ID, subnet IDs, etc.

Step-03: `c1-versions.tf` – Terraform & Provider Block¶

Terraform Block¶

Locks Terraform version and AWS provider.

terraform {
  required_version = ">= 1.0.0"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = ">= 6.0"
    }
  }
}

Providers Block¶

Configures AWS region via variable (var.aws_region).

provider "aws" {
  region = var.aws_region
}

Step-04: `c2-variables.tf` – Input Variables¶

Defines configurable parameters like:

aws_region
VPC CIDRs
Subnet CIDRs
Environment tags

This makes the code reusable across different environments.

Step-05: `c3-datasources-and-locals.tf` – Data Sources & Locals¶

Uses data "aws_region" to fetch current AWS region details.
Uses locals block to create dynamic names and reuse logic (like resource naming conventions).

Step-06: `c4-vpc.tf` – VPC Resource Block¶

Creates:

VPC
Internet Gateway
Route Table
Public Subnets
Route Table and
Route Table Associations

Each resource is tagged using input variables and locals.

Step-07: `c5-outputs.tf` – Output Values¶

Displays key outputs after terraform apply, such as:

VPC ID
Public subnet IDs
AWS region used

This helps in referencing outputs in other Terraform modules or debugging.

Step-08: Terraform Commands (Basics)¶

Command	Purpose
`terraform init`	Initialize working directory
`terraform validate`	Validate configuration files
`terraform plan`	Show execution plan
`terraform apply`	Apply the configuration
`terraform destroy`	Tear down all infrastructure
`terraform output`	Show outputs defined

# Change Directory
cd terraform-manifests

# Terraform Initialize
terraform init 

# Terraform Validate
terraform validate

# Terraform Plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

¶

Step-09: Verify VPC Resources created¶

Go to AWS Console -> VPC
VPC
Subnets
NAT Gateway
INTERNET Gateway
Route Tables

Step-10: State Management¶

This project uses local state file (terraform.tfstate), stored in the working directory. Terraform Local State File

# Change Directory
cd terraform-manifests

# List Files
ls -lrt
Observation: You will find the file `terraform.tfstate`

# Review terraform.tfstate
cat terraform.tfstate

Step-11: Inspect State with `terraform show`¶

Purpose: The terraform show command lets you inspect the Terraform state in a human-readable or machine-readable format.
This is especially useful for:
Verifying what resources exist after an apply
Debugging issues by checking real resource attributes
Reviewing values stored in the state file

Comparing values between runs

# Terraform show command
terraform show

What terraform show Doesn't Do
It doesn't show future changes — use terraform plan for that.
It doesn't modify infrastructure or state.

Step-12: Terraform State Command (List Only)¶

In this step, we’ll explore how to view which resources are currently being tracked in your Terraform state file.

Why Is This Important?¶

After you run terraform apply, Terraform stores metadata about every resource it creates in a state file (terraform.tfstate). To see a summary of what’s being managed, you can use the terraform state list command.

Command: `terraform state list`¶

terraform state list

This will output a list like:

aws_vpc.main
aws_subnet.public[0]
aws_subnet.public[1]
aws_internet_gateway.main

Each line represents a resource tracked by Terraform.

When is this useful?¶

Quickly confirm all resources created
Helps debug or verify module outputs
Understand how Terraform names internal references (e.g., aws_subnet.public[0])

⚠️⚠️⚠️ Note:¶

In this course, we’re only focusing on listing state. Terraform has other advanced state commands (like state show, rm, mv, pull, etc.), but those are used in complex refactoring scenarios and are out of scope for now.

Step-13: Clean-Up¶

Let’s clean up the current infrastructure created by this project.

Destroy Resources Using Terraform¶

# Navigate to the VPC project directory
cd 05_02_vpc/terraform-manifests

# Destroy all resources created by this project
terraform destroy -auto-approve

⚠️ This command will delete all AWS resources provisioned by this configuration — including the VPC, subnets, route tables, and more.