Monorepo vs multi-repo for Terraform - Hands-On Comparison

Monorepo vs Multi-repo for Terraform

📖 Scenario: You are working as a cloud engineer managing infrastructure as code using Terraform. Your team is deciding how to organize Terraform code: either in a single repository (monorepo) or multiple repositories (multi-repo). This project will guide you through creating simple Terraform configurations to understand the differences between monorepo and multi-repo setups.

🎯 Goal: Build two Terraform configurations: one representing a monorepo setup with multiple modules in one repo, and another representing a multi-repo setup with separate repos for each module. You will create the initial Terraform files, add configuration variables, apply core Terraform logic, and finalize the setup to see how infrastructure is organized differently.

📋 What You'll Learn

Create Terraform configuration files with exact resource names and variables

Use Terraform modules to separate infrastructure components

Configure backend and provider blocks correctly

Demonstrate monorepo and multi-repo structure differences

💡 Why This Matters

🌍 Real World

Organizing Terraform code effectively helps teams manage cloud infrastructure safely and efficiently, especially as projects grow.

💼 Career

Cloud engineers and DevOps professionals often decide between monorepo and multi-repo strategies to balance collaboration, code reuse, and deployment workflows.

1

Create initial Terraform configuration for monorepo

Create a Terraform file named main.tf with a provider block for AWS using region us-east-1. Then create a resource block for an AWS S3 bucket named monorepo-bucket.

Terraform

# Your code here

Need a hint?

Start by defining the AWS provider with the correct region. Then add a resource block for the S3 bucket with the exact name monorepo-bucket.

2

Add a variable for bucket name in monorepo

Create a variable named bucket_name with default value monorepo-bucket in a file named variables.tf. Then update the aws_s3_bucket.monorepo_bucket resource to use this variable for the bucket name.

Terraform

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.0"
    }
  }
}

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

resource "aws_s3_bucket" "monorepo_bucket" {
  bucket = var.bucket_name
  acl    = "private"
}

# Your code here

Need a hint?

Define the variable with the exact name bucket_name and default value monorepo-bucket. Update the bucket resource to use var.bucket_name.

3

Create a module for S3 bucket in multi-repo setup

Create a new directory named s3_bucket_module. Inside it, create a main.tf file with a resource block for an AWS S3 bucket named multi-repo-bucket. Also create a variable bucket_name with default multi-repo-bucket and use it in the resource.

Terraform

# Create directory s3_bucket_module and inside it create main.tf
# Your code here

Need a hint?

Inside the s3_bucket_module directory, define the S3 bucket resource and variable exactly as specified.

4

Use the S3 bucket module in multi-repo root configuration

In the root main.tf file of the multi-repo setup, add a module block named s3_bucket that uses the local path ./s3_bucket_module. Pass the variable bucket_name with value multi-repo-bucket to the module.

Terraform

# Add module block in root main.tf
# Your code here

Need a hint?

Define the module block with the exact name s3_bucket, source path, and pass the variable as shown.