What is a Monorepo

Monorepo

A monorepo is a version control strategy where multiple projects, often including libraries, applications, and services, are stored in a single repository. This approach contrasts with a multirepo (multiple repositories) strategy, where each project or component is stored in its own repository.

Key Concepts of Monorepos

1. Unified Codebase
In a monorepo, all projects and components share a unified codebase. This means that any changes made are immediately available to all related projects, facilitating synchronised updates and reducing the risk of version mismatches.

2. Dependency Management
Monorepos simplify dependency management by centralising dependencies in one place. Developers can manage shared libraries and tools more efficiently, ensuring consistency across projects.

3. Code Reuse
With all code housed in a single repository, code reuse becomes more straightforward. Common utilities and modules can be easily shared and maintained, reducing duplication and promoting best practices.

4. Simplified Collaboration
Monorepos foster collaboration by providing a single source of truth. Team members can see the entire project landscape, understand interdependencies, and contribute across multiple projects without switching contexts.

Pros of Monorepos

• Easier to ensure all parts of the codebase are compatible with each other since they are developed together.

• Reduces the complexity of managing dependencies between projects. All projects can share common libraries and components without needing to manage these dependencies across multiple repositories.

• Promotes sharing of code between projects, which can lead to more efficient development and maintenance.

• Large-scale refactoring and architectural changes are easier to perform across the entire codebase, ensuring consistency and reducing technical debt. Easier to enforce consistent development practices, tools, and configurations across all projects.

Cons of Monorepos

• As the repository grows, performance can degrade. Large repositories can become unwieldy, slow to clone, and difficult to navigate.

• Operations like merging, rebasing, and history searches can become more complex and time-consuming.

• Fine-grained access control becomes more challenging. It’s harder to restrict access to specific parts of the codebase when everything is in a single repository.

Use Cases for Monorepos

1. Large-Scale Applications
Organisations developing large-scale applications with multiple interconnected components can benefit from monorepos. For example, companies like Google and Facebook use monorepos to manage their extensive codebases, enabling seamless integration and deployment.

2. Microservices Architecture
In a microservice architecture, where services are designed to be loosely coupled but often need to interact, a monorepo can help maintain consistency and facilitate integration testing. Shared libraries and APIs can be updated and versioned together.

3. Multi-Platform Development
When developing applications for multiple platforms (e.g., web, mobile, desktop), a monorepo can centralise shared logic and components, reducing duplication and ensuring consistency across different platform versions.

Comparison of Features: PNPM Workspaces vs NX vs TurboRepo