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Chief Executive Officer

By Paul Tran

Paul Tran, Co-founder and CEO of Jaisda, brings over 30 years of IT experience, advising CEOs, CTOs, and CIOs on technology strategy and digital transformation initiatives across startups, mid-market businesses, and Fortune 500 companies.

When to Use a Monorepo: Benefits, Challenges, and Build System Deep Dive

Managing a large-scale project with multiple teams, services, and modules often presents developers with a crucial decision: Should we use a monorepo (single repository) or polyrepo (multiple repositories) approach? In this article, we’ll explore when to use a monorepo, what its key benefits and challenges are, and how to select the best build system—like Nx, Lerna, or Bazel to manage your monorepo efficiently.

What is a Monorepo?

A monorepo is a software development strategy where the code for multiple projects or services is stored within a single repository. In contrast to the polyrepo approach (where each project has its own repository), a monorepo enables teams to centralize their codebase, streamlining development workflows and CI/CD processes.

When Should You Consider a Monorepo?

  1. Tightly Coupled Services or Libraries: If your projects frequently share code (e.g., UI components, shared libraries, or utility functions), a monorepo makes sense. It ensures that teams can reuse code efficiently without version mismatches.

  2. Large, Cross-Functional Teams: Monorepos are ideal for large teams that work on multiple parts of an application. With a single repository, it’s easier to coordinate across teams and avoid siloed development.

  3. Consistent Standards and Practices: If you need to enforce code standards, testing frameworks**, and build pipelines across multiple projects, a monorepo allows for centralized configuration management.

  4. Unified CI/CD Pipeline: Monorepos can simplify your CI/CD setup by consolidating the build, test, and deployment processes into a single pipeline, saving you from maintaining multiple pipelines across repositories.

  5. Cross-Project Refactoring: Refactoring code that touches multiple services or projects becomes more straightforward in a monorepo because all the code is in one place, enabling developers to apply consistent updates across different projects without navigating multiple repos.

Challenges of Using a Monorepo

  1. Scalability: As the repository grows, managing builds, dependencies, and performance can become complex. This requires a robust build system to ensure scalability.

  2. Merge Conflicts and Large Pull Requests: With many teams working on different parts of the same codebase, merge conflicts can become more frequent, and changes can feel larger and harder to review.

  3. Tooling and Performance: Without the right tools, build times can increase, and dependency management can become harder in a large monorepo. Selecting a proper build system is crucial to mitigating these issues.

Build Systems for Monorepos: Nx, Lerna, Bazel

Choosing the right build system is critical when managing a monorepo. Here’s a deep dive into some of the best options available today.

1. Nx: Powerful and Modern Build System

Nx is a popular tool for managing monorepos, especially in JavaScript/TypeScript ecosystems. Originally developed by Nrwl, Nx provides a set of tools that enable efficient, incremental builds and tests in monorepos.

Key Features:

  • Incremental Builds: Nx supports caching and only rebuilds projects when necessary, ensuring faster build times.
  • Code Generation: Nx includes schematics to generate code, components, and libraries quickly.
  • Dependency Graph: It provides visualization of how different parts of your monorepo depend on each other, helping you understand which parts of your codebase will be affected by a change.
  • Plugin Support: Nx integrates well with multiple frameworks, including Angular, React, Node.js, and more.

When to Use Nx:

  • JavaScript/TypeScript Projects: Nx excels with JavaScript and TypeScript-based codebases.
  • Enterprise-Grade Monorepos: If you're building a large-scale web application or have multiple teams working on the same codebase, Nx's incremental build and caching mechanisms are incredibly useful.
  • Cross-Framework Projects: Nx is ideal when you're working with multiple frontend and backend frameworks in the same repo.

2. Lerna: Simplifying JavaScript Monorepos

Lerna is a tool that helps manage JavaScript/TypeScript monorepos. It allows you to split a large codebase into smaller packages (which can be published independently), while still maintaining everything in a single repository.

Key Features:

  • Versioning: Lerna enables independent versioning for each package, which is useful when some packages need to be updated more frequently than others.
  • Publishing: It integrates well with npm to publish multiple packages from a monorepo.
  • Scoped Changesets: Lerna supports running tests and builds only for the packages that were changed, improving build performance.

When to Use Lerna:

  • NPM Package Management: If you have a monorepo containing multiple npm packages that you want to maintain independently but within a single repo.
  • Small-to-Medium JavaScript Projects: Lerna works well for smaller-scale monorepos, but it doesn't offer the same level of incremental builds and caching that Nx does for larger projects.

3. Bazel: High Performance at Scale

Bazel is an open-source build tool developed by Google. It’s designed to handle extremely large codebases and is known for its speed and efficiency, making it a great choice for highly scalable monorepos.

Key Features:

  • Language Agnostic: Bazel supports many programming languages, making it ideal for polyglot codebases.
  • Remote Caching and Builds: It provides remote build execution and caching, ensuring that even very large builds can be handled efficiently.
  • Reproducible Builds: Bazel’s build process is deterministic, meaning it can recreate the exact same build output regardless of the machine it runs on.

When to Use Bazel:

  • Large-Scale, Multi-Language Monorepos: Bazel excels in managing large, polyglot codebases with many interdependencies.
  • High-Performance CI/CD: If your project requires quick, repeatable builds and tests at scale, Bazel’s remote execution and caching features make it a powerful choice.

Conclusion

Monorepos can bring significant benefits in terms of collaboration, code sharing, and unified development practices. However, they also require careful management, particularly when it comes to scaling and performance. Choosing the right build system—whether it's Nx for JavaScript/TypeScript projects, Lerna for npm packages, or Bazel for polyglot, large-scale systems—is crucial for ensuring your monorepo runs efficiently and scales with your needs.

If you're considering switching to a monorepo architecture, or if you're already using one and want to optimize your tooling, Jaisda can help you evaluate and implement the best solution for your unique project requirements.

Contact Us

Thinking of moving to a monorepo? Explore how monorepos and modern build tools can streamline your development process. Jaisda specializes in scalable software architectures and can help you optimize your development process with the right toolchain and repo strategy. Contact Jaisda today to discuss how we can help optimize your build system for maximum efficiency.