"Unifying Codebases: The Pros and Cons of Monorepo vs. Polyrepo Strategies"

What is Monorepo and How Does It Differ from Polyrepo?

Monorepo is a software development strategy that involves storing multiple projects or codebases that share a lot of code in a single repository. The term monorepo stands for monolithic repository, as opposed to polyrepo, which means having multiple repositories for different projects.

Polyrepo vs Monorepo

Polyrepo is the conventional way of developing software, where each team, application, or project has its own repository. Usually, each repository produces a single build artifact and has a simple build pipeline.

However, polyrepo has some drawbacks, such as:

• It can be difficult to share code across different repositories, especially if they use different languages, frameworks, or tools. Developers may need to use dependency managers, package managers, or submodules to manage the shared code.

• Developers may end up copying and pasting code from one repository to another, or creating multiple versions of the same code. This can lead to inconsistency, redundancy, and maintenance issues.

• When a shared library or a common dependency changes, developers may need to update all the repositories that use it. This can be time-consuming and error-prone, especially if there are breaking changes or compatibility issues.

• Different repositories may use different tools for coding, testing, building, deploying, or monitoring. This can make it hard to enforce consistent standards, best practices, or quality across the projects.

The main reason why many teams prefer polyrepo is team autonomy. Teams want to have control over their own code, decisions, and processes. They want to choose what libraries they use, when they deploy their apps or libraries, and who can contribute to or use their code. They also want to avoid dependencies or conflicts with other teams or projects.

Monorepo aims to solve these problems by storing all the code in one place. Some of the benefits of monorepo are:

• Developers can easily create new projects or modules within the same repository, without having to set up a new repository, configure permissions, or install dependencies.

• Developers can make changes to multiple projects or modules in a single commit, ensuring that they are always in sync and consistent. This also simplifies code reviews and version control.

• Developers can use the same version of the code, libraries, dependencies, and tools across all the projects. This eliminates the need for dependency management or package management tools and reduces the risk of version conflicts or mismatches.

• Developers can easily switch between different projects or modules within the same repository, without having to clone a new repository, install new dependencies, or learn new tools.

Challenges of Monorepo

Monorepo is not a silver bullet for software development. It also has some challenges and trade-offs that developers should be aware of, such as:

• Everyone who has access to the repository can see all the code in it. There is no way to limit access to certain parts of the code that are irrelevant or sensitive for some users.

• Since there is a lot of code in one place, building the whole repository can take a long time compared to building separate projects. Developers may need to use incremental builds, parallel builds, or caching techniques to speed up the build process.

• Git is not designed to handle large-scale monorepo projects well. Since there is a lot of code and commits in one place, Git's performance can become slow as the history grows. Developers may need to use alternative tools or strategies to manage the Git history.

Tools for Monorepo

There are several tools available for managing monorepo projects. These tools provide various features and functionalities such as creating and organizing packages and dependencies, building and testing the code, publishing and deploying the artifacts, etc. Some of the popular tools are:

• Lerna is a tool for managing JavaScript projects with multiple packages. It helps developers create new packages, test and verify them, and publish them to npm.

• Yarn Workspaces is a feature of Yarn that allows developers to manage multiple packages within a single repository. It helps developers install and link dependencies across packages and run scripts on them.

• Rush is a tool for managing monorepo projects with multiple applications. It helps developers organize applications into projects and manage dependencies between them.

• Nx: Nx is a tool for managing Angular and React projects within a monorepo. It helps developers create applications and libraries using Angular CLI or React CLI and share code between them.

• TurboRepo is an open-source tool for managing large-scale monorepo projects. It uses caching and incremental builds to speed up the development process and reduce build times. It also supports multiple languages and frameworks such as Java, Python, and JavaScript.

Conclusion

Monorepo and polyrepo are two different strategies for hosting and managing code through Git. Both have their pros and cons, and there is no definitive answer to which one is better. The choice depends on various factors, such as the size, complexity, and nature of the projects, the preferences and needs of the teams, and the availability and suitability of the tools.

Polyrepo offers more autonomy and flexibility for teams, but also introduces more challenges for code sharing, consistency, and maintenance. Monorepo offers more visibility and collaboration for teams, but also requires more discipline and infrastructure to manage the code.

Developers should weigh the benefits and drawbacks of each approach and decide which one fits their goals and workflows better. They should also be aware of the tools and techniques that can help them implement and optimize their chosen strategy.

References:

You can see more information about MonoRepo in monorepo.tools.