The Pros and Cons of Monorepos

Since I started as a software developer, I have always worked with polyrepos, which used to be the standard way for me to write code. If you want to create a new project, just create a new repository, configure your CI/CD pipelines, and you are done. It is simple to manage, but not until I worked on a contract job and was introduced to a new way to organize codebases: monorepos.

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Monorepo contains multiple projects in a single repository. All projects share the same codebases, dependencies and versioning system.

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A polyrepo is simply the opposite of a monorepo; in a polyrepo, each project has its own repository.

Let's take a look at some advantages and disadvantages of monorepos;

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Advantages of Monorepos

1. Better code sharing and reuse: With a monorepo, all code is stored in a single repository, making it easier to share and reuse code across different projects and teams. This can help reduce code duplication and improve development efficiency.

2. Simplified dependency management: Monorepos provide a centralized location for managing dependencies and versioning across different projects. This can help ensure that all code is using the same versions of dependencies and reduce conflicts.

3. Improved code consistency: With all code in a single repository, it's easier to enforce coding standards and best practices across different teams and projects. This can help ensure that code is consistent and maintainable over time.

4. Easier refactoring: Refactoring is simpler when all the code is in one repository, making it simpler to rework and restructure the code as necessary. This can aid in lowering technical debt and enhancing code quality.

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Disadvantages of Monorepos

1. Git performs poorly while working on complex projects: This challenge begins to show up on large applications with more commits and numerous developers working concurrently every day over the same repository. Given that Git uses a directed acyclic graph (DAG) to describe a project's history, this becomes particularly problematic. Git performance degrades as the history gets longer and more commits are made.

2. increased learning curve and challenges of inclusivity for newer developers: for a software project to be successful, the inclusion of all developers on the team is crucial. A monorepo structure could seem intimidating to newer developers. They may be unfamiliar with a list of separate projects housed in the same repository and may not know how to make a meaningful contribution. It can also be challenging for newer developers to understand the git history in a monorepo setup.

3. Access cannot be restricted: Giving fine-grained access control to external contributors or remote teams can be difficult. You must either offer access to the entire codebase or none at all.

4. Increased build time: The build process takes significantly longer than it would if many projects were built independently since there is so much code in one place.

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By having multiple projects in a single repository, monorepos can simplify code sharing, promote collaboration, and ensure consistency across development environments. However, monorepos also present challenges, such as longer build times and increased complexity, which should be carefully considered when deciding whether to adopt this approach. Understanding the pros and cons of monorepo is crucial to making an informed decision about whether it is the right approach for your software development needs.