Last modified: June 11, 2024

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Monorepos

A monorepo is a single repository that contains all the code for a project, including multiple applications, libraries, and other dependencies. Monorepos are more suitable for large, monolithic projects where there is a need for close collaboration and frequent code reuse.

+---------------------------------------+
|                                       |
|             MONOREPO                  |
|                                       |
|  +-------+   +-------+   +-------+    |
|  | Proj1 |   | Proj2 |   | Proj3 |    |
|  +-------+   +-------+   +-------+    |
|                                       |
|  Shared Libraries & Dependencies      |
|                                       |
+---------------------------------------+

Advantages

1. Centralized Collaboration: All code is in one place, promoting seamless cooperation and code reuse. Teams can easily collaborate on changes without having to juggle multiple repositories.
2. Unified Dependency Management: Changes to shared dependencies are made just once, eliminating the inconsistencies of managing them across several repositories.
3. Facilitated Refactoring: As the code is centralized, global changes or refactors can be executed more efficiently, with a clear understanding of potential side effects.
4. Optimized Build and Test Times: With everything in one location, build and test pipelines can be more efficiently organized, potentially leading to quicker integrations.

Disadvantages

1. Potential Git Slowdowns: As the repository grows, Git operations (like cloning or fetching updates) may become slower, especially for developers without a fresh copy.
2. Complexity of Branch Management: Maintaining clarity among numerous branches can become challenging, increasing the risk of merge conflicts and integration issues.
3. Tight Coupling Risk: The ease of code sharing might inadvertently promote tight coupling between components or services that should remain loosely coupled.
4. Steep Learning Curve: New team members might find it daunting to navigate and understand a vast monorepo, potentially hampering their onboarding process.
5. Advanced CI/CD Needed: Given the extensive codebase, continuous integration and delivery tools might require more sophisticated configurations to handle the monorepo efficiently.
6. Risks with Force Pushes: An accidental force push or a corrupted master/main branch can have far-reaching implications, affecting every part of the project.

When to Use

• Large, Cohesive Projects: A monorepo might be apt for expansive, monolithic projects that benefit from tight integration and collaboration.
• Unified Team Structure: Monorepos can be advantageous when a singular team or closely-knit teams manage the entirety of the code, ensuring consistent code quality and practices.

Multirepos

A multirepo is a repository for each project, with each repository containing the code and dependencies for that project. Multirepos are more suitable for projects that are divided into multiple, independent components or services.

+-------+   +-------+   +-------+
|       |   |       |   |       |
| Repo1 |   | Repo2 |   | Repo3 |
|       |   |       |   |       |
| Proj1 |   | Proj2 |   | Proj3 |
|       |   |       |   |       |
+-------+   +-------+   +-------+

+--------------------------------------+
|   Shared Libraries & Dependencies    |
+--------------------------------------+

Advantages

1. Clear Versioning: Each service or component can be versioned independently, allowing for detailed tracking of changes and easier dependency management.
2. Enhanced Git Performance: Individual code checkouts and pulls remain lean, ensuring swift Git operations regardless of the overall project size.
3. Facilitated Team Autonomy: Teams can focus on their specific components without the need to navigate or understand the entire codebase, leading to potential productivity boosts.
4. Increased Flexibility: With autonomy comes the freedom for teams to make decisions tailored to their component, potentially resulting in innovative solutions and faster development cycles.

Disadvantages

1. Dependency Coordination: It becomes crucial to harmonize dependencies and libraries used across distinct services or components, which can be challenging.
2. Risk of Siloed Development: Separate repositories can sometimes lead to teams working too independently, potentially leading to code redundancies and a reduction in cross-team collaboration.
3. Code Reuse Challenges: Sharing common code or utilities across different repositories often requires added effort, potentially slowing down the development process.
4. Complex Deployment Orchestration: Deploying interconnected services from different repositories demands more sophisticated coordination, possibly complicating release processes.

When to Use

• Modular Projects: Multirepo setups thrive in projects segmented into multiple, independent components or services that might evolve at their own pace.
• Diverse Team Structures: Projects with multiple teams, each focusing on different aspects or components, might benefit from a multirepo approach. This is especially true when different parts of a project demand their own deployment cycles.