Mono Repo - The Google Way

In software engineering, the choice between using a mono repo approach and a multi repo approach is an important one, as it can have a significant impact on the design, development, and maintenance of the software.

A mono repo approach is a way of organizing the codebase of a software system in which all of the code is stored in a single repository. This means that all of the different components of the system, including the application code, libraries, and dependencies, are all stored together in a single location.

A multi repo approach, on the other hand, is a way of organizing the codebase in which each component of the system is stored in its own separate repository. This can allow for more granular control and isolation of the different components, but it can also add complexity and overhead to the development process.

One of the main advantages of a mono repo approach is that it can simplify the development process. Because all of the code is stored in a single repository, it is easier to see how the different components of the system fit together, and it is also easier to make changes that affect multiple components of the system.

Additionally, a mono repo approach can make it easier to manage dependencies and ensure that all of the components of the system are using consistent versions of the libraries and other dependencies that they rely on.

However, one of the main disadvantages of a mono repo approach is that it can be more difficult to scale and manage. Because all of the code is stored in a single repository, it can become large and unwieldy over time, which can impact the performance of the version control system and make it more difficult to work with.

Additionally, because all of the code is stored together, it can be more difficult to isolate and manage individual components, which can make it harder to make changes without affecting the entire system.

In contrast, one of the main advantages of a multi repo approach is that it can provide more granular control and isolation of the different components of the system. Because each component is stored in its own repository, it is easier to make changes to individual components without affecting the other parts of the system.

Additionally, a multi repo approach can make it easier to scale the system, as it is possible to add new repositories for new components as needed, without impacting the existing repositories.

However, one of the main disadvantages of a multi repo approach is that it can add complexity and overhead to the development process. Because each component is stored in its own repository, it can be more difficult to see how the different components fit together, and it can also be more difficult to manage dependencies and ensure that all of the components are using consistent versions of the libraries and other dependencies that they rely on.

In the context of Domain Driven Design (DDD), the choice between a mono repo approach and a multi repo approach can be particularly important. DDD is a software design approach that emphasizes the importance of understanding the domain, or the problem that the software is intended to solve, in order to create a well-designed, maintainable software system. In a mono repo approach, it is easier to see the relationships between the different components of the system, and it is also easier to make changes that affect multiple components at once. This can be particularly useful in a DDD context, as it can help to ensure that the software is well-aligned with the domain and that the different components of the system are working together to solve the problem effectively.

On the other hand, in a multi repo approach, it can be more difficult to see the relationships between the different components, and it can also be more difficult to make changes that affect multiple components at once. This can make it harder to maintain a consistent alignment between the software and the domain, and it can also make it more difficult to ensure that the different components are working together effectively.

Overall, the choice between a mono repo approach and a multi repo approach is a complex one, and it depends on a number of factors, including the size and complexity of the system, the requirements for flexibility and scalability, and the available resources and expertise. Both approaches have their pros and cons, and the best choice will depend on the specific needs of the project.

In the context of Domain Driven Design, the mono repo approach can provide benefits in terms of maintainability and alignment with the domain, but it can also have drawbacks in terms of scalability and manageability. The multi repo approach can provide benefits in terms of granular control and isolation of the different components, but it can also have drawbacks in terms of complexity and overhead. The best approach will depend on the specific needs and goals of the project.