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Definition of Modular monolith

What is a modular monolith?

A modular monolith, also known as a modular architecture, is a software development approach that combines the simplicity and ease of development of a monolithic architecture with some flexibility and scalability benefits typically associated with microservices architectures.

It breaks down a large application into independent modules, simplifying development, testing, and potentially transitioning to microservices later.

Imagine you have a large toy set, like a LEGO kit, where you can build a big castle. A modular monolith is like building that castle in a way where each room or section is its own little kit. Each part is designed to work well on its own, but it also connects with the other parts to make one big castle.

What is the difference between modular monolithic and microservices?

The distinction between modular monolithic architecture and microservices architecture lies in their approaches to structuring and managing software application components. While both methods tackle the complexities of developing, maintaining, and scaling software systems, they diverge in their strategies.

Modular monolithic architecture organizes an application as a single deployable unit with internally modularized components, simplifying deployment and maintenance. In contrast, microservices architecture divides an application into small, independently deployable services, offering scalability and technological diversity but leading to increased operational complexity.

When to use a modular monolith?

While not a universal solution, modular monoliths excel in certain situations:

  • To mitigate early complexity:

New projects involve learning the domain and ecosystem. Starting with microservices means constant adaptation as understanding evolves, potentially requiring frequent changes to the services themselves. A modular monolith, with fewer moving parts, allows for quicker and easier adjustments as the team's knowledge grows.

  • For simpler operation and management:

A modular monolith packages all modules as a single unit, simplifying development, deployment, and management for the DevOps team.

  • For enhanced stability and performance:

A modular monolith, designed for seamless interaction between modules, often offers better performance and stability than microservices in the early stages of development.

  • For cost-effectiveness

A modular monolith allows deploying all modules on a single server, reducing infrastructure needs and overall costs.

The beauty of modular monoliths is their adaptability. They can be designed in a way that facilitates easier extraction into separate microservices as needed for scaling or transitioning to a distributed architecture. This adaptability allows them to serve as a solid foundation for applications, offering a pathway to microservices that align with evolving business needs and project scope.

Key Takeaways

  • Modular monolith blends the simplicity of monolithic architecture with some flexibility of microservices, breaking down a large application into independent modules.
  • Modular monoliths are single deployable units with internally modularized components, simplifying deployment and maintenance. On the other hand, microservices divide applications into small, independently deployable services, offering scalability but increasing operational complexity.
  • The benefits of this approach are easier development, testing, and potential future transition to microservices.
  • When to Use: modular monoliths are beneficial for new projects to mitigate early complexity, for simpler operation and management, for enhanced stability and performance, and for cost-effectiveness.