Transition from a monolith to microservices in 8 steps

  • 26 Oct 2023

Microservices are buzzing! It might be high time to overhaul your monolithic application around this architecture. While they offer numerous advantages, it's equally important to take into account the challenges and potential issues that can arise with this approach.


So, what exactly are microservices?

Microservices are components, each with its own database and API, that target a specific functionality. Microservices are developed, deployed, and managed independently because they are loosely coupled with the rest of the IT system.


While the term "microservices" has emerged over the past decade, the underlying concepts are far from new:

  • Ensure that each software component does one thing and does it well.
  • Each software component should ultimately become the entry point for another, potentially unidentified, component.
  • Enable rapid testing.

The software industry has long sought ways to break down large monolithic applications into smaller, more modular pieces in order to reduce their complexity (object-oriented programming, service-oriented architecture (SOA), etc.). It's only through the combination of advances in methodology, development, and infrastructure that microservices have emerged as a credible alternative to monolithic applications.


Microservices are not "silver bullets." 

Before decomposing a monolithic service into microservices, it's crucial to assess whether it's genuinely necessary based on the current and future needs of the application.

Here are some cases where it may not be advisable to break down a monolithic service into microservices:

  • If the application has a very limited functional scope, the costs and complexity associated with using microservices may not be justified.
  • If the application's scope is fixed over time and does not encounter scalability issues, there may be no need to divide it into microservices.
  • If the application has complex dependencies that would be challenging to replicate in a microservices architecture.
  • If the cost of decomposing the monolithic application into microservices is high, the investment may not be worthwhile.
  • Finally, it's worth noting that if the application deals with particularly sensitive data, dividing it into microservices can add complexity in terms of security management (but can also bring other benefits – see below).


But they also offer many advantages!

The game can indeed be worth the candle, particularly around the following concepts:

  • Scalability: Decomposing a monolithic service into microservices can enhance scalability by enabling independent scaling of different functional domains.
  • Flexibility: Microservices can improve flexibility by allowing independent development and deployment of different functional domains, making it easier to modify or extend the application.
  • Resilience: Independent management and monitoring of different functional domains can enhance the resilience of the application.
  • Collaboration: If different teams work on different parts of the application, microservices can facilitate their independent work and improve collaboration.
  • Stack: By using microservices, it's possible to employ various technological stacks (programming language, database for each domain of the application), ensuring the use of the most suitable technology for each domain. This can offer numerous benefits, such as improved performance, maintainability, and scalability.
  • Security: Furthermore, decomposing a monolithic service into microservices can enhance security by allowing finer-grained access control and data isolation. With microservices, it's easier to implement security mechanisms like authentication and authorization at the service level, providing finer-grained access control. Moreover, by isolating sensitive data in distinct services, it's possible to limit the exposure of this data and reduce security compromise risks.


8 Steps to Transition to Microservices:

There's no revolutionary method for breaking down a monolithic application into microservices, but a few steps can serve as a guide to kickstart the process.

  • Define the Scope: First, identify distinct functional domains within the monolithic application, such as user management, security management, identity management, etc. The "Domain Driven Design" (DDD) methodology can be helpful for this.
  • Decompose the Application: Divide the monolithic application into smaller, independent services that can be developed, deployed, and scaled autonomously.
  • Define the API Contract: Establish the API contract for each service, which includes data structures and callable methods. This ensures that services can communicate with each other reliably and consistently. Additionally, common code should be separated into modules that can be shared among multiple services.
  • Continuous Integration and Delivery: Implement a robust continuous integration and delivery (CI/CD) pipeline to automate the deployment process and ensure that new services are deployed quickly and reliably.
  • Refactor Code: Review the code of the monolithic application to align it with the new architecture. This may involve transferring code from the monolithic application to the new services and modifying the code to adhere to the new API contract. It may also be necessary to adapt the code to use the new technologies required for microservices.
  • Testing: Once the microservices have been developed and the code has been refactored, test the system to identify errors and performance issues.
  • Monitoring: Microservices require regular monitoring to ensure they are functioning correctly and to detect issues as they arise.
  • Optimization: Finally, optimize the microservices to make them more efficient and performant when necessary. Microservices offer the flexibility to update and enhance individual services without affecting the entire application.


Some Additional Tips

Logging is often an overlooked but crucial aspect of microservices architecture. Since a single call may interact with multiple services before completion, it's essential to pass a common tracking identifier and log it in each service to facilitate tracing and debugging.

Managing transactions can be challenging when multiple services are involved in completing a transaction previously handled by a single application. Therefore, it's crucial to design transaction management from the start, even if it's not immediately required.

Starting small and isolating a small portion of the monolithic service can be beneficial when migrating to microservices. Traffic can be redirected to the new application, and the process can be repeated for other parts of the monolithic service.

Choosing different technologies for each service can be an interesting idea to stay at the cutting edge. However, it's important to consider the technical skills and learning curve of the team.


I Want to Get Started!

Our message is clear: taking some time to carefully consider before diving into microservices can prevent long-term issues. Good planning and thoughtful design are essential to ensure the success of the transition to a microservices-based architecture.

If your team lacks expertise in distributed systems, microservices, and containerization, that's not a problem! Ours have it. Reach out to our experts on the subject!