Service-Architecture is deliberate Technical Debt (And that’s its strength)

At my first job over a decade ago, I watched a team grapple with a monolith that had grown unwieldy. Rather than attempting an ambitious rewrite or adding another quick fix, we carefully analysed our options. Ultimately, we chose to transition incrementally to a service-oriented architecture.

At first glance, moving from a monolith to services might look like deliberately taking on technical debt, and that's precisely what it is: debt, a valuable software development tool that we can strategically invest in as long as we carefully monitor its interest. This strategic approach not only helps teams navigate out of monolithic systems but also provides invaluable opportunities for team growth and clarity.

However, it's essential to acknowledge that a monolith becoming problematic often signals an underlying skill gap rather than inherent flaws in the architecture itself. Engineers might not always readily admit it, but messy monoliths usually reflect unclear domain boundaries or gaps in understanding domain-driven design principles. This is precisely why transitioning to services can be especially valuable. It provides the opportunity for training and developing these critical skills.

Here's why migrating to services can be a pragmatic, productive choice:

1. Manageable Transitions

Monolithic applications can become difficult to modify because even small changes might cause widespread issues. By incrementally extracting clearly defined domains into services, such as user authentication, payment processing, or notification systems, you manage complexity effectively. Yes, this adds overhead in the form of new service boundaries, but the cost is predictable and worthwhile, enabling continuous progress without halting operations.

2. Practical Skill Development

Transitioning to services isn't just a structural decision; it's also a practical training opportunity. Teams inexperienced with clear domain boundaries and modern software practices benefit immensely. Experienced developers can focus on higher-level system design, integration complexities, abstraction layers, and infrastructure. At the same time, newer team members are free to learn, experiment, and grow within clearly defined and isolated service boundaries, greatly reducing risk to the overall system stability.

3. Increased Visibility into Technical Debt

Within a monolith, technical debt can be hidden or easily overlooked. When services are extracted, problematic areas become more obvious. Hacky logic, inefficient queries, and legacy shortcuts become clearly visible, making them easier to prioritize for improvement. While this initially introduces new maintenance tasks, the resulting transparency makes managing and reducing technical debt more effective.

4. Clear Ownership and Faster Iteration

A monolithic codebase might bottleneck productivity due to merge conflicts, complex dependencies, and centralized decision-making. Services alleviate these issues by establishing clear ownership over specific domains, such as billing or search. Teams gain autonomy, accelerating development, improving morale, and enabling faster iteration cycles. This clarity and autonomy outweigh the minor overhead associated with coordinating between services.

5. Gradual Evolution, Not Revolution

Adopting services doesn't require immediately retiring the monolith. The "strangler" approach, gradually migrating functionalities to services, lets the legacy system continue running while methodically untangling its complexity. This prevents disruptive rewrites, keeps your application stable, and helps avoid risky, large-scale migrations.

Avoiding the Pitfalls of Microservices

One common critique of service architectures is the complexity associated with microservices. Issues like excessive interservice communication, complicated deployments, and infrastructure overhead often arise when services are too granular. However, these challenges are significantly mitigated by adhering to larger, clearly defined, domain-based services. By grouping related functionality into more substantial services, teams maintain clear communication boundaries, simplify deployments, and reduce the complexity typically associated with microservices.

Returning to the Monolith with Improved Skills

It's crucial to note that while services can facilitate a smoother transition away from problematic monoliths, a monolith built with clear, domain-based architecture remains an ideal target state for many applications. Once teams master domain boundaries through service-based transitions, it's entirely possible and sometimes preferable to merge these well-defined services back into a cohesive monolithic structure. With newly acquired skills and clearly delineated boundaries, teams can avoid the pitfalls of their original monolith, benefiting from both simplicity and clarity.

The Strategic Value of Technical Debt

The move to services indeed creates technical debt, but it's debt you manage intentionally and strategically. By embracing this controlled form of complexity, teams gain clarity, autonomy, and skill-development opportunities. Experienced engineers guide the transition, newer team members rapidly upskill, and the monolith steadily improves without major disruption.

When someone critiques the additional complexity of service architectures, acknowledge it openly. It's a deliberate investment. It's precisely this intentional, controlled debt that enables steady, sustainable progress toward a maintainable and scalable system.

Next time you face an intimidating monolith, consider this strategic approach. Extract services thoughtfully, provide clear boundaries, and empower your teams. Ultimately, you might even merge back into a stronger, clearer, and more maintainable monolith skillfully designed and efficiently managed.