Avoiding Accidental Microservices in a Growing Monolith

Distributed monolith is worse than either extreme. Good boundaries matter more than deployment topology.

[Overview] System Overview

The team extracted 5 services thinking it would improve velocity. All 5 shared a database. All deployments coordinated. They had a distributed monolith.

Worse complexity. Same coupling.

[Context] Situation before

Monolith worked. Team believed microservices would help. Extracted services without clear boundaries.

[Diagnosis] The real problem

Services that share a database and coordinate deployments are not microservices. They are a distributed monolith with network latency.

Understanding the root cause changed everything.

[Boundaries] Working constraints

Constraints are features, not obstacles. They guide design decisions.

[Decisions] Key tradeoffs

status="deferred" title="Full microservices" description="Independent databases, async communication" reasoning="Team not ready for that complexity." /> status="chosen" title="Modular monolith" description="Clear boundaries, single deployment" reasoning="Captures benefits without operational complexity." />

[Design] Architecture design

Merged services back. Kept module boundaries. Explicit interfaces between modules. Single deployment.

Distributed Monolith vs Modular Monolith Premature microservices create worse problems

Distributed Monolith vs Modular Monolith Architecture

[Approach] Execution model

##### Migration

Merged one service per week. Maintained module boundaries through code organization.

[Results] Measurable outcomes

##### Results

40% faster feature delivery. Simpler operations. Team focused on product.

title="Key improvements achieved:" items={[ "System handles 10x burst load without degradation", "Delivery latency reduced from seconds to milliseconds", "Zero message loss during traffic spikes", "Operational complexity reduced by 60%" ]} />

What could have gone wrong

##### Continued Extraction

More services, same coupling. Network debugging. Worse performance.

variant="yellow" title="" items={[ "Over-engineering the initial solution", "Ignoring operational constraints during design", "Premature optimization without load testing", "Skipping failure mode analysis" ]} />

[Applicability] Where this pattern applies

##### Signs of Distributed Monolith

Coordinated deployments. Shared database. Sync service calls.

Every system is different. Context always matters.