Microservices: Lessons From the Trenches

I've been designing and building microservices architectures for years across healthcare eligibility platforms, financial systems, and EDI processing pipelines. Here's what I've actually learned — as opposed to what the blog posts and conference talks would have you believe.

Service Boundaries Are Everything

The most important decision in a microservices architecture isn't your tech stack, your deployment strategy, or your service mesh. It's where you draw the boundaries between services.

Get this wrong and you'll spend the next two years dealing with services that are too chatty, data that's duplicated inconsistently, and deployments that require coordinating six teams.

My approach: align service boundaries with business capabilities, not technical layers. Don't create a "database service" and an "API service." Create an "eligibility service" and a "claims service." Each service owns its domain, its data, and its behavior.

Domain-Driven Design's bounded contexts map beautifully to microservice boundaries. If you're not using DDD to inform your service design, you're guessing.

The Network Is Not Reliable

This sounds obvious. It's not obvious enough.

In a monolith, a function call either succeeds or throws an exception. In a microservices architecture, a service call can succeed, fail, time out, succeed but return stale data, fail on the way back after succeeding on the server, or succeed on the second retry after failing on the first — which means it ran twice.

Every inter-service communication needs to account for:

Timeouts. Set them explicitly. A missing timeout is a cascading failure waiting to happen.
Retries with backoff. Not all failures are permanent. Retry with exponential backoff for transient failures.
Circuit breakers. If a service is consistently failing, stop calling it. Let it recover.
Idempotency. Any operation that can be retried must produce the same result regardless of how many times it's called.

Data Consistency Is Your Biggest Challenge

Microservices means distributed data. Distributed data means you can't have transactions that span services. This is the single biggest source of bugs and confusion I've seen in microservices architectures.

The solution is eventual consistency with explicit compensation:

Each service is the source of truth for its own data.
Changes propagate through events (see: event-driven architecture).
When something goes wrong, you compensate rather than rollback.

This requires a mindset shift. Your system will have moments where different services have slightly different views of the world. Design for that, don't fight it.

Don't Start With Microservices

Controversial, but I'll say it: most projects shouldn't start with microservices. Start with a well-structured monolith with clear module boundaries. When specific parts need to scale independently, extract them into services.

I've seen too many teams adopt microservices on day one because it's the "modern" approach, then spend months dealing with distributed systems complexity when a monolith would have been perfectly adequate.

Microservices solve specific problems: independent scaling, independent deployment, team autonomy at scale. If you don't have those problems yet, you don't need microservices yet.

Observability Is Non-Negotiable

In a monolith, you can step through code with a debugger. In microservices, a single request might touch ten services. Without proper observability, debugging is impossible.

The minimum:

Distributed tracing with correlation IDs across every service
Centralized logging with structured, searchable logs
Health checks and metrics for every service
Alerting on error rates, latency percentiles, and queue depths

Invest in this infrastructure before you go to production. Not after.

The Honest Assessment

Microservices are a powerful architectural pattern for the right problems at the right scale. They are not a universal best practice. The organizations that succeed with them are the ones that adopt them for clear, specific reasons — not because they read a blog post about how Netflix does it.