Should we always break a monolith into microservices?

No. Most teams get faster by enforcing module boundaries and shipping a modular monolith first. Extract services only where the domain seam is clear and the change rate/business risk makes the distributed-systems tax worth it.

How do we split a shared database without breaking everything?

Start with explicit write ownership and stop cross-domain writes. Use an outbox pattern for reliable event publication and make consumers idempotent. Full DB-per-service can come later, but you can get major wins without it.

What metrics should we track to prove modernization is working?

Deploy frequency, lead time for changes, change-failure rate, MTTR, plus service SLOs (latency/error rate) and unit costs (e.g., cost per 1k requests or per customer workflow).

Case-studies · Dec 24, 2025 · 8 minute read

The Monolith That Wouldn’t Die: How We Made a 12-Year Legacy App Ship Weekly Without a “Big Rewrite”

A real-world modernization: modularizing a Java/Spring monolith, carving out the right services, and turning “deploy day” from a fire drill into a routine.

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The Monolith That Wouldn’t Die: How We Made a 12-Year Legacy App Ship Weekly Without a “Big Rewrite”

Key takeaways

Implementation checklist