Custom Software Development
Migrating a Legacy Monolith to Microservices
Incrementally decomposed a decade-old .NET monolith into independently deployable services, without a disruptive full rewrite.
01
The Challenge
A single large .NET application had become difficult to deploy safely — every release risked breaking unrelated functionality, and different teams working in the same codebase were frequently blocked on each other.
02
The Approach
1
Identified natural service boundaries using domain-driven design, starting with the least-coupled module as the first extraction.
2
Introduced RabbitMQ as a message bus so extracted services could communicate asynchronously without direct dependencies on the monolith.
3
Used the strangler-fig pattern, routing traffic incrementally to new services via an API gateway while the monolith continued serving the rest.
4
Containerized each new service with Docker and set up independent CI/CD pipelines per service.
03
The Outcome
Two of the highest-risk modules were extracted into independently deployable services, reducing deployment risk in those areas and letting separate teams ship without blocking each other, with the migration pattern documented for continuing the decomposition.
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Ajish
Stephen