How to avoid a distributed monolith?

A distributed monolith is an architectural problem where a system is formally divided into services, but they are tightly coupled and dependent on each other, leading to difficulties in scaling and development.

To avoid a distributed monolith, you should:

• Clearly define service boundaries and their responsibilities (single responsibility principle).
• Use asynchronous interactions and events instead of synchronous calls to reduce coupling.
• Avoid direct calls between services, especially if they create dependency cycles.
• Implement contract testing and API versioning for independent development.
• Ensure service autonomy: each service should have its own data store and not depend on the internal implementation of others.

Example: instead of service A directly calling service B to get data, publish change events, and let service B handle them independently.