What is a distributed monolith and why is it considered bad?

A distributed monolith is an architectural anti-pattern where an application is divided into several services or components that are deployed separately but are tightly coupled and dependent on each other, effectively forming one large monolith.

Why is this bad:

• Deployment and update complexity: changes in one service require changes and restarts of others.
• Low scalability: it is impossible to scale individual parts independently.
• Poor error isolation: a failure in one component can lead to the entire system crashing.
• Support complexity: high coupling complicates understanding and developing the code.

In other words, a distributed monolith does not offer the advantages of microservices but retains their complexities, so it is better to aim for a loosely coupled architecture with clearly defined service boundaries.