golang-dependency-injection

Dependency injection in Go is implemented via manual constructor injection or libraries like wire and fx, decoupling constructors from concrete implementations to build testable and loosely coupled services.

Choose between wire, fx, and samber/do by evaluating your project size and lifecycle needs; wire offers compile-time safety, while fx and samber/do provide runtime injection and lifecycle management features.

You do not need a dependency injection library for a small Go application; manual constructor injection is often sufficient, reserving libraries like wire or fx for larger microservices requiring complex wiring.

Defining interfaces at the consumer boundary in Go dependency injection ensures loose coupling and testability, allowing you to mock dependencies easily without exposing unnecessary implementation details.

You should avoid global state in Go dependency injection entirely to maintain testable code, as global variables hide dependencies and make orchestration with libraries like dig or fx unpredictable.