golang-dependency-injection

To implement dependency injection in Go without global state, wire dependencies through constructors at startup. Start with infrastructure, then repositories, then services, then transport, keeping the composition root centralized and avoiding init() for service setup.

Choosing a Go dependency injection library depends on project size and lifecycle needs. Manual constructor injection suits small projects, while libraries like google/wire, uber-go/dig/fx, or samber/do provide automated wiring and lifecycle management for larger, complex applications.

To test dependency injection patterns in Go, use mocks and container cloning to isolate dependencies. Defining interfaces at the consumer boundary ensures components are loosely coupled, allowing reliable unit tests without hitting actual infrastructure or external services.

Defining interfaces at the consumer boundary in Go DI ensures code remains loosely coupled and maintainable. It allows consumers to specify exactly what they need, preventing unnecessary dependencies and making mocking and testing significantly easier.

You need a dependency injection framework like google/wire or uber-go/fx when your Go application scales to a size where manual constructor wiring becomes unmanageable. They automate dependency graph resolution and handle complex lifecycle management.