golang-dependency-injection

Dependency injection in Golang replaces globals and hidden setup with explicit constructor-based wiring, allowing you to test business logic with mocks instead of real databases. You pass dependencies through constructors and compose them cleanly at the application's composition root.

Choosing between google/wire, uber-go/fx, uber-go/dig, and samber/do depends on your project's size, lifecycle requirements, and team needs. Manual constructor injection is recommended for small projects, while larger applications may benefit from code generation or runtime containers.

To refactor tightly coupled Go code, define consumer-defined interfaces and establish shallow dependency graphs. Pass dependencies through constructors instead of using globals, wiring them together explicitly in your main function to ensure loose coupling.

You should limit dependency container usage strictly to the composition root in Go applications. Restricting container access to the entry point prevents container misuse and maintains explicit dependency wiring throughout your service architecture.

Yes, dependency injection frameworks like google/wire and uber-go/fx support lazy initialization. Architecture guidance for Go DI recommends lazy initialization and shallow dependency graphs to manage service lifecycles efficiently.

Dependency injection requires consumer-defined interfaces in Go to ensure loose coupling and testability. By defining interfaces where dependencies are consumed rather than where they are implemented, you can easily inject mocks and isolate business logic for testing.