Dependency injection in Golang using samber/do — service containers, lifecycle management, scopes, health checks, graceful shutdown, and module organization. Apply when using or adopting samber/do, when the codebase imports github.com/samber/do or github.com/samber/do/v2, or when refactoring manual

Persona: You are a Go architect setting up dependency injection. You keep the container at the composition root, depend on interfaces not concrete types, and treat provider errors as first class failures. Using samber/do for Dependency Injection in Go Type safe dependency injection toolkit for Go based on Go 1.18+ generics. Official Resources: [pkg.go.dev/github.com/samber/do/v2](https://pkg.go.dev/github.com/samber/do/v2) [do.samber.dev](https://do.samber.dev) [github.com/samber/do/v2](https://github.com/samber/do) This skill is not exhaustive — refer to library documentation and code examples for more information: For Go package docs, symbols, versions, importers, and known vulnerabilities, → See samber/cc skills golang@golang pkg go dev skill ( godig ), preferred over Context7 for Go package facts. To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See samber/cc skills golang@golang gopls skill ( gopls ). Context7 remains a fallback for docs not indexed on pkg.go.dev. Install v2 — v1 is superseded and lacks the generics based container, scopes, and lifecycle hooks documented below, so v1 era guidance misleads on every API in this skill: Core Concepts The Injector (Container) Service Types Lazy (default): Created when first requested Eager : Created immediately when the container starts Transient : New instance created on every request Value : Pre created value, no instantiation Provider Functions Services MUST be registered via provider functions: Basic Usage 1. Define and Register Services Follow "Accept Interfaces, Return Structs": 2. Invoke Services The container MUST only be accessed at the composition root: Inside a provider function, always use do.MustInvoke (or MustInvokeAs / MustInvokeNamed / MustInvokeStruct ) rather than the error returning variant: A provider already returns (T, error) , so propagating a dependency failure with do.Invoke costs an extra if err != nil { return nil, err } on every call. do.MustInvoke panics instead, but samber/do correctly catches and recovers that panic at the enclosing Invoke call and converts it back into a regular error — this recover happens inside the library itself, not in caller code, so MustInvoke is safe to use inside providers. The failure still surfaces as an error at the composition root, just without the manual boilerplate in every provider. 3. Service Dependencies 4. Implicit Aliasing (Preferred) Register a concrete type and invoke as an interface without explicit aliasing: 5. Named Services Register multiple services of the same type: Package Organization Use do.Package() to organize service registration by module: Full Application Setup Best Practices 1. Depend on interfaces, not concrete types — lets you swap implementations in tests without touching production code 2. Each service should have one job — services with multiple responsibilities are harder to test and harder to replace 3. Keep dependency trees shallow — chains beyond 3 4 levels make initialization order fragile and errors harder to trace 4. Handle errors in provider functions — a silently failing provider creates a broken service that crashes later in unexpected places 5. Use scopes to organize services by lifecycle — request scoped services prevent leaks, global services prevent redundant initialization 6. Use do.MustInvoke inside provider functions instead of do.Invoke — samber/do correctly catches and recovers the panic at the outer Invoke call, turning it back into a returned error, so it's safe to use inside providers and you get the same error propagation without the boilerplate For scopes, lifecycle management, struct injection, and debugging, see [Advanced Usage](./references/advanced.md). For testing patterns (cloning, overrides, mocks), see [Testing](./references/testing.md). Quick Reference Registration Function Purpose do.Provide[T]() Register lazy service (default) do.ProvideNamed[T]() Register named lazy service do.ProvideValue[T]() Register pre created value do.ProvideNamedValue[T]() Register named value do.ProvideTransient[T]() Register new instance each time do.ProvideNamedTransient[T]() Register named transient service do.Package() Group service registrations Invocation Function Purpose do.Invoke[T]() Get service (with error) do.InvokeNamed[T]() Get named service do.InvokeAs[T]() Get first service matching interface do.InvokeStruct[T]() Inject into struct fields using tags do.MustInvoke[T]() Get service (panic on error) do.MustInvokeNamed[T]() Get named service (panic on error) do.MustInvokeAs[T]() Get service by interface (panic on error) do.MustInvokeStruct[T]() Inject into struct (panic on error) Cross References → See samber/cc skills golang@golang dependency injection skill for DI concepts, comparison, and when to adopt a DI library → See samber/cc skills golang@golang structs interfaces skill for interface design patterns → See samber/cc skills golang@golang testing skill for general testing patterns

golang-samber-do