Golang Samber Do
Samuel BertheCommunityCreated by samberDistributed by Samuel Berthe
- Skill
- Tool integration
- Software development
- MIT
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AutoGineer summary
Written by AutoGineer from the skill’s own files, not by the author
This skill provides guidance on using samber/do, a generics-based dependency injection toolkit for Go 1.18+. It covers service registration, lifecycle management, scoping, and integration patterns to help developers move away from manual constructor injection. The skill emphasizes maintaining a clean composition root, using interfaces for decoupling, and leveraging the library's built-in support for health checks and graceful shutdowns.
What it does
- Registers services using lazy, eager, transient, or value-based providers.
- Organizes service registration into modular packages.
- Manages service lifecycles with health checks and graceful shutdown hooks.
- Supports hierarchical dependency scoping for better isolation.
- Provides utilities for struct-based injection using tags.
- Facilitates testing through container cloning and service overrides.
When to use it
- When adopting the samber/do library for dependency injection in a Go project.
- When refactoring manual constructor injection to reduce boilerplate.
- When you need to manage complex service lifecycles and dependencies in a type-safe manner.
- When organizing large Go applications into distinct, testable modules.
Advantages
- Type-safe dependency resolution using Go generics.
- Reduces manual wiring boilerplate in complex applications.
- Built-in support for graceful shutdowns and health monitoring.
- Easy to test via container cloning and mock overrides.
- Supports modular architecture through package-level registration.
Usage examples
- “How do I register a database service in samber/do?”
- You use do.Provide to register a provider function that returns the service, which will be lazily instantiated when first requested.
- “How can I mock a dependency for testing with samber/do?”
- You can clone the existing injector using injector.Clone() and then use do.OverrideValue to replace the production service with your mock.
- “What is the best way to handle service dependencies inside a provider?”
- Use do.MustInvoke[T](i) inside your provider function; the library will automatically recover any panics and convert them into errors at the composition root.
- “How do I organize my services into modules?”
- Use do.Package() to group related service registrations and pass these packages to the do.New() constructor in your main function.
Install
Download the skill as a ZIP:
https://mp-staging.autogineer.com/agent-skills/samber/golang-samber-do/downloadUnzip it into the cross-client skills folder of your project:
mkdir -p .agents/skills && unzip golang-samber-do.zip -d .agents/skills
Documentation by samber
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:
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-devskill (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-goplsskill (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:
go get -u github.com/samber/do/v2Core Concepts
The Injector (Container)
import "github.com/samber/do/v2"
injector := do.New()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:
type Provider[T any] func(i Injector) (T, error)Basic Usage
1. Define and Register Services
Follow "Accept Interfaces, Return Structs":
// Register a service (lazy by default)
do.Provide(injector, func(i do.Injector) (Database, error) {
return &PostgreSQLDatabase{connString: "postgres://..."}, nil
})
// Register a pre-created value
do.ProvideValue(injector, &Config{Port: 8080})
// Register a transient service (new instance each time)
do.ProvideTransient(injector, func(i do.Injector) (*Logger, error) {
return &Logger{}, nil
})
// Register an eager service (created immediately at startup)
do.ProvideValue(injector, &Config{Port: 8080})2. Invoke Services
The container MUST only be accessed at the composition root:
// Invoke with error handling — reserve for call sites outside the DI graph
// (e.g. an HTTP handler that must degrade gracefully instead of crashing)
db, err := do.Invoke[Database](injector)
// MustInvoke panics on error — preferred in providers, recovered by do.Invoke on the parent call
db := do.MustInvoke[Database](injector)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 withdo.Invokecosts an extraif err != nil { return nil, err }on every call.do.MustInvokepanics instead, but samber/do correctly catches and recovers that panic at the enclosingInvokecall and converts it back into a regular error — this recover happens inside the library itself, not in caller code, soMustInvokeis 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
func NewUserService(i do.Injector) (UserService, error) {
db := do.MustInvoke[Database](i)
cache := do.MustInvoke[Cache](i)
return &userService{db: db, cache: cache}, nil
}
do.Provide(injector, NewUserService)4. Implicit Aliasing (Preferred)
Register a concrete type and invoke as an interface without explicit aliasing:
// Register concrete type
do.Provide(injector, func(i do.Injector) (*PostgreSQLDatabase, error) {
return &PostgreSQLDatabase{}, nil
})
// Invoke directly as interface (implicit aliasing)
db := do.MustInvokeAs[Database](injector)5. Named Services
Register multiple services of the same type:
do.ProvideNamed(injector, "primary-db", func(i do.Injector) (*Database, error) {
return &Database{URL: "postgres://primary..."}, nil
})
mainDB := do.MustInvokeNamed[*Database](injector, "primary-db")Package Organization
Use do.Package() to organize service registration by module:
// infrastructure/package.go
var Package = do.Package(
do.Lazy(func(i do.Injector) (*postgres.DB, error) {
cfg := do.MustInvoke[*Config](i)
return postgres.Connect(cfg.DatabaseURL)
}),
do.Lazy(func(i do.Injector) (*redis.Client, error) {
cfg := do.MustInvoke[*Config](i)
return redis.NewClient(cfg.RedisURL), nil
}),
)
// main.go
injector := do.New(infrastructure.Package, service.Package)Full Application Setup
func main() {
injector := do.New(
infrastructure.Package,
repository.Package,
service.Package,
transport.Package,
)
server := do.MustInvoke[*http.Server](injector)
go server.ListenAndServe()
_ = injector.ShutdownOnSignalsWithContext(context.Background(), os.Interrupt)
}Best Practices
Depend on interfaces, not concrete types — lets you swap implementations in tests without touching production code
Each service should have one job — services with multiple responsibilities are harder to test and harder to replace
Keep dependency trees shallow — chains beyond 3-4 levels make initialization order fragile and errors harder to trace
Handle errors in provider functions — a silently failing provider creates a broken service that crashes later in unexpected places
Use scopes to organize services by lifecycle — request-scoped services prevent leaks, global services prevent redundant initialization
Use
do.MustInvoke*inside provider functions instead ofdo.Invoke*— samber/do correctly catches and recovers the panic at the outerInvokecall, 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.
For testing patterns (cloning, overrides, mocks), see Testing.
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-injectionskill for DI concepts, comparison, and when to adopt a DI library→ See
samber/cc-skills-golang@golang-structs-interfacesskill for interface design patterns→ See
samber/cc-skills-golang@golang-testingskill for general testing patterns
Files
- ATTRIBUTION.mdAdded by AutoGineer905 B
- LICENSELicence file added by AutoGineer1.0 KiB
- SKILL.md9.1 KiB
- evals/evals.json11.6 KiB
- references/advanced.md5.7 KiB
- references/testing.md1.4 KiB
evals/evals.json
[
{
"id": 1,
"name": "v2-import-not-v1",
"description": "Tests whether the model uses samber/do/v2, never v1",
"prompt": "I want to set up dependency injection in my Go project using samber/do. Show me how to install it and create a basic container.",
"trap": "Without the skill, the model might import github.com/samber/do (v1) instead of github.com/samber/do/v2",
"assertions": [
{"id": "1.1", "text": "Uses go get github.com/samber/do/v2 (not github.com/samber/do without v2)"},
{"id": "1.2", "text": "Import path is github.com/samber/do/v2 in the code"},
{"id": "1.3", "text": "Uses do.New() to create the container"},
{"id": "1.4", "text": "Does NOT reference v1 API or import paths anywhere"}
]
},
{
"id": 2,
"name": "lazy-vs-eager-vs-transient",
"description": "Tests whether the model correctly chooses between lazy, eager, and transient service types",
"prompt": "I have three services in my Go app: (1) a database connection that must be ready before serving requests, (2) a user repository that's only needed when user endpoints are called, and (3) a request logger that should be a fresh instance per request. Register them with samber/do.",
"trap": "Without the skill, the model registers all three with do.Provide (lazy), missing do.Eager for the database and do.ProvideTransient for the logger",
"assertions": [
{"id": "2.1", "text": "Uses do.Provide with do.Eager wrapper (or equivalent) for the database connection that must be ready immediately"},
{"id": "2.2", "text": "Uses do.Provide (lazy, the default) for the user repository that's only needed on demand"},
{"id": "2.3", "text": "Uses do.ProvideTransient for the request logger that needs a fresh instance each time"},
{"id": "2.4", "text": "Correctly distinguishes between the three service lifecycle types"},
{"id": "2.5", "text": "Does NOT register all three services with the same registration function"}
]
},
{
"id": 3,
"name": "implicit-aliasing-invokeAs",
"description": "Tests whether the model uses InvokeAs for implicit aliasing instead of explicit aliasing",
"prompt": "I have a PostgreSQLDatabase struct that implements a Database interface. I want to register the concrete type but invoke it as the interface in my Go service. How do I set this up with samber/do?",
"trap": "Without the skill, the model uses do.As or do.MustAs for explicit aliasing, which is only needed for legacy code. Implicit aliasing via InvokeAs is preferred.",
"assertions": [
{"id": "3.1", "text": "Registers the concrete type *PostgreSQLDatabase with do.Provide"},
{"id": "3.2", "text": "Uses do.MustInvokeAs[Database] or do.InvokeAs[Database] to invoke as the interface"},
{"id": "3.3", "text": "Prefers implicit aliasing (InvokeAs) over explicit aliasing (As/MustAs)"},
{"id": "3.4", "text": "Does NOT require a separate alias registration step for this basic case"},
{"id": "3.5", "text": "The provider function returns the concrete type, not the interface"}
]
},
{
"id": 4,
"name": "package-organization",
"description": "Tests whether the model organizes service registrations using do.Package",
"prompt": "My Go project has infrastructure services (database, cache), domain services (user service, order service), and transport services (HTTP handlers). How should I organize the DI registrations with samber/do?",
"trap": "Without the skill, the model registers everything in main.go in a long list, missing do.Package for modular organization",
"assertions": [
{"id": "4.1", "text": "Uses do.Package to group related service registrations into separate packages/modules"},
{"id": "4.2", "text": "Creates separate package variables (e.g., infrastructure.Package, service.Package, transport.Package)"},
{"id": "4.3", "text": "Passes all packages to do.New() in main.go: do.New(infrastructure.Package, service.Package, transport.Package)"},
{"id": "4.4", "text": "Each package groups related services (infra, domain, transport) rather than one giant registration list"},
{"id": "4.5", "text": "Uses do.Lazy wrapper inside do.Package for lazy service registration"}
]
},
{
"id": 5,
"name": "scopes-for-lifecycle",
"description": "Tests whether the model uses scopes to organize services by lifecycle and visibility",
"prompt": "In my Go web app using samber/do, I have global services (config, logger) and per-request services (request context, current user). How do I prevent per-request services from being shared across requests?",
"trap": "Without the skill, the model registers everything in the root container, leading to shared per-request state across concurrent requests",
"assertions": [
{"id": "5.1", "text": "Uses do.Scope to create child scopes for per-request services"},
{"id": "5.2", "text": "Registers global/stateless services (config, logger) in the root container"},
{"id": "5.3", "text": "Creates a new scope per request for request-scoped services"},
{"id": "5.4", "text": "Child scope services can access parent (root) services"},
{"id": "5.5", "text": "Does NOT register request-scoped services in the root container"}
]
},
{
"id": 6,
"name": "testing-clone-override",
"description": "Tests whether the model uses container cloning and overrides for testing",
"prompt": "I have a Go service registered in samber/do that depends on a Database interface. I want to test the service with a mock database. How do I set up the test?",
"trap": "Without the skill, the model creates a brand new container from scratch in tests, missing the Clone+Override pattern that reuses the production container configuration",
"assertions": [
{"id": "6.1", "text": "Uses injector.Clone() or do.Clone() to clone the production container"},
{"id": "6.2", "text": "Uses do.Override or do.OverrideValue to replace the Database with a mock"},
{"id": "6.3", "text": "Invokes the service under test from the cloned container"},
{"id": "6.4", "text": "Does NOT build a completely new container from scratch for each test (unless justified)"},
{"id": "6.5", "text": "The test is isolated — changes to the cloned container don't affect the original"}
]
},
{
"id": 7,
"name": "health-check-interface",
"description": "Tests whether the model implements the Healthchecker interface for service health checks",
"prompt": "I have a database service registered in samber/do. I want to add health checking so I can verify the database is reachable. How do I implement this?",
"trap": "Without the skill, the model writes a standalone health check function instead of implementing the Healthchecker interface that integrates with do's lifecycle",
"assertions": [
{"id": "7.1", "text": "Implements a HealthCheck() method on the database service struct"},
{"id": "7.2", "text": "The HealthCheck method signature is either HealthCheck() error or HealthCheck(ctx context.Context) error"},
{"id": "7.3", "text": "Uses do.HealthCheck[Database](injector) to invoke the health check through the container"},
{"id": "7.4", "text": "Does NOT write a standalone function that manually fetches the service and pings it"},
{"id": "7.5", "text": "The health check actually tests connectivity (e.g., conn.Ping())"}
]
},
{
"id": 8,
"name": "graceful-shutdown-interface",
"description": "Tests whether the model implements the Shutdowner interface for graceful shutdown",
"prompt": "My Go application uses samber/do for DI. I need to gracefully shut down all services (close database connections, flush logs) when the application receives SIGINT. Show me how.",
"trap": "Without the skill, the model writes manual shutdown code with signal handling, missing do's ShutdownOnSignals integration and Shutdowner interface",
"assertions": [
{"id": "8.1", "text": "Implements Shutdown() or Shutdown(ctx context.Context) method on services that need cleanup"},
{"id": "8.2", "text": "Uses injector.ShutdownOnSignals or injector.ShutdownOnSignalsWithContext for signal-based shutdown"},
{"id": "8.3", "text": "Passes os.Interrupt or syscall.SIGTERM to the shutdown function"},
{"id": "8.4", "text": "Does NOT manually implement signal handling and iterate over services to shut them down"},
{"id": "8.5", "text": "May use context.WithTimeout for shutdown deadline"}
]
},
{
"id": 9,
"name": "composition-root-only",
"description": "Tests that the container is only accessed at the composition root, not passed around or used as a service locator",
"prompt": "I'm using samber/do for DI in my Go project. I have a UserHandler that needs a UserService. Should I pass the do.Injector to UserHandler so it can resolve its own dependencies?",
"trap": "Without the skill, the model passes the injector into business logic code, turning it into an anti-pattern service locator",
"assertions": [
{"id": "9.1", "text": "Advises against passing do.Injector into business logic or handler code"},
{"id": "9.2", "text": "States that the container should only be accessed at the composition root (main/startup)"},
{"id": "9.3", "text": "Shows resolving dependencies in the provider function using do.MustInvoke from the injector parameter"},
{"id": "9.4", "text": "The UserHandler receives its dependencies as constructor parameters, not the container"},
{"id": "9.5", "text": "Explains that passing the container creates a service locator anti-pattern that hides dependencies"}
]
},
{
"id": 10,
"name": "named-services-same-type",
"description": "Tests whether the model uses named services when registering multiple instances of the same type",
"prompt": "My Go app connects to two PostgreSQL databases — a primary for writes and a replica for reads. Both are *sql.DB instances. How do I register and retrieve them with samber/do?",
"trap": "Without the skill, the model tries to register both with do.Provide which overwrites the first registration, or wraps them in different types unnecessarily",
"assertions": [
{"id": "10.1", "text": "Uses do.ProvideNamed to register each database with a distinct name (e.g., 'primary-db', 'replica-db')"},
{"id": "10.2", "text": "Uses do.MustInvokeNamed or do.InvokeNamed to retrieve each database by name"},
{"id": "10.3", "text": "Both databases are registered as the same type (*sql.DB or a Database interface)"},
{"id": "10.4", "text": "Does NOT create unnecessary wrapper types just to distinguish the two databases"},
{"id": "10.5", "text": "Does NOT overwrite the first registration by using do.Provide twice for the same type"}
]
},
{
"id": 11,
"name": "struct-injection-with-tags",
"description": "Tests knowledge of struct injection using do tags",
"prompt": "I have a Go struct with multiple service dependencies that I want to inject from my samber/do container. Is there a way to avoid calling MustInvoke for each field manually?",
"trap": "Without the skill, the model manually invokes each dependency and assigns to struct fields, missing the do:\"\" tag-based struct injection",
"assertions": [
{"id": "11.1", "text": "Uses struct field tags with do:\"\" or do:\"service-name\" syntax"},
{"id": "11.2", "text": "Uses do.MustInvokeStruct or do.InvokeStruct to populate the struct"},
{"id": "11.3", "text": "Shows that do:\"\" uses the type for resolution and do:\"name\" uses a named service"},
{"id": "11.4", "text": "Does NOT manually call MustInvoke for each field when struct injection is available"}
]
}
]
Requirements and compatibility
Written for: Claude Code, OpenAI Codex
Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta
“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.
Needs: Declares allowed tools, Claude Code frontmatter
The author says: Designed for Claude Code, Codex or similar harness, and for projects using Golang.
Security
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Attribution and licence
- Created by
- samber
- Publisher
- Samuel Berthe (Community)
- Distributed by
- Samuel Berthe
- Source
- samber/cc-skills-golang · skills/golang-samber-do · commit bb1d43d
- Licence
- MIT License (redistribution allowed)
- LICENSE (added by AutoGineer from LICENSE)
- ATTRIBUTION.md (written by AutoGineer)
- Synced
AutoGineer is not affiliated with or endorsed by samber or Samuel Berthe.
Download ZIP
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