dix

dix is a lightweight yet powerful dependency injection framework for Go.

Inspired by uber-go/dig, with support for advanced dependency management and namespace isolation.

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Table of Contents

• When to use dix
• Features
• Installation
• Quick Start
• Core API
• Injection Patterns
• Modules
• Diagnostics
• Development
• Examples
• Documentation

When to use dix

• You need runtime dependency registration (plugins, dynamic modules, conditional wiring).
• You want built-in diagnostics: structured trace logs, JSONL export, and an HTTP dependency graph.
• You prefer a dig-like API with safe Try* variants, map/list grouping, and method injection.

For compile-time wiring with minimal runtime overhead, see google/wire. For Uber's fx ecosystem, see uber-go/dig.

✨ Features

Feature	Description
🔄 Cycle Detection	Auto-detect dependency cycles
📦 Multiple Injection	Support func, struct, map, list
🏷️ Namespace	Dependency isolation via map key
🎯 Multi-Output	Struct can provide multiple dependencies
🪆 Nested Support	Support nested struct injection
🔧 Non-Invasive	Zero intrusion to original objects
🛡️ Safe API	TryProvide/TryInject won't panic
🌐 Visualization	HTTP module for dependency graph

📦 Installation

go get github.com/pubgo/dix/v2

🚀 Quick Start

package main

import (
    "fmt"
    "github.com/pubgo/dix/v2"
)

type Config struct {
    DSN string
}

type Database struct {
    Config *Config
}

type UserService struct {
    DB *Database
}

func main() {
    // Create container
    di := dix.New()

    // Register Providers
    dix.Provide(di, func() *Config {
        return &Config{DSN: "postgres://localhost/mydb"}
    })

    dix.Provide(di, func(c *Config) *Database {
        return &Database{Config: c}
    })

    dix.Provide(di, func(db *Database) *UserService {
        return &UserService{DB: db}
    })

    // Inject and use
    dix.Inject(di, func(svc *UserService) {
        fmt.Println("DSN:", svc.DB.Config.DSN)
    })
}

For production startup, prefer TryProvide / TryInject to avoid panics and keep the process alive for diagnostics:

if err := dix.TryProvide(di, NewDatabase); err != nil {
    log.Fatal(err)
}
if err := dix.TryInject(di, Run); err != nil {
    log.Fatal(err)
}

📖 Core API

API	Panics on error	Description
New(...Option)	—	Create a container
Provide(di, fn)	yes	Register a provider
TryProvide(di, fn)	no	Register a provider, returns error
Inject(di, target)	yes	Inject into a function or struct
TryInject(di, target)	no	Inject, returns error
InjectT[T](di)	yes	Allocate a struct and inject exported fields
InjectTContext[T](ctx, di)	yes	Allocate a struct and inject with trace context
InjectContext / TryInjectContext	yes / no	Inject with trace context propagation
Version()	—	Return embedded version string

Container options:

Option	Default	Description
WithValuesNull()	enabled	Tolerate missing map/list dependencies (resolve as empty collections)
WithRejectEmptyCollections()	disabled	Reject missing map/list dependencies instead of resolving them as empty collections
WithProviderTimeout(d)	15s	Per-provider execution timeout (0 = disabled)
WithSlowProviderThreshold(d)	2s	Warn when provider is slow (0 = disabled)
WithTraceBuffer(n)	off	Give the container a private in-memory trace buffer of n events (isolated from the global sink)

Provide / TryProvide

Register constructor (Provider) to container:

// Standard version - panics on error
dix.Provide(di, func() *Service { return &Service{} })

// Safe version - returns error
err := dix.TryProvide(di, func() *Service { return &Service{} })
if err != nil {
    log.Printf("Registration failed: %v", err)
}

Inject / TryInject

Inject dependencies from container:

// Function injection
dix.Inject(di, func(svc *Service) {
    svc.DoSomething()
})

// Struct injection
type App struct {
    Service *Service
    Config  *Config
}
app := &App{}
dix.Inject(di, app)

// Safe version
err := dix.TryInject(di, func(svc *Service) {
    // ...
})

Generic Helpers

// Inject into a new struct value
app := dix.InjectT[App](di)

// Inject with request-scoped trace context
err := dix.TryInjectContext(ctx, di, func(svc *Service) {
    svc.DoSomething()
})

Thread Safety

Dix containers are not thread-safe. Do not call Provide / Inject (or their Try* variants) concurrently on the same container instance.

Recommended usage:

• Register all providers during application startup (single goroutine).
• After startup, only read resolved dependencies, or continue injection from a single goroutine.
• Use separate Dix instances per goroutine if you need isolated containers.
• For a process-wide singleton, prefer dixglobal only when startup is single-threaded.

Startup Options

di := dix.New(
    dix.WithProviderTimeout(2*time.Second),              // default: 15s; 0 disables
    dix.WithSlowProviderThreshold(300*time.Millisecond), // default: 2s; 0 disables
)

🎯 Injection Patterns

Struct Injection

type In struct {
    Config   *Config
    Database *Database
}

type Out struct {
    UserSvc  *UserService
    OrderSvc *OrderService
}

// Multiple inputs and outputs
dix.Provide(di, func(in In) Out {
    return Out{
        UserSvc:  &UserService{DB: in.Database},
        OrderSvc: &OrderService{DB: in.Database},
    }
})

Map Injection (Namespace)

// Provide with namespace
dix.Provide(di, func() map[string]*Database {
    return map[string]*Database{
        "master": &Database{DSN: "master-dsn"},
        "slave":  &Database{DSN: "slave-dsn"},
    }
})

// Inject specific namespace
dix.Inject(di, func(dbs map[string]*Database) {
    master := dbs["master"]
    slave := dbs["slave"]
})

List Injection

// Provide same type multiple times
dix.Provide(di, func() []Handler {
    return []Handler{&AuthHandler{}}
})
dix.Provide(di, func() []Handler {
    return []Handler{&LogHandler{}}
})

// Inject all
dix.Inject(di, func(handlers []Handler) {
    // handlers contains AuthHandler and LogHandler
})

🧩 Modules

dixglobal - Global Container

Provides global singleton container for simple applications:

import "github.com/pubgo/dix/v2/dixglobal"

// Use directly without creating container
dixglobal.Provide(func() *Config { return &Config{} })
dixglobal.Inject(func(c *Config) { /* ... */ })

dixcontext - Context Integration

Bind container to context.Context:

import "github.com/pubgo/dix/v2/dixcontext"

// Store in context
ctx := dixcontext.Create(context.Background(), di)

// Retrieve and use
container := dixcontext.Get(ctx)

// Non-panicking lookup
container = dixcontext.GetOrNil(ctx)

dixhttp - Dependency Visualization

Web interface for visualizing dependency graphs, designed for large projects:

import (
    "github.com/pubgo/dix/v2/dixhttp"
    "github.com/pubgo/dix/v2/dixinternal"
)

server := dixhttp.NewServer((*dixinternal.Dix)(di))
server.ListenAndServe(":8080")

Visit http://localhost:8080 to view the dependency graph.

Security: exposes dependency graphs, provider source locations, runtime errors, and trace data. Use on localhost or private networks only. Do not expose publicly without authentication.

Highlights:

• 🔍 Fuzzy Search - Quickly locate types or functions
• 📦 Package Grouping - Collapsible sidebar browsing
• 🔄 Bidirectional Tracking - Show both dependencies and dependents
• 📏 Depth Control - Limit display levels (1-5 or all)
• 🎨 Modern UI - Tailwind CSS + Alpine.js

See dixhttp/README.md for API routes, event dictionary, and UI details.

🔍 Diagnostics

Optional observability for startup and injection troubleshooting. All file/console outputs are disabled unless configured.

Env var	Default	Purpose
DIX_TRACE_DI	off	Console step-by-step DI trace (di_trace ...)
DIX_DIAG_FILE	off	Append trace / error / llm records to JSONL
DIX_TRACE_FILE	off	Append trace-only JSONL (falls back to DIX_DIAG_FILE)

export DIX_TRACE_DI=true
export DIX_DIAG_FILE=.local/dix-diag.jsonl

In-memory trace events (dixtrace) are enabled by default and queryable through dixhttp at /api/trace.

For the full di_trace event dictionary, HTTP APIs, and UI troubleshooting workflow, see dixhttp/README.md.

🛠️ Development

# Run all tests with coverage report
task test

# Lint and format
task lint

# go vet
task vet

# HTTP visualization demo
task web-demo

GitHub Actions runs go test ./... -race and golangci-lint on push/PR.

📚 Examples

Naming follows the feature being demonstrated: inject-* for injection patterns, provide-* for provider capabilities, context-* for context integration.

Injection patterns

Example	Description
inject-func	Function type injection
inject-struct	Struct field injection (nested)
inject-method	DixInject method injection
inject-generic	Generic InjectT / InjectTContext
context-inject	Context-aware injection & trace propagation
inject-map	Map/namespace injection
inject-list	List aggregation
inject-map-list	Grouped map[string][]T aggregation
provide-multi-output	Struct multi-output provider

Runtime semantics

Example	Description
lazy	Lazy provider execution & caching
cycle	Cycle detection
singleton	Container-wide singleton sharing
error-handling	TryProvide/TryInject error handling
timeout	Provider timeout & slow-provider warning
empty-collections	Missing collections resolve to empty (or reject)

Modules

Example	Description
global	dixglobal global container
context-container	dixcontext container in Context
custom-logger	SetLog custom logging
http	HTTP visualization (end-to-end)

📖 Documentation

Document	Description
Design Document	Architecture and detailed design
Audit Report	Project audit, evaluation and comparison
dixhttp README	HTTP visualization module documentation

📄 License

MIT