Container Service¶

A centralized dependency injection system that makes FastAPI development simpler by automatically managing service dependencies.

Why Container Service?¶

FastAPI's Depends() system is excellent for request-scoped dependencies. FastEdgy's Container Service builds on this foundation to simplify application-level services that live beyond individual requests.

While FastAPI handles request-specific data beautifully, managing application services (databases, caches, email services) often requires repetitive provider functions:

# FastAPI approach - works great but requires setup
def get_database():
    return DatabaseService("postgresql://...")

def get_email_service(db: DatabaseService = Depends(get_database)):
    return EmailService(db)

@app.post("/users")
async def create_user(
    user_data: dict,
    db: DatabaseService = Depends(get_database),
    email: EmailService = Depends(get_email_service)
):
    # Each service needs its provider function

Container Service adds a layer of convenience for these application services, automatically resolving their dependencies:

# Container Service - built on FastAPI's foundation
from fastedgy.dependencies import Inject

@app.post("/users")
async def create_user(
    user_data: dict,
    email: EmailService = Inject(EmailService)  # Auto-resolved!
):
    # Dependencies resolved automatically, no provider functions needed

Key Benefits¶

• Zero boilerplate - No provider functions needed
• Automatic resolution - Dependencies resolved recursively
• Application singletons - Services persist across requests
• Unified access - Same services in API, CLI, and background tasks
• Full FastAPI compatibility - Built on native dependency system

Quick Start¶

New to Container Service? Start here:

Get Started →

Documentation Structure¶

When to Use Container Service¶

Perfect for:

• Database connections and configurations
• Email services, caches, external APIs
• Services shared across endpoints
• Application-level singletons

Not needed for:

• Simple request-scoped data
• FastAPI's built-in features (authentication, etc.)
• One-off utilities

Get Started