svcs: A Flexible Service Locator

25.1.0 · active · verified Thu Apr 09

svcs is a flexible service locator for Python applications, simplifying dependency management and resource cleanup. It currently stands at version 25.1.0 and typically releases new versions every 1-2 months, incorporating bug fixes, minor features, and framework integrations.

Warnings

breaking The handling of context managers passed to `register_value()` changed in version 23.21.0. Previously, `svcs` would NOT enter/exit context managers registered this way. Post 23.21.0, `svcs` WILL automatically enter and exit them by default.
Fix: If you were passing context managers to `register_value()` and managing their lifecycle manually, explicitly add `enter=False` to `register_value()` calls to maintain the old behavior, or switch to `register_factory()` if you want `svcs` to manage it.
gotcha Failing to close `svcs.Container` or `svcs.Registry` instances with pending cleanups will raise a `ResourceWarning`.
Fix: Always ensure containers are properly closed. The recommended way is to use `with svcs.Container(...) as container:` for automatic cleanup. For registries, ensure any registered context managers or asynchronous cleanups are explicitly managed.

Install

pip install svcs Install core library

Imports

Registry
```
from svcs import Registry
```
Container
```
from svcs import Container
```
svcs_from_factory
```
from svcs import svcs_from_factory
```
Commonly used for framework integrations or when explicit registration of a callable factory is needed.

Quickstart

This quickstart demonstrates how to define a service, register it with `svcs.Registry` using a factory function, and then acquire and use it via `svcs.Container`. It also shows the recommended practice of using a `with` statement for automatic container cleanup.

import svcs

class MyService:
    def __init__(self, name: str):
        self.name = name

    def hello(self) -> str:
        return f"Hello from {self.name}!"

def create_my_service() -> MyService:
    return MyService(name="quickstart_service")

# 1. Create a registry and register your service factory
reg = svcs.Registry()
reg.register_factory(MyService, create_my_service)

# 2. Get a container, ensuring it's closed properly
with svcs.Container(reg) as container:
    # 3. Acquire the service
    service = container.get(MyService)
    print(service.hello())

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