4.0 KiB
✨ The little ASGI framework that shines. ✨
Introduction
Starlette is a lightweight ASGI framework/toolkit, which is ideal for building high performance asyncio services.
It is production-ready, and gives you the following:
- Seriously impressive performance.
- WebSocket support.
- GraphQL support.
- In-process background tasks.
- Startup and shutdown events.
- Test client built on
requests
. - CORS, GZip, Static Files, Streaming responses.
- 100% test coverage.
- 100% type annotated codebase.
- Zero hard dependencies.
Requirements
Python 3.6+
Installation
$ pip3 install starlette
You'll also want to install an ASGI server, such as uvicorn, daphne, or hypercorn.
$ pip3 install uvicorn
Example
from starlette.applications import Starlette
from starlette.responses import JSONResponse
import uvicorn
app = Starlette()
@app.route('/')
async def homepage(request):
return JSONResponse({'hello': 'world'})
if __name__ == '__main__':
uvicorn.run(app, host='0.0.0.0', port=8000)
Dependencies
Starlette does not have any hard dependencies, but the following are optional:
requests
- Required if you want to use theTestClient
.aiofiles
- Required if you want to useFileResponse
orStaticFiles
.python-multipart
- Required if you want to support form parsing, withrequest.form()
.graphene
- Required for GraphQL support.ujson
- Required if you want to useUJSONResponse
.
You can install all of these with pip3 install starlette[full]
.
Framework or Toolkit
Starlette is designed to be used either as a complete framework, or as an ASGI toolkit. You can use any of its components independently.
from starlette.responses import PlainTextResponse
class App:
def __init__(self, scope):
self.scope = scope
async def __call__(self, receive, send):
response = PlainTextResponse('Hello, world!')
await response(receive, send)
Run the App
application in example.py
:
$ uvicorn example:App
INFO: Started server process [11509]
INFO: Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
Modularity
The modularity that Starlette is designed on promotes building re-usable components that can be shared between any ASGI framework. This should enable an ecosystem of shared middleware and mountable applications.
The clean API separation also means it's easier to understand each component in isolation.
Performance
Our testing shows that Starlette applications running under Uvicorn as one of the fastest Python frameworks available. As an example, application performance should roughly equal or out-perform Sanic.
For high throughput loads you should:
- Make sure to install
ujson
and useUJSONResponse
. - Run using
uvicorn
, with access logging disabled.
Several of the ASGI servers also have pure Python implementations available,
so you can also run under PyPy
if your application code has parts that are
CPU constrained.
Eg. uvicorn.run(..., http='h11', loop='asyncio')
— ⭐️ —
Starlette is BSD licensed code. Designed & built in Brighton, England.