✨ The little ASGI framework that shines. ✨
Documentation: https://www.starlette.io/
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.
- 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.
Python 3.6+
$ pip3 install starlette
You'll also want to install an ASGI server, such as uvicorn, daphne, or hypercorn.
$ pip3 install uvicorn
from starlette.applications import Starlette
from starlette.responses import JSONResponse
import uvicorn
app = Starlette()
@app.route('/')
asnyc def homepage(request):
return JSONResponse({'hello': 'world'})
if __name__ == '__main__':
uvicorn.run(app, host='0.0.0.0', port=8000)
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()
.ujson
- Required if you want to useUJSONResponse
.
You can install all of these with pip3 install starlette[full]
.
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)
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.
Independent TechEmpower benchmarks show Starlette applications running under Uvicorn as one of the fastest Python frameworks available. (*)
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')
(*) TechEmpower continuous benchmarking results, from 13th Sept 2018. Filtered to JavaScript, Python, and Ruby frameworks backed by Postgres, for comparision against similar candidates. To be updated to Round 17 once available.
— ⭐️ —
Starlette is BSD licensed code. Designed & built in Brighton, England.