Granian

2.7.3 · active · verified Fri Apr 10

Granian is a high-performance HTTP server for Python applications, implemented in Rust and built upon the Hyper crate. It supports ASGI/3, RSGI, and WSGI interfaces, offering robust handling for HTTP/1, HTTP/2, and Websockets. The project aims to provide a single, performant dependency solution, avoiding the typical Gunicorn + Uvicorn + http-tools stack. It is actively maintained with regular patch and minor releases, compatible with Python 3.10 and above.

Warnings

breaking Granian dropped support for Python 3.9 and PyPy 3.9/3.10 starting from v2.6.0. Users on these versions must upgrade their Python environment to Python 3.10 or newer.
Fix: Upgrade Python to 3.10+.
gotcha Prior to v2.7.1, ASGI applications, particularly those using Django channels, might not reliably receive `websocket.disconnect` events after a server-initiated close, potentially leading to connection hangs.
Fix: Upgrade Granian to v2.7.1 or newer to ensure proper websocket disconnect event handling.
gotcha Versions prior to v2.7.1 could experience an occasional runtime thread panic (`Cannot drop pointer into Python heap without the thread being attached`) during websocket cleanup on shutdown.
Fix: Upgrade Granian to v2.7.1 or newer to resolve the thread panic issue.
gotcha On WSGI applications, versions prior to v2.5.6 could have incorrect `PATH_INFO` values in the `environ` dictionary when the `--url-path-prefix` option was used. This could lead to incorrect routing or resource access.
Fix: Upgrade Granian to v2.5.6 or newer to ensure correct `PATH_INFO` handling.
gotcha On Unix systems, Granian v2.5.5 addressed an issue preventing startup on Python 3.14 when using the `forkserver` multiprocessing start method, by falling back to `spawn`.
Fix: Upgrade Granian to v2.5.5 or newer if experiencing startup issues on Python 3.14 with `forkserver`.

Install

pip install granian Install Granian

Imports

Server
```
from granian.server.embed import Server
```
This import is for embedding Granian programmatically within an application for advanced lifecycle management. It is currently considered experimental and only supports async protocols (ASGI/RSGI), not WSGI. Most users will interact with Granian via its command-line interface directly.

Quickstart

Create an ASGI application in a file (e.g., `main.py`), then serve it using the `granian` command-line interface. This example starts Granian on `127.0.0.1:8000` serving the ASGI application `app` from `main.py`.

# main.py
async def app(scope, receive, send):
    assert scope['type'] == 'http'
    await send({
        'type': 'http.response.start',
        'status': 200,
        'headers': [
            [b'content-type', b'text/plain'],
        ],
    })
    await send({
        'type': 'http.response.body',
        'body': b'Hello, world!',
    })

# To run from your terminal (assuming main.py is in current directory):
# granian --interface asgi main:app --port 8000

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