Tokamak is a pure-Python router based on Radix trees intended for ASGI Python applications.
There are many HTTP routers based on radix trees available in other language communities, including Go, Javascript, Rust, and others. In Python, however, most open-source Python web frameworks instead utilize lists to store and look up HTTP routes.
The primary goal for this project is to provide a radix-tree-based router for Python web frameworks (or any custom ASGI or WSGI implementation).
This library is experimental. Use at your own risk.
As a secondary goal, a minimal and highly experimental web framework is included an optional install in this library.
The reasons for including this web framework are as follows:
- It provides a convenient way to test the
AsgiRouterclass, and - It allows the authors of this library to explore experimental ASGI-framework features, including request-cancellation, background task time-limits, and background task cancellation.
Developers should consider more fully-featured web frameworks before this one and there are many to choose from:
You can install tokamak with:
pip install tokamakBy default tokamak has no dependencies.
If you would like to try out the experimental web framework, you can install with optional extras web, which will include trio:
$ pip install "tokamak[web]"
...This library provides a radix tree implementation and a basic AsgiRouter router implementation for low-level ASGI applications. You can use the AsgiRouter class as follows.
First, we start with some with some imports and some fallback handlers:
from hypercorn.config import Config
from hypercorn.trio import serve
import trio
from tokamak import AsgiRouter, Route
from tokamak.router import MethodNotAllowed, UnknownEndpoint
# # Fallback Handlers # #
async def method_not_allowed(scope, receive, send):
await send(
{
"type": "http.response.start",
"status": 405,
"headers": [(b"Content-Type", b"text/html; charset=UTF-8")],
}
)
await send(
{
"type": "http.response.body",
"body": b"<html><body><h1>405 Method not allowed</h1></body></html>",
}
)
async def unknown_handler(scope, receive, send):
await send(
{
"type": "http.response.start",
"status": 404,
"headers": [(b"Content-Type", b"text/html; charset=UTF-8")],
}
)
await send(
{
"type": "http.response.body",
"body": b"<html><body><h1>404 Not Found!</h1></body></html>",
}
)Next we'll build two different application endpoint handlers. These do roughly the same thing, so this is purely for demonstration purposes:
async def index(path_context, scope, receive, send):
message = await receive()
if message["type"] == "http.request":
body = message.get("body", b"")
# here's our response:
await send({"type": "http.response.start", "status": 200})
await send({"type": "http.response.body", "body": body if body else b"OK"})
elif message["type"] == "http.disconnect":
print("Disconnected! ")
async def other_handler(path_context, scope, receive, send):
context = bytes(json.dumps(path_context), encoding="utf-8")
message = await receive()
if message["type"] == "http.request":
body = message.get("body", b"")
await send({"type": "http.response.start", "status": 200})
await send({"type": "http.response.body", "body": body if body else context})
elif message["type"] == "http.disconnect":
print("Disconnected! ")Finally, we can build an AsgiRouter and a working ASGI app, like this:
# `AsgiRouter` and `Route` class provided by this library
ROUTER = AsgiRouter(
routes=[
Route("/", handler=index, methods=["GET"]),
# Routes will match on regexes and bind to variables
# given on the left side of the colon
Route(
"/other_handler/{name:[a-z1-9]+}", handler=other_handler, methods=["POST"],
),
]
)
# This is a basic implementation of the ASGI spec
# See: https://asgi.readthedocs.io/en/latest/specs/main.html
async def asgi_app(scope, receive, send):
path = scope.get("path", "")
try:
# Routers provider a `get_route` method
# If no route is matched, they throw `UnknownEndpoint`
# If a route is matched, we'll get path context and a handler
handler, context = ROUTER.get_route(path)
except UnknownEndpoint:
await unknown_handler(scope, receive, send)
return None
try:
# If a matched router doesn't handle this method
# it will throw `MethodNotAllowed`
await handler(context, scope, receive, send, method=scope.get("method"))
except MethodNotAllowed:
await method_not_allowed(scope, receive, send)
return None
async def app_with_lifespan(scope, receive, send):
if scope["type"] == "lifespan":
while True:
message = await receive()
if message["type"] == "lifespan.startup":
await send({"type": "lifespan.startup.complete"})
elif message["type"] == "lifespan.shutdown":
await send({"type": "lifespan.shutdown.complete"})
return
if scope["type"] == "http":
return await asgi_app(scope, receive, send)Finally, to run our ASGI app, we'll add the following:
if __name__ == "__main__":
config = Config()
config.bind = ["localhost:8000"]
trio.run(partial(serve, app_with_lifespan, config))This example relies on the following dependencies:
- hypercorn
- trio
If we have these dependencies in our Python environment, we can run this simple script:
$ poetry run python examples/asgi_minimal.py
[2022-03-20 16:59:58 -0700] [91988] [INFO] Running on http://127.0.0.1:8000 (CTRL + C to quit)In a separate terminal, we can try it out like so:
❯ curl http://localhost:8000/
OK
# No capital letters matched
❯ curl -XPOST http://localhost:8000/other_handler/bla1AA
<html><body><h1>404 Not Found!</h1></body></html>
# GET not POST -> 405
❯ curl http://localhost:8000/other_handler/bla
<html><body><h1>405 Method not allowed</h1></body></html>
# Success
❯ curl -XPOST http://localhost:8000/other_handler/bla1
{"name": "bla1"}Note: that our regex path does not match capital letters, so that request 404s.
Runnable examples are provided in the examples directory. For instance, you can run the experimental tokamak application with trio and hypercorn like so:
$ poetry install -E "full"
Installing dependencies from lock file
Package operations: 8 installs, 0 updates, 0 removals
• Installing h11 (0.13.0)
• Installing hpack (4.0.0)
• Installing hyperframe (6.0.1)
• Installing h2 (4.1.0)
• Installing priority (2.0.0)
• Installing toml (0.10.2)
• Installing wsproto (1.1.0)
• Installing hypercorn (0.13.2)
Installing the current project: tokamak (0.2.1)
❯ poetry run python examples/tokamak_app.py
========·°·°~> Starting tokamak °°···°°🚀···°°
[2022-03-20 11:05:01 -0700] [63023] [INFO] Running on http://127.0.0.1:8000 (CTRL + C to quit)In a separate terminal, you can make various requests, such as the following:
❯ curl http://localhost:8000
{"received": {}}
❯ curl http://localhost:8000/info/erik -d '{"some_data": "something"}'
{"received": {"some_data": "something"}}Back in the first terminal, where you launched the example tokamak application, you should see the following:
❯ poetry run python examples/tokamak_app.py
========·°·°~> Starting tokamak °°···°°🚀···°°
[2022-03-20 11:05:01 -0700] [63023] [INFO] Running on http://127.0.0.1:8000 (CTRL + C to quit)
{} {'type': 'http', 'http_version': '1.1', 'asgi': {'spec_version': '2.1', 'version': '3.0'}, 'method': 'GET', 'scheme': 'http', 'path': '/', 'raw_path': b'/', 'query_string': b'', 'root_path': '', 'headers': <Headers([(b'host', b'localhost:8000'), (b'user-agent', b'curl/7.81.0'), (b'accept', b'*/*')])>, 'client': ('127.0.0.1', 55379), 'server': ('127.0.0.1', 8000), 'extensions': {}} <Headers([(b'host', b'localhost:8000'), (b'user-agent', b'curl/7.81.0'), (b'accept', b'*/*')])> b'' 1.1 GET
Sleeping 1s for total seconds: 0
Sleeping 1s for total seconds: 1
Sleeping 1s for total seconds: 2
Sleeping 1s for total seconds: 3
Sleeping 1s for total seconds: 4
{'user': 'erik'} {'type': 'http', 'http_version': '1.1', 'asgi': {'spec_version': '2.1', 'version': '3.0'}, 'method': 'POST', 'scheme': 'http', 'path': '/info/erik', 'raw_path': b'/info/erik', 'query_string': b'', 'root_path': '', 'headers': <Headers([(b'host', b'localhost:8000'), (b'user-agent', b'curl/7.81.0'), (b'accept', b'*/*'), (b'content-length', b'26'), (b'content-type', b'application/x-www-form-urlencoded')])>, 'client': ('127.0.0.1', 55386), 'server': ('127.0.0.1', 8000), 'extensions': {}} <Headers([(b'host', b'localhost:8000'), (b'user-agent', b'curl/7.81.0'), (b'accept', b'*/*'), (b'content-length', b'26'), (b'content-type', b'application/x-www-form-urlencoded')])> b'' 1.1 POST
Sleeping 1s for total seconds: 0
Sleeping 1s for total seconds: 5
Sleeping 1s for total seconds: 1
Sleeping 1s for total seconds: 6
Sleeping 1s for total seconds: 2
Sleeping 1s for total seconds: 7
Sleeping 1s for total seconds: 3
Sleeping 1s for total seconds: 8