pip install -r requirements.txt

./main.py

In this example we are creating a HTTP server that has two routes:

1. `GET /` - triggers the creation of submission on Judge0

2. `PUT /callback` - called by Judge0 once the submission is done

When you run the HTTP server you should visit `http://localhost:8000` and that will create a new submission on Judge0. This submission will have a `callback_url` attribute set which Judge0 will call `PUT` HTTP verb once the submission is done.

For this to work the `callback_url` must be publicly accessible, so in this example we are using a free service https://localhost.run that allows us to expose your local HTTP server and make it available on the internet and accessible by Judge0.

Once the submission is done Judge0 will call our second route `PUT /callback` and in your terminal you should see the result.

from fastapi import FastAPI, Depends

from pydantic import BaseModel

import uvicorn

import asyncio

import judge0

class CallbackResponse(BaseModel):

created_at: str

finished_at: str

language: dict

status: dict

stdout: str

class AppContext:

def __init__(self):

self.public_url = ""

LOCAL_SERVER_PORT = 8000

app = FastAPI()

app_context = AppContext()

def get_app_context():

return app_context

async def root(app_context=Depends(get_app_context)):

if not app_context.public_url:

return {

"message": "Public URL is not available yet. Try again after a few seconds."

}

submission = judge0.Submission(

source_code="print('Hello, World!')",

language_id=judge0.PYTHON,

callback_url=f"{app_context.public_url}/callback",

)

return judge0.async_execute(submissions=submission)

async def callback(response: CallbackResponse):

print(f"Received: {response}")

async def run_ssh_tunnel():

app_context = get_app_context()

command = [

"ssh",

"-o",

"StrictHostKeyChecking=no",

"-o",

"ServerAliveInterval=30",

"-R",

f"80:localhost:{LOCAL_SERVER_PORT}",

"localhost.run",

]

process = await asyncio.create_subprocess_exec(

*command, stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.STDOUT

)

while True:

line = await process.stdout.readline()

if not line:

break

decoded_line = line.decode().strip()

if decoded_line.endswith(".lhr.life"):

app_context.public_url = decoded_line.split()[-1].strip()

await process.wait()

async def run_server():

config = uvicorn.Config(

app, host="127.0.0.1", port=LOCAL_SERVER_PORT, workers=5, loop="asyncio"

)

server = uvicorn.Server(config)

await server.serve()

async def main():

await asyncio.gather(run_ssh_tunnel(), run_server())

if __name__ == "__main__":

asyncio.run(main())