version: 1
id: python-async-service
title: Build an Async Python Service
summary: Use asyncio with Python's standard library to serve health and payment responses concurrently.
difficulty: advanced
estimatedMinutes: 40
prerequisites: [python-json-api]
image: python:3.12-alpine
shell: /bin/sh
setup:
  - "apk add --no-cache wget iproute2 >/dev/null"
  - "mkdir -p /workspace"
tasks:
  - id: async-service
    title: Serve HTTP responses with asyncio
    description: 'Create /workspace/server.py using asyncio.start_server on :8080. Return ok for GET /health and [{"id":1,"amount":25}] for GET /payments with Content-Type application/json. Run it in the background.'
    hints:
      - 'asyncio.start_server can accept a coroutine that reads from StreamReader and writes to StreamWriter.'
      - 'Parse the first request line to route /health and /payments.'
      - 'Use writer.write(...) followed by await writer.drain().'
    checks:
      - type: file
        name: Server module present
        path: /workspace/server.py
        value: "asyncio"
      - type: file
        name: Uses asyncio server
        path: /workspace/server.py
        value: "start_server"
      - type: file
        name: Payments route present
        path: /workspace/server.py
        value: "/payments"
      - type: file
        name: JSON content type present
        path: /workspace/server.py
        value: application/json
      - type: port
        name: Port 8080 listening
        port: 8080
      - type: command
        name: Health returns ok
        command: "wget -qO- http://127.0.0.1:8080/health | grep -q '^ok$'"
      - type: command
        name: Payments JSON body
        command: "wget -qO- http://127.0.0.1:8080/payments | grep -q '\"amount\": 25\\|\"amount\":25'"
      - type: command
        name: JSON content type
        command: "wget -S -qO- http://127.0.0.1:8080/payments 2>&1 | grep -qi 'content-type: application/json'"
limits: {cpus: "1.0", memory: 256m, pids: 128, timeout: 1800, network: true}