Why not just use async Python for this API?

application.py

from fastapi import FastAPI
import requests
import httpx
import uuid
import logging

logging.basicConfig(format="%(asctime)s %(message)s")
log = logging.getLogger("myapp")
log.setLevel(logging.DEBUG)

app = FastAPI()

EXTERNAL_API_ENDPOINT = "http://localhost:8888"


@app.get("/healthcheck")
async def healthcheck():
    return {"status": "ok"}

#
# Async mixed with blocking
#


def internal_signing_op(op_num: int, request_id: str) -> None:
    session = requests.Session()
    response = session.request("GET", EXTERNAL_API_ENDPOINT, timeout=2000)
    log.debug(f"{request_id} {op_num}: {response}")


def sign_op1(request_id: str) -> None:
    internal_signing_op(1, request_id)


def sign_op2(request_id: str) -> None:
    internal_signing_op(2, request_id)


@app.get("/async-blocking")
async def root():
    request_id = str(uuid.uuid4())

    log.debug(f"{request_id}: started processing")

    sign_op1(request_id)
    sign_op2(request_id)

    log.debug(f"{request_id}: finished!")
    return {"message": "hello world"}


#
# Async end-to-end
#


async def v2_internal_signing_op(op_num: int, request_id: str) -> None:
    """Calls external API endpoint and returns the response as a dict."""
    async with httpx.AsyncClient() as session:
        response = await session.request("GET", EXTERNAL_API_ENDPOINT, timeout=2000)
    log.debug(f"{request_id} {op_num}: {response}")


async def v2_sign_op1(request_id: str) -> None:
    await v2_internal_signing_op(1, request_id)


async def v2_sign_op2(request_id: str) -> None:
    await v2_internal_signing_op(2, request_id)


@app.get("/all-async")
async def v2_root():
    request_id = str(uuid.uuid4())

    log.debug(f"{request_id}: started processing")

    await v2_sign_op1(request_id)
    await v2_sign_op2(request_id)

    log.debug(f"{request_id}: finished!")
    return {"message": "hello world"}

external_api.py

import asyncio

from fastapi import FastAPI
import time

app = FastAPI()

@app.get("/")
async def root():
    await asyncio.sleep(20)
    return {"message": "Hello World"}

requirements.txt

fastapi[all]==0.65.1
uvicorn[standard]==0.13.4
requests==2.25.1
httpx==0.18.2