The Complete Production SOP: How to Deploy and Run HTTPX Modern Asynchronous & Synchronous HTTP Client in Autonomous AI Agents

---
name: "httpx-async-http-client"
description: "Make asynchronous HTTP requests with HTTP/2 support, connection pooling, and connection timeouts."
metadata:
  author: "Encode"
  version: "1.0.0"
  runtime_compatibility:
    - "codex"
    - "claude-code"
    - "cursor"
    - "windsurf"
triggers:
  - "async http request httpx"
  - "configure httpx connection pool"
  - "stream large file httpx"
permissions:
  fs_read: true
  fs_write: "workspace"
  shell_exec: false
  net_access: false
---

import os
import httpx

limits = httpx.Limits(
    max_keepalive_connections=int(os.getenv("HTTPX_POOL_KEEPALIVE", "20")),
    max_connections=int(os.getenv("HTTPX_POOL_MAX_CONNECTIONS", "100")),
    keepalive_expiry=30.0,
)
timeout = httpx.Timeout(connect=5.0, read=15.0, write=5.0, pool=10.0)

async def get_client() -> httpx.AsyncClient:
    return httpx.AsyncClient(limits=limits, timeout=timeout, http2=True)

import httpx
from pathlib import Path

async def stream_large_file(url: str, destination: Path) -> None:
    timeout = httpx.Timeout(connect=10.0, read=60.0, write=10.0, pool=5.0)
    async with httpx.AsyncClient(timeout=timeout, http2=True) as client:
        async with client.stream("GET", url) as response:
            response.raise_for_status()
            with open(destination, "wb") as buffer:
                async for chunk in response.aiter_bytes(chunk_size=8192):
                    buffer.write(chunk)

import pytest
import httpx
import respx

@pytest.mark.asyncio
@respx.mock
async def test_async_fetch():
    mock_route = respx.get("https://api.example.internal/items").respond(
        status_code=200,
        json={"status": "ok", "items": [1, 2, 3]}
    )
    async with httpx.AsyncClient(http2=True) as client:
        response = await client.get("https://api.example.internal/items")
    assert response.status_code == 200
    assert response.json()["status"] == "ok"
    assert mock_route.called