CDN画像/動画のダウンロードが遅い、またはタイムアウトする場合の対処法

{/* /etc/resolv.conf */}
nameserver 1.1.1.1        # Cloudflare
nameserver 8.8.8.8        # Google
nameserver 223.5.5.5      # AliDNS
nameserver 119.29.29.29   # DNSPod

import time
import httpx

# connect 10s; read 30s = give up after 30s with no data (not total duration)
TIMEOUT = httpx.Timeout(connect=10, read=30, write=30, pool=10)

def download(url: str, path: str, attempts: int = 4) -> str:
    for i in range(attempts):
        try:
            with httpx.stream("GET", url, timeout=TIMEOUT, follow_redirects=True) as resp:
                resp.raise_for_status()
                with open(path, "wb") as f:
                    for chunk in resp.iter_bytes(chunk_size=256 * 1024):
                        f.write(chunk)
            return path
        except httpx.HTTPError as e:
            print(f"Download failed (attempt {i + 1}): {e!r}")
            time.sleep(2 * (i + 1))
    raise RuntimeError(f"Image generated, but download failed repeatedly: {url}")

download("<CDN URL>", "output.png")

aria2c -x 8 -s 8 -k 1M --file-allocation=none "<CDN URL>"