价格监测的代理

import random, time
import requests

# s4m authenticated datacenter proxy
HTTP_PROXY  = "http://USER:PASS@proxy.s4m.online:3128"        # HTTP/HTTPS
# SOCKS_PROXY = "socks5://USER:PASS@proxy.s4m.online:1080"   # pip install requests[socks]

proxies = {"http": HTTP_PROXY, "https": HTTP_PROXY}

session = requests.Session()
session.proxies.update(proxies)
session.headers.update({
    # a real, contactable UA reads as a monitoring tool, not an attack
    "User-Agent": "price-monitor/1.0 (+ops@yourco.example)",
})

targets = [
    "https://shop.example.com/product/1001",
    "https://shop.example.com/product/1002",
]

def fetch(url, tries=4):
    for attempt in range(tries):
        r = session.get(url, timeout=20)
        if r.status_code in (429, 503):        # rate-limited: back off
            time.sleep(2 ** attempt + random.random())
            continue
        r.raise_for_status()
        return r.text
    raise RuntimeError(f"gave up on {url}")

for url in targets:
    html = fetch(url)
    print(url, len(html), "bytes")
    time.sleep(random.uniform(2, 6))           # jitter between requests