如何解决Python中HTTPSConnectionPool的Max retries exceeded错误？

requests代码本地运行正常，但部署到服务器后出现连接失败错误：

ConnectionError at /api/check-car/
HTTPSConnectionPool(host='example.uz', port=443): Max retries exceeded with url: /api/token/ (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7f3d48892f50>: Failed to establish a new connection: [Errno 111] Connection refused'))

涉及的核心代码如下：

def post(self, request):
    base_url = os.environ.get('AUTH_URL', 'http://localhost')
    # 向认证端点发送POST请求

    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
                      "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36",
        'accept': 'application/json',
        'Content-Type': 'application/json',
    }

    json_data = {
        'username': os.environ.get("GARAJ_USERNAME", "admin"),
        'password': os.environ.get("GARAJ_PASSWORD", "admin123"),
    }
    response = requests.post(base_url + '/api/token/', json=json_data, headers=headers)

    # 检查响应状态码
    if response.status_code == 200:
        data = response.json()
        # 从响应中提取JWT token
        jwt_token_access = data['access']
        # 在后续请求中携带JWT token
        headers['Authorization'] = f'Bearer {jwt_token_access}'
        auth_url = base_url + '/api/boshqarma/avto/'
        response = requests.get(auth_url, headers=headers)

        for x in response.json()['results']:
            if x["davlat_raqami"] == request.data['avto_raqami']:
                boshqarma = x["boshqarma"]
                response = requests.get(base_url + f'/api/boshqarma/boshqarma/{boshqarma}/', headers=headers)
                tuman = response.json()['tuman']
                response = requests.get(base_url + f'/api/boshqarma/bolim/{tuman}/', headers=headers)
                tuman = response.json()['tuman']
                tuman = Tuman.objects.get(tuman_nomi=tuman)
                data = {'tuman_id': tuman.id}
                response = Response(data)
                return response
        else:
            return Response("Xato avto raqam")

    else:
        return Response(response)

• 排查服务器间网络连通性：在部署代码的客户端服务器上执行curl -v https://example.uz/api/token/，确认能否和宿主服务器建立连接。如果连接被拒绝，重点检查：
  • 宿主服务器的防火墙/安全组是否允许客户端服务器的IP访问443端口；
  • 宿主服务器的Web服务（如Nginx、Apache）是否正常监听443端口，服务是否运行；
  • 宿主服务器的HTTPS证书是否有效，避免因证书验证失败导致连接中断。
• 验证环境变量配置：确认服务器上的AUTH_URL是否正确设置为https://example.uz（而非本地默认的http://localhost），同时检查GARAJ_USERNAME和GARAJ_PASSWORD是否与宿主服务器的认证凭据匹配。
• 添加超时与重试机制：原代码未设置请求超时，且无重试策略，容易因临时网络问题触发错误。可以修改代码使用Session配置重试，并添加超时参数：

  import requests
  from requests.adapters import HTTPAdapter
  from urllib3.util.retry import Retry
  
  def post(self, request):
      base_url = os.environ.get('AUTH_URL', 'http://localhost')
      # 配置Session和重试策略
      session = requests.Session()
      retry_strategy = Retry(
          total=3,
          backoff_factor=0.5,
          status_forcelist=[429, 500, 502, 503, 504],
      )
      adapter = HTTPAdapter(max_retries=retry_strategy)
      session.mount("https://", adapter)
      session.mount("http://", adapter)
  
      headers = {
          "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) "
                        "AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36",
          'accept': 'application/json',
          'Content-Type': 'application/json',
      }
  
      json_data = {
          'username': os.environ.get("GARAJ_USERNAME", "admin"),
          'password': os.environ.get("GARAJ_PASSWORD", "admin123"),
      }
      # 添加超时参数，避免请求挂起
      token_response = session.post(base_url + '/api/token/', json=json_data, headers=headers, timeout=10)
  
      if token_response.status_code == 200:
          data = token_response.json()
          jwt_token_access = data['access']
          headers['Authorization'] = f'Bearer {jwt_token_access}'
          auth_url = base_url + '/api/boshqarma/avto/'
          # 区分不同请求的响应变量，避免覆盖
          avto_response = session.get(auth_url, headers=headers, timeout=10)
  
          for x in avto_response.json()['results']:
              if x["davlat_raqami"] == request.data['avto_raqami']:
                  boshqarma = x["boshqarma"]
                  boshqarma_response = session.get(base_url + f'/api/boshqarma/boshqarma/{boshqarma}/', headers=headers, timeout=10)
                  tuman = boshqarma_response.json()['tuman']
                  bolim_response = session.get(base_url + f'/api/boshqarma/bolim/{tuman}/', headers=headers, timeout=10)
                  tuman = bolim_response.json()['tuman']
                  tuman = Tuman.objects.get(tuman_nomi=tuman)
                  return Response({'tuman_id': tuman.id})
          else:
              return Response("Xato avto raqam")
  
      else:
          return Response(token_response.text, status=token_response.status_code)
  

• 检查宿主服务器服务状态：登录宿主服务器，查看提供/api/token/的认证服务是否正常运行，通过systemctl status <服务名称>查看状态，或查看服务日志定位内部错误。
• 修复变量覆盖问题：原代码多次用response变量存储不同请求结果，容易导致调试困难。建议给每个请求的响应变量单独命名（如token_response、avto_response），提升代码可读性和可维护性。

内容的提问来源于stack exchange，提问作者Jakhongir Turgunboev