在Server A运行代码时遇API连接拒绝错误的解决请求

问题背景 #

在Server A上运行代码时触发连接拒绝错误，报错根源为代码行api_url = 'http://127.0.0.1:4657/embeddings'，推测目标API部署在Server B上。完整错误回溯如下：

Traceback (most recent call last):
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connection.py", line 174, in _new_conn
    conn = connection.create_connection(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/util/connection.py", line 95, in create_connection
    raise err
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/util/connection.py", line 85, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connectionpool.py", line 715, in urlopen
    httplib_response = self._make_request(
                       ^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connectionpool.py", line 416, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connection.py", line 244, in request
    super(HTTPConnection, self).request(method, url, body=body, headers=headers)
  File "/root/miniconda3/lib/python3.11/http/client.py", line 1294, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/root/miniconda3/lib/python3.11/http/client.py", line 1340, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/root/miniconda3/lib/python3.11/http/client.py", line 1289, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/root/miniconda3/lib/python3.11/http/client.py", line 1048, in _send_output
    self.send(msg)
  File "/root/miniconda3/lib/python3.11/http/client.py", line 986, in send
    self.connect()
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connection.py", line 205, in connect
    conn = self._new_conn()
           ^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connection.py", line 186, in _new_conn
    raise NewConnectionError(
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f374f413650>: Failed to establish a new connection: [Errno 111] Connection refused

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/adapters.py", line 486, in send
    resp = conn.urlopen(
           ^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/connectionpool.py", line 799, in urlopen
    retries = retries.increment(
              ^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/urllib3/util/retry.py", line 592, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='127.0.0.1', port=4657): Max retries exceeded with url: /embeddings (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f374f413650>: Failed to establish a new connection: [Errno 111] Connection refused'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/root/pritika/EaseMyTrip/Chat/main.py", line 1, in <module>
    from INTENT.intent import IntentDetector
  File "/root/pritika/EaseMyTrip/Chat/INTENT/intent.py", line 233, in <module>
    top_5 = intent.get_top_sentence_candidates("This is the first sentence.")
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/EaseMyTrip/Chat/INTENT/intent.py", line 56, in get_top_sentence_candidates
    input_embedding = self.get_input_embedding_from_api(input_sentence)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/EaseMyTrip/Chat/INTENT/intent.py", line 42, in get_input_embedding_from_api
    response = requests.post(api_url, json={'texts': input_sentence})
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/api.py", line 115, in post
    return request("post", url, data=data, json=json, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/api.py", line 59, in request
    return session.request(method=method, url=url, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/sessions.py", line 589, in request
    resp = self.send(prep, **send_kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/sessions.py", line 703, in send
    r = adapter.send(request, **kwargs)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pritika/ner/lib/python3.11/site-packages/requests/adapters.py", line 519, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='127.0.0.1', port=4657): Max retries exceeded with url: /embeddings (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f374f413650>: Failed to establish a new connection: [Errno 111] Connection refused'))

解决步骤 #

1. 修正API目标地址 #

将代码中的api_url替换为Server B的实际IP地址或域名，示例：

api_url = 'http://192.168.1.100:4657/embeddings'  # 替换为Server B的真实IP
# 或使用域名
api_url = 'http://serverb.example.com:4657/embeddings'

2. 验证Server A与Server B的网络连通性 #

在Server A终端执行以下命令，排查网络链路：

• 测试基础网络连通：ping <ServerB_IP>
• 测试端口开放状态：telnet <ServerB_IP> 4657 或 nc -zv <ServerB_IP> 4657
  若命令返回连接失败，说明网络不通或端口未对外开放，需进一步排查网络配置。

3. 检查Server B的防火墙规则 #

确保Server B的防火墙允许外部访问4657端口：

• 若使用ufw（Ubuntu/Debian）：执行sudo ufw allow 4657/tcp，再重启防火墙sudo ufw reload
• 若使用iptables（CentOS/RHEL）：执行sudo iptables -A INPUT -p tcp --dport 4657 -j ACCEPT，并保存规则

4. 确认API服务在Server B上正常运行 #

在Server B终端执行以下操作：

• 检查API进程状态：ps aux | grep <API进程名称>
• 测试本地API可用性：curl http://127.0.0.1:4657/embeddings，若返回正常响应则服务运行正常

5. 调整API服务的监听地址 #

如果API服务仅监听本地回环地址（127.0.0.1），外部无法访问。需修改配置让服务监听所有网卡（0.0.0.0）：

• 例如Flask框架，启动时指定host='0.0.0.0'：

  app.run(host='0.0.0.0', port=4657)
  

• 其他框架（FastAPI、Django）需对应调整配置文件中的监听地址参数

内容的提问来源于stack exchange，提问作者user22268432