将Python脚本作为systemd服务运行,连接到InfluxDB导致ConnectionError

问题描述 投票:-1回答:1

我正在运行一个shell脚本作为Ubuntu的systemd服务,在启动时启动。该脚本在内部执行连接到InfluxDB的Python脚本(python_simulator.py)(通过Python的Influxdb包)。

Python脚本无法在启动时启动,并且检查日志表明这是因为连接到InfluxDB时出现'ConnectionError'。我将其解释为,当Python服务在启动时激活时,flowxdb服务可能尚未启动。所以我试图通过添加“After”和“Wants”作为“Influxdb.service”来添加服务中的顺序依赖,它在Influxdb服务后几秒钟激活Python服务。但是,我仍然得到相同的连接错误。

systemd服务(myservice.service)看起来像:

[Unit]
Description= Python startup service.
After=influxdb.service
Wants=influxdb.service

[Service]
Type=forking
ExecStart=/bin/bash /home/test_user/Deploy/start.sh
ExecStop=/bin/bash /home/test_user/Deploy/stop.sh

[Install]
WantedBy=multi-user.target

Python脚本的日志文件(python_simulator.py):

Traceback (most recent call last):
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connection.py", line 159, in _new_conn
    (self._dns_host, self.port), self.timeout, **extra_kw)
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/util/connection.py", line 80, in create_connection
    raise err
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/util/connection.py", line 70, 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 "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connectionpool.py", line 600, in urlopen
    chunked=chunked)
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connectionpool.py", line 354, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.6/http/client.py", line 1239, in request
    self._send_request(method, url, body, headers, encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1285, in _send_request
    self.endheaders(body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1234, in endheaders
    self._send_output(message_body, encode_chunked=encode_chunked)
  File "/usr/lib/python3.6/http/client.py", line 1026, in _send_output
    self.send(msg)
  File "/usr/lib/python3.6/http/client.py", line 964, in send
    self.connect()
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connection.py", line 181, in connect
    conn = self._new_conn()
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connection.py", line 168, in _new_conn
    self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x7f817d91b400>: 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 "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/requests/adapters.py", line 449, in send
    timeout=timeout
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/connectionpool.py", line 638, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/urllib3/util/retry.py", line 399, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='localhost', port=8086): Max retries exceeded with url: /query?q=SHOW+DATABASES (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f817d91b400>: Failed to establish a new connection: [$

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "python_simulator.py", line 467, in <module>
    main(host=args.host, port=args.port)
  File "python_simulator.py", line 312, in main
    for db_dict in client.get_list_database():
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/influxdb/client.py", line 570, in get_list_database
    return list(self.query("SHOW DATABASES").get_points())
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/influxdb/client.py", line 416, in query
    expected_response_code=expected_response_code
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/influxdb/client.py", line 267, in request
    timeout=self._timeout
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/requests/sessions.py", line 533, in request
    resp = self.send(prep, **send_kwargs)
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/requests/sessions.py", line 646, in send
    r = adapter.send(request, **kwargs)
  File "/home/test_user/Deploy/py_venv/lib/python3.6/site-packages/requests/adapters.py", line 516, in send
    raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='localhost', port=8086): Max retries exceeded with url: /query?q=SHOW+DATABASES (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x7f817d91b400>: Failed to establish a new connection$

最后,阻止守护进程树显示myservice.service在Influxdb.service之后执行:

myservice.service +6.872s
└─influxdb.service @11.344s
  └─network-online.target @11.337s
    └─NetworkManager-wait-online.service @4.706s +6.630s
      └─NetworkManager.service @3.940s +674ms
        └─dbus.service @3.914s
          └─basic.target @3.728s
            └─sockets.target @3.728s
              └─snapd.socket @3.722s +5ms
                └─sysinit.target @3.712s
                  └─apparmor.service @3.276s +435ms
                    └─local-fs.target @3.266s
                      └─run-user-1000.mount @49.841s
                        └─swap.target @3.160s
                          └─dev-disk-by\x2duuid-16e1b46a\x2d79fc\x2d4965\x2d9932\x2d8f589e9e7057.swap @3.132s +23ms
                            └─dev-disk-by\x2duuid-16e1b46a\x2d79fc\x2d4965\x2d9932\x2d8f589e9e7057.device @3.130s

我不知道为什么我仍然无法使用Influxdb执行脚本(python_simulator.py)。还有其他依赖吗? myservice.service是否需要进行任何更改?任何帮助将不胜感激。

编辑1:

原因可能是ConnectionRefusedError而不是ConnectionError,这可能是因为当它连接到8086端口的涌入时,什么都没有在监听它?如果是这样,我怎么能按顺序排列呢?

python systemd influxdb influxdb-python system-services
1个回答
1
投票

即使您创建了服务依赖项,您仍可能遇到问题(因为在它准备好接受连接之前,涌入dbldb可能需要一些时间,在此期间Python代码可能会启动)。解决方案是:

  • 编写Python代码以在拒绝或重新连接时重试连接
  • 配置systemd以在服务失败时重新启动服务。

如果没有看到你的Python代码,很难建议第一个解决方案可能是什么样的,但是将你的单元配置为在失败时重新启动就像在[Service]部分添加以下内容一样简单:

Restart=on-failure

您可以通过向systemd单元添加一个小的shell脚本来延迟启动Python代码,直到Influxdb准备就绪:

ExecStartPre=/bin/sh -c 'while ! curl -sf http://localhost:8086/ping; do sleep 1; done'

这将无限循环(从而阻止服务启动),直到Influxdb成功响应/ping端点。

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