Python 在 Docker 容器内运行 Gunicorn 时未解析主机（超时）（weasyprint 需要这样做）

Question

我有一个 Django 应用程序在 docker 容器中运行，它使用 Gunicorn 为应用程序提供服务。 本应用使用Weasyprint生成一个PDF，动态加载一个CSS。 这个 CSS 由应用程序提供服务，并且工作正常（并立即加载）： host_pointing_to_that_same_machine.com/dynamic_css_path.css

（它不是 static 文件，它实际上是在 django 输出 CSS 的 URL 中定义的路径）

那是 weasyprint 代码：

css = weasyprint.CSS(url=request.build_absolute_uri(reverse('dynamic_css_path')))
        response = HttpResponse(pdf.write_pdf(stylesheets=[css]), content_type='application/pdf')

这会正确创建 URL，如果我使用 django 内置服务器 (python manage.py runserver) 而不是 gunicorn，一切正常，无论是在我的开发机器上还是在 docker 内的远程服务器上等等。

但是当我通过 gunicorn 提供应用程序时： gunicorn project.wsgi:application --bind 0.0.0.0:8000

然后 python 无法解析主机名，我通过以下方式证明了这一点：

1）进入docker的应用程序控制台并尝试：

docker exec -it container_name /bin/ash
# ping host_pointing_to_that_same_machine.com
# ping any_other_host_pointing_an_external_machine.com

一切都好。

2）在docker容器内进入Django的控制台：

# python manage.py shell
>>> import urllib
>>> r = urllib.request.urlopen(url='http://host_pointing_to_that_same_machine.com', timeout=10)
>>> print('status: '+str(r.status))

返回 200； 一切还好。

3）在docker容器里面输入python的shell：

# python
>>> from urllib import request
>>> r = request.urlopen(url='http://host_pointing_to_that_same_machine.com', timeout=10)
>>> print('status: '+str(r.status))
status: 200

4) 在脚本中执行这些代码行，让 Gunicorn 为它们服务：

# docker logs container_name
Internal Server Error: /admin/app_name/path_to_pdf_generating_script/
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py", line 35, in inner
    response = get_response(request)
  File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 128, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py", line 126, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/utils/decorators.py", line 142, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/views/decorators/cache.py", line 44, in _wrapped_view_func
    response = view_func(request, *args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/django/contrib/admin/sites.py", line 223, in inner
    return view(request, *args, **kwargs)
  File "/srv/apps/project/admin/PdfMakingAdmin.py", line 125, in method_called_by_the_view
    timeout=10)
  File "/usr/local/lib/python3.6/urllib/request.py", line 223, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/local/lib/python3.6/urllib/request.py", line 526, in open
    response = self._open(req, data)
  File "/usr/local/lib/python3.6/urllib/request.py", line 544, in _open
    '_open', req)
  File "/usr/local/lib/python3.6/urllib/request.py", line 504, in _call_chain
    result = func(*args)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1346, in http_open
    return self.do_open(http.client.HTTPConnection, req)
  File "/usr/local/lib/python3.6/urllib/request.py", line 1321, in do_open
    r = h.getresponse()
  File "/usr/local/lib/python3.6/http/client.py", line 1331, in getresponse
    response.begin()
  File "/usr/local/lib/python3.6/http/client.py", line 297, in begin
    version, status, reason = self._read_status()
  File "/usr/local/lib/python3.6/http/client.py", line 258, in _read_status
    line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")
  File "/usr/local/lib/python3.6/socket.py", line 586, in readinto
    return self._sock.recv_into(b)
socket.timeout: timed out

但是如果我更改代码而不是 host_pointing_to_that_same_machine.com 尝试加载任何未指向该机器的域，例如http://example.com或任何东西：

# docker logs container_name
status: 200

我将采用其他数千种方法中的任何一种来实现我想要的结果，但是，这仍然困扰着我，我想知道这个问题和潜在的答案是否会对面临这个问题的其他人有用，无论他们是尝试使用 Weasyprint 或任何其他需要进行 http 查询的脚本。

我在这里留下了 weasyprint 在尝试原始代码时抛出的完整回溯：

Environment:


Request Method: GET
Request URL: http://host_pointing_to_that_same_machine.com/admin/path-to-app/

Django Version: 2.0
Python Version: 3.6.8

Traceback:

File "/usr/local/lib/python3.6/site-packages/weasyprint/urls.py" in fetch
  284.         result = url_fetcher(url)

File "/usr/local/lib/python3.6/site-packages/weasyprint/urls.py" in default_url_fetcher
  248.                            timeout=timeout, context=ssl_context)

File "/usr/local/lib/python3.6/urllib/request.py" in urlopen
  223.     return opener.open(url, data, timeout)

File "/usr/local/lib/python3.6/urllib/request.py" in open
  526.         response = self._open(req, data)

File "/usr/local/lib/python3.6/urllib/request.py" in _open
  544.                                   '_open', req)

File "/usr/local/lib/python3.6/urllib/request.py" in _call_chain
  504.             result = func(*args)

File "/usr/local/lib/python3.6/urllib/request.py" in http_open
  1346.         return self.do_open(http.client.HTTPConnection, req)

File "/usr/local/lib/python3.6/urllib/request.py" in do_open
  1321.             r = h.getresponse()

File "/usr/local/lib/python3.6/http/client.py" in getresponse
  1331.                 response.begin()

File "/usr/local/lib/python3.6/http/client.py" in begin
  297.             version, status, reason = self._read_status()

File "/usr/local/lib/python3.6/http/client.py" in _read_status
  258.         line = str(self.fp.readline(_MAXLINE + 1), "iso-8859-1")

File "/usr/local/lib/python3.6/socket.py" in readinto
  586.                 return self._sock.recv_into(b)

During handling of the above exception (timed out), another exception occurred:

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  35.             response = get_response(request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  128.                 response = self.process_exception_by_middleware(e, request)

File "/usr/local/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  126.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/usr/local/lib/python3.6/site-packages/django/utils/decorators.py" in _wrapped_view
  142.                     response = view_func(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  44.         response = view_func(request, *args, **kwargs)

File "/usr/local/lib/python3.6/site-packages/django/contrib/admin/sites.py" in inner
  223.             return view(request, *args, **kwargs)

File "/srv/apps/app_name/admin/PdfAdmin.py" in attendee_list
  134.         css = weasyprint.CSS(url=request.build_absolute_uri(reverse('view_to_dynamic_css')))

File "/usr/local/lib/python3.6/site-packages/weasyprint/__init__.py" in __init__
  322.         with result as (source_type, source, base_url, protocol_encoding):

File "/usr/local/lib/python3.6/contextlib.py" in __enter__
  81.             return next(self.gen)

File "/usr/local/lib/python3.6/site-packages/weasyprint/__init__.py" in _select_source
  407.         with fetch(url_fetcher, url) as result:

File "/usr/local/lib/python3.6/contextlib.py" in __enter__
  81.             return next(self.gen)

File "/usr/local/lib/python3.6/site-packages/weasyprint/urls.py" in fetch
  286.         raise URLFetchingError('%s: %s' % (type(exc).__name__, str(exc)))

Exception Type: URLFetchingError at /admin/app_name/path-to-pdf-generator/
Exception Value: timeout: timed out

Answer 1

在示例中，您正在访问http://host_pointing_to_that_same_machine.com，但在错误日志中，我看到您正在尝试访问http://host_pointing_to_that_same_machine.com/admin/path-to-app/

Answer 2

如果主机指向同一台机器，您需要通过在 \etc\hosts 文件中创建主机条目来解析主机。 对于 docker 容器，您可以通过将以下配置包含到您的作曲家文件中来做到这一点：

extra_hosts:
  - "host_pointing_to_that_same_machine.com:192.168.X.X"

将 ip 替换为您指向 ip 的域。注意：如果有多个容器，您可能还需要为其他容器包含 extra_hosts。

Answer 3

对我来说也有同样的事情，解决方案是我只和一名工人一起通过 gunicorn 运行了 django，就像这样：

  python manage.py migrate && 
gunicorn your_project.wsgi:application --bind 0.0.0.0:8888

解决方案是将 gunigorn worker 从 1 增加到 2 ），并使用 --workers 选项：

python manage.py migrate &&
gunicorn your_project.wsgi:application --workers=3 --bind 0.0.0.0:8888