如何创建存储在Google Cloud Storage中的图像的PDF？

Question

抱歉，这是一个愚蠢的问题。 我是GCP的新手。

对于Web应用程序，我需要根据Cloud Storage中存储的图像创建PDF。

首先，我尝试将python软件包fpdf与存储在Cloud Storage中的文件一起使用，看看是否可行。 因为图像是在线存储的，所以我使用urllib2来获取图像。

码：

from fpdf import FPDF
import urllib2
import os

imagelist = ["https://storage.googleapis.com/seventh-terrain-179700.appspot.com/excuses.jpg", "https://storage.googleapis.com/seventh-terrain-179700.appspot.com/excuses2.jpg"]

pdf = FPDF()
i = 0
for image in imagelist:
    image = urllib2.urlopen(image)

    # writing image files in current folder
    with open('image'+str(i)+'.jpg','wb') as output:
        output.write(image.read())

    pdf.add_page()
    pdf.image('image'+str(i)+'.jpg', 10, 10, 100, 100) # pdf.image(image,x,y,w,h)

    # removing images
    os.remove('image'+str(i)+'.jpg')
    i += 1

# Creating PDF in current folder
pdf.output("yourfile.pdf", "F")

这个话很好。

然后，我尝试在本地服务器中部署相同的代码：

import webapp2
from fpdf import FPDF
import urllib2
import os

pdf = FPDF()

class MainPage(webapp2.RequestHandler):
    def get(self):
        imagelist = ["https://storage.googleapis.com/seventh-terrain-179700.appspot.com/excuses.jpg", "https://storage.googleapis.com/seventh-terrain-179700.appspot.com/excuses2.jpg"]

        pdf = FPDF()
        i = 0
        for image in imagelist:
            image = urllib2.urlopen(image)

            with open('image'+str(i)+'.jpg','wb') as output:
                output.write(image.read())

            pdf.add_page()
            pdf.image('image'+str(i)+'.jpg', 10, 10, 100, 100) # pdf.image(image,x,y,w,h)

            os.remove('image'+str(i)+'.jpg')
            i += 1

        pdf.output("yourfile.pdf", "F")

application = webapp2.WSGIApplication([('/', MainPage)],
                                      debug=True)

但是，我得到了错误：

WARNING  2017-12-08 19:21:56,184 sandbox.py:1082] The module _winreg is whitelisted for local dev only. If your application relies on _winreg, it is likely that it will not function properly in production.
WARNING  2017-12-08 14:21:56,190 urlfetch_stub.py:551] Stripped prohibited headers from URLFetch request: ['Host']
ERROR    2017-12-08 19:21:57,332 webapp2.py:1528] [Errno 30] Read-only file system: 'image0.jpg'
Traceback (most recent call last):
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1511, in __call__
    rv = self.handle_exception(request, response, e)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1505, in __call__
    rv = self.router.dispatch(request, response)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1253, in default_dispatcher
    return route.handler_adapter(request, response)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1077, in __call__
    return handler.dispatch()
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 547, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "C:\MyMiniGCPProjects\FPDF\main.py", line 23, in get
    with open('image'+str(i)+'.jpg','wb') as output:
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\tools\devappserver2\python\runtime\stubs.py", line 278, in __init__
    raise IOError(errno.EROFS, 'Read-only file system', filename)
IOError: [Errno 30] Read-only file system: 'image0.jpg'
ERROR    2017-12-08 19:21:57,339 wsgi.py:279]
Traceback (most recent call last):
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\runtime\wsgi.py", line 267, in Handle
    result = handler(dict(self._environ), self._StartResponse)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1519, in __call__
    response = self._internal_error(e)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1511, in __call__
    rv = self.handle_exception(request, response, e)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1505, in __call__
    rv = self.router.dispatch(request, response)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1253, in default_dispatcher
    return route.handler_adapter(request, response)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 1077, in __call__
    return handler.dispatch()
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 547, in dispatch
    return self.handle_exception(e, self.app.debug)
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\lib\webapp2-2.3\webapp2.py", line 545, in dispatch
    return method(*args, **kwargs)
  File "C:\MyMiniGCPProjects\FPDF\main.py", line 23, in get
    with open('image'+str(i)+'.jpg','wb') as output:
  File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\tools\devappserver2\python\runtime\stubs.py", line 278, in __init__
    raise IOError(errno.EROFS, 'Read-only file system', filename)
IOError: [Errno 30] Read-only file system: 'image0.jpg'

我找不到任何有效的解决方案。 是否可以直接使用Cloud Storage中的文件并将PDF保存到Cloud Storage中？

Answer 1

您遇到了沙箱限制之一。 在沙箱中 ：

App Engine应用程序不能：

• 写入文件系统。 应用程序必须使用Cloud Datastore来存储持久性数据。 允许从文件系统读取，并且随应用程序上载的所有应用程序文件均可用。

好吧，关于数据存储的说明实际上是令人误解的，有几种存储选项，最适合您的情况是IMHO云存储（GCS）。

但是您不能使用常规的open()将文件写入GCS，而需要使用GCS客户端库。 您可以在此处找到一个示例： 编写CSV以存储在Google Cloud Storage中