google_appengine/google/appengine/ext/zipserve/__init__.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2007 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17
  18 """Serve static files from a zipfile.
  19
  20 This is a solution for apps that want to serve 1000s of small static
  21 files while staying withing the 1000 file limit.
  22
  23 The simplest use case is driven purely from the handlers section in
  24 app.yaml, e.g.:
  25
  26   - url: /images/.*
  27     script: $PYTHON_LIB/google/appengine/ext/zipserve
  28
  29 This would invoke a main() within zipserve/__init__.py.  This code
  30 would then take the URL path, and look for a .zip file under the first
  31 component of the path, in this case "images.zip" in the app's working
  32 directory.  If found, it will then serve any matching paths below that
  33 from the zip file.  In other words, /images/foo/icon.gif would map to
  34 foo/icon.gif in the zip file images.zip.
  35
  36 You can also customize the behavior by adding a custom line to your
  37 WSGIApplication() invocation:
  38
  39   def main():
  40     app = webapp.WSGIApplication(
  41             [('/', MainPage),
  42              ('/static/(.*)', zipserve.make_zip_handler('staticfiles.zip')),
  43             ])
  44
  45 You can pass max_age=N to the make_zip_handler() call to override the
  46 expiration time in seconds, which defaults to 600.
  47
  48 To customize the behavior even more, you can subclass ZipHandler and
  49 override the get() method, or override it and call ServeFromZipFile()
  50 directly.
  51
  52 Note that by default, a Cache-control is added that makes these pages
  53 cacheable even if they require authentication.  If this is not what
  54 you want, override ZipHandler.SetCachingHeaders().
  55 """
  56
  57
  58 import email.Utils
  59 import logging
  60 import mimetypes
  61 import time
  62 import zipfile
  63
  64 from google.appengine.ext import webapp
  65 from google.appengine.ext.webapp import util
  66
  67
  68 def make_zip_handler(zipfilename, max_age=None, public=None):
  69   """Factory function to construct a custom ZipHandler instance.
  70
  71   Args:
  72     zipfilename: The filename of a zipfile.
  73     max_age: Optional expiration time; defaults to ZipHandler.MAX_AGE.
  74     public: Optional public flag; defaults to ZipHandler.PUBLIC.
  75
  76   Returns:
  77     A ZipHandler subclass.
  78   """
  79   class CustomZipHandler(ZipHandler):
  80     def get(self, name):
  81       self.ServeFromZipFile(self.ZIPFILENAME, name)
  82     ZIPFILENAME = zipfilename
  83     if max_age is not None:
  84       MAX_AGE = max_age
  85     if public is not None:
  86       PUBLIC = public
  87
  88   return CustomZipHandler
  89
  90
  91 class ZipHandler(webapp.RequestHandler):
  92   """Request handler serving static files from zipfiles."""
  93
  94   zipfile_cache = {}
  95
  96   def get(self, prefix, name):
  97     """GET request handler.
  98
  99     Typically the arguments are passed from the matching groups in the
 100     URL pattern passed to WSGIApplication().
 101
 102     Args:
 103       prefix: The zipfilename without the .zip suffix.
 104       name: The name within the zipfile.
 105     """
 106     self.ServeFromZipFile(prefix + '.zip', name)
 107
 108   def ServeFromZipFile(self, zipfilename, name):
 109     """Helper for the GET request handler.
 110
 111     This serves the contents of file 'name' from zipfile
 112     'zipfilename', logging a message and returning a 404 response if
 113     either the zipfile cannot be opened or the named file cannot be
 114     read from it.
 115
 116     Args:
 117       zipfilename: The name of the zipfile.
 118       name: The name within the zipfile.
 119     """
 120     zipfile_object = self.zipfile_cache.get(zipfilename)
 121     if zipfile_object is None:
 122       try:
 123         zipfile_object = zipfile.ZipFile(zipfilename)
 124       except (IOError, RuntimeError), err:
 125         logging.error('Can\'t open zipfile %s: %s', zipfilename, err)
 126         zipfile_object = ''
 127       self.zipfile_cache[zipfilename] = zipfile_object
 128     if zipfile_object == '':
 129       self.error(404)
 130       self.response.out.write('Not found')
 131       return
 132     try:
 133       data = zipfile_object.read(name)
 134     except (KeyError, RuntimeError), err:
 135       self.error(404)
 136       self.response.out.write('Not found')
 137       return
 138     content_type, encoding = mimetypes.guess_type(name)
 139     if content_type:
 140       self.response.headers['Content-Type'] = content_type
 141     self.SetCachingHeaders()
 142     self.response.out.write(data)
 143
 144   MAX_AGE = 600
 145
 146   PUBLIC = True
 147
 148   def SetCachingHeaders(self):
 149     """Helper to set the caching headers.
 150
 151     Override this to customize the headers beyond setting MAX_AGE.
 152     """
 153     max_age = self.MAX_AGE
 154     self.response.headers['Expires'] = email.Utils.formatdate(
 155         time.time() + max_age, usegmt=True)
 156     cache_control = []
 157     if self.PUBLIC:
 158       cache_control.append('public')
 159     cache_control.append('max-age=%d' % max_age)
 160     self.response.headers['Cache-Control'] = ', '.join(cache_control)
 161
 162
 163 def main():
 164   """Main program.
 165
 166   This is invoked when this package is referenced from app.yaml.
 167   """
 168   application = webapp.WSGIApplication([('/([^/]+)/(.*)', ZipHandler)])
 169   util.run_wsgi_app(application)
 170
 171
 172 if __name__ == '__main__':
 173   main()