Support optional BOTO specification with --no_auth.

download_from_google_storage.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Download files from Google Storage based on SHA1 sums."""
 
 
 import hashlib
 import optparse
@@ skipping 366 matching lines @@
     if options.auto_platform:
       parser.error('--platform can not be specified with --auto_platform')
     if not re.match(options.platform, GetNormalizedPlatform()):
       if options.verbose:
         print('The current platform doesn\'t match "%s", skipping.' %
               options.platform)
       return 0
 
   # Set the boto file to /dev/null if we don't need auth.
   if options.no_auth:
-    options.boto = os.devnull
+    if (set(('http_proxy', 'https_proxy')).intersection(
+        env.lower() for env in os.environ) and
+        'NO_AUTH_BOTO_CONFIG' not in os.environ):
+      print >> sys.stderr, ('NOTICE: You have PROXY values set in your '
+                            'environment, but gsutil in depot_tools does not '
+                            '(yet) obey them.')
+      print >> sys.stderr, ('Also, --no_auth prevents the normal BOTO_CONFIG '
+                            'environment variable from being used.')
+      print >> sys.stderr, ('To use a proxy in this situation, please supply '
+                            'those settings in a .boto file pointed to by '
+                            'the NO_AUTH_BOTO_CONFIG environment var.')
+    options.boto = os.environ.get('NO_AUTH_BOTO_CONFIG', os.devnull)
 
   # Make sure gsutil exists where we expect it to.
   if os.path.exists(GSUTIL_DEFAULT_PATH):
     gsutil = Gsutil(GSUTIL_DEFAULT_PATH,
                     boto_path=options.boto)
   else:
     parser.error('gsutil not found in %s, bad depot_tools checkout?' %
                  GSUTIL_DEFAULT_PATH)
 
   # Passing in -g/--config will run our copy of GSUtil, then quit.
@@ skipping 52 matching lines @@
       return code
 
   return download_from_google_storage(
       input_filename, base_url, gsutil, options.num_threads, options.directory,
       options.recursive, options.force, options.output, options.ignore_errors,
       options.sha1_file, options.verbose, options.auto_platform)
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))