Writing files to Dropbox account from GAE

Question

I am trying to create files in a Dropbox.com folder from a GAE application. I have done all the steps the register a Dropbox application and installed the Python SDK from Dropbox locally on my development machine. (see dropbox.com API). It all works perfectly when I use the cli_client.py test script in the dropbox SDK on my local machine to access dropbox - can 'put' files etc.

I now want to start working in GAE environment, so things get a bit tricky. Some help would be useful.

For those familiar with the Dropbox API code, I had the following issues thus far:

Issue 1

The rest.py Dropbox API module uses pkg_resources to get the certs installed in site-packages of a local machine installation. I replaced

TRUSTED_CERT_FILE = pkg_resources.resource_filename(__name__, 'trusted-certs.crt')

with

TRUSTED_CERT_FILE = file('trusted-certs.crt')

and placed the cert file in my GAE application directory. Perhaps this is not quite right; see my authentication error code below.

Issue 2

The session.py Dropbox API module uses oauth module, so I changed the include to appengine oauth.

But raised an exception that GAE's oauth does not have OAuthConsumer method used by the Dropbox session.py module. So i downloaded oauth 1.0 and added to my application an now import this instead of GAE oauth.

Issue 3

GAE ssl module does not seem to have CERT_REQUIRED property.

This is a constant, so I changed

self.cert_reqs = ssl.CERT_REQUIRED

to

self.cert_reqs = 2

This is used when calling

ssl.wrap_socket(sock, cert_reqs=self.cert_reqs, ca_certs=self.ca_certs)

Authentication Error

But I still can't connect to Dropbox:

Status: 401
Reason: Unauthorized
Body: {"error": "Authentication failed"}
Headers: [('date', 'Sun, 19 Feb 2012 15:11:12 GMT'), ('transfer-encoding', 'chunked'), ('connection', 'keep-alive'), ('content-type', 'application/json'), ('server', 'dbws')]

Answer 1

Here's my patched version of Dropbox Python SDK 1.4 which works well for me with Python 2.7 GAE: dropbox_python_sdk_gae_patched.7z.base64. No extra third-party libraries needed, only those provided by GAE environment.

Only file uploading (put_file) is tested. Here're setup steps:

1. Unpack archive to the root folder of GAE application (if main app is in the root folder). You can decode BASE64 using Base64 Encoder/Decoder: base64.exe -d dropbox_python_sdk_gae_patched.7z.base64 dropbox_python_sdk_gae_patched.7z.
2. Setup APP_KEY, APP_SECRET, ACCESS_TYPE, ACCESS_TOKEN_KEY, ACCESS_TOKEN_SECRET. First three are configured at dropbox application creation time. Last two are obtained when granting application access to specific dropbox account, you can get them through cli_client.py (from DB Python SDK) from token_store.txt file.

3. Use in the code like this:

   import dropbox
   # ...
   def DropboxUpload(path, data):
       sess = dropbox.session.DropboxSession(APP_KEY, APP_SECRET, ACCESS_TYPE)
       sess.set_token(ACCESS_TOKEN_KEY, ACCESS_TOKEN_SECRET)
       cli = dropbox.client.DropboxClient(sess)
       data_file = StringIO.StringIO(data)
       return cli.put_file(path, data_file)
   # ...
   import json
   class DropboxUploadHandlerExample(webapp2.RequestHandler):
       def get(self):
           url = "http://www.google.com/"
           result = urlfetch.fetch(url)
           self.response.headers['Content-Type'] = 'application/json'
           self.response.out.write(json.dumps(DropboxUpload('/fetch_result.dat', result.content)))