def upload(self, filename, filedata=None, filepath=None, **kwargs):
        """Upload the specified file into the project.

        .. note::

            Either ``filedata`` or ``filepath`` *MUST* be specified.

        Args:
            filename (str): The name of the file being uploaded
            filedata (bytes): The raw data of the file being uploaded
            filepath (str): The path to a local file to upload (optional)

        Raises:
            GitlabConnectionError: If the server cannot be reached
            GitlabUploadError: If the file upload fails
            GitlabUploadError: If ``filedata`` and ``filepath`` are not
                specified
            GitlabUploadError: If both ``filedata`` and ``filepath`` are
                specified

        Returns:
            dict: A ``dict`` with the keys:
                * ``alt`` - The alternate text for the upload
                * ``url`` - The direct url to the uploaded file
                * ``markdown`` - Markdown for the uploaded file
        """
        if filepath is None and filedata is None:
            raise GitlabUploadError("No file contents or path specified")

        if filedata is not None and filepath is not None:
            raise GitlabUploadError("File contents and file path specified")

        if filepath is not None:
            with open(filepath, "rb") as f:
                filedata = f.read()

        url = ('/projects/%(id)s/uploads' % {
            'id': self.id,
        })
        file_info = {
            'file': (filename, filedata),
        }
        data = self.manager.gitlab.http_post(url, files=file_info)

        return {
            "alt": data['alt'],
            "url": data['url'],
            "markdown": data['markdown']
        }