How to zip or tar a static folder without writing anything to the filesystem in python?

Question

I know about this question. But you can’t write to filesystem in app engine (shutil or zipfile require creating files).

So basically I need to archive something like/base/naclusing zip or tar, and write the output to the web browser asking the page (the output will never exceed 32 Mb).

Answer 1

It just happened that I had to solve the exact same problem tonight :) This worked for me:

    import StringIO
    import tarfile

    fd = StringIO.StringIO()

    with tarfile.open(mode="w:gz", fileobj=fd) as tgz:
        tgz.add('dir_to_download')

    self.response.headers['Content-Type'] ='application/octet-stream'
    self.response.headers['Content-Disposition'] = 'attachment; filename="archive.tgz"'

    self.response.write(fd.getvalue())

Key points:

• used StringIO to fake a file in memory
• used fileobj to pass directly the fake file's object to tarfile.open() (also supported by gzip.GzipFile() if you prefer gzip instead of tarfile)
• set headers to present the response as a downloadable file