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).

score 1 · Accepted Answer · answered Aug 11 '16 at 06:21

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

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

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