How to get progress of file upload using requests.post() if the file was just uploaded via form-data? (Not sure whether this is a streaming process)

Suppose I'm running some kind of web service with python & flask aiming to provide file upload. It should be noted that my service is only a kind of transfer station, which means I'll "repost" the file elsewhere, say, a massive centralized file storage, as soon as I receive a file from frontend form-data. The flask code looks like this:

@admin.route('/data', methods=['POST'])
def data_upload():
    if 'file' in request.files:
        f = request.files['file']
        try:
            r = Requests.post(DataConfig.server + '/' + '/upload.php', files={'file': (f.filename, f)})
            return {'e': 0, 'msg': r.content.decode('utf-8')}
        except RequestException:
            return ReturnCode.ERR_NETWORK_FAILURE
    return ReturnCode.ERR_BAD_DATA

It is not allowed that the frontend directly send file or data to "upload.php", since the server key should not be exposed to users.

Now I've got two problems that confuse me.

• Is this process streaming or streaming-ready? I mean, whether my python server will receive the file and store it somewhere temporarily, or the file will be repost in chunks, like iter_block? If streaming is not readily enabled, how can I do so to enable large-file uploading user experience?
• Is it possible to provide the user (frontend, browser) information about the progress of uploading?

For question 2, there exists some posts indicating that tqdm will help, but tqdm is a cli tool and printing anything in the python server's terminal makes no sense, and document of tqdm doesn't show me any obvious reference about their apis to get a percentage. What's more, I think that maybe sending this percentage to frontend may require some xhr techniques, which I believe my code can't deal with.

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