Download a file without storing it - flask

Question

I'm building a Youtube Video Downloader using PyTube and Flask. What I want to do is the end user receives the video file, but I never store it into the server.
Currently the code looks like this:
def download_video():
if request.method == "POST":
url = YouTube(session['link']) # Getting user input
itag = request.form.get("itag") # Getting user input
video = url.streams.get_by_itag(itag)
file = video.download(path) # Downloading the video into a folder
return send_file(file, as_attachment=True)
return redirect(url_for("home"))
The code works fine, the only drawback is that it is being store into the server, which later on can become an issue.
I already tried to download it to /dev/null/, which locally seems to work, but when deployed to Heroku, it gives me an Internal Server Error.

Answer 1

The download method is used to:
Write the media stream to disk.
A dirty workaround could of course be to remove the file saved at the output_path after calling download, but you could also write the media stream to a buffer using stream_to_buffer and send that.
Minimal and reproducible example
from pytube import YouTube
from flask import Flask, send_file
from io import BytesIO
app = Flask(__name__)
#app.route("/")
def index():
buffer = BytesIO()
url = YouTube("https://www.youtube.com/watch?v=dQw4w9WgXcQ")
video = url.streams.get_by_itag(18)
video.stream_to_buffer(buffer)
buffer.seek(0)
return send_file(
buffer,
as_attachment=True,
attachment_filename="cool-video.mp4",
mimetype="video/mp4",
)
if __name__ == "__main__":
app.run()