Disallowing public access to ISO uploads
I'm uploading ISO files to Vultr via the API. It's not problematic. The server hosts the ISO for a few minutes, waits for Vultr to finish downloading, and once it's confirmed that Vultr has the image, the server is destroyed.
However, during the time the image is being uploaded to Vultr, the ISO is available to the whole public. It is necessary to make the ISO public so that Vultr can access it. But this is not ideal.
Is there a better way to make the upload process more secure? Perhaps by providing Vultr's IP addresses that we can whitelist, allowing only Vultr to download the image but nobody else.