proxmoxer only builds a multipart request for io.IOBase values passed
as kwargs; a plain filename string (plus a nonexistent "data" field,
as the old code sent) goes out as an ordinary form-urlencoded POST
instead. Real Proxmox's /storage/{s}/upload endpoint expects an actual
file upload for "filename" and responds to anything else by closing
the connection with no HTTP response at all.
Found live: the VM shell, disk import, and node-scoped storage
selection all succeeded, then create_vm_from_cloud_init failed with
requests.exceptions.ConnectionError / RemoteDisconnected right at the
snippet upload step.
Christian Manivong
80d9c7335f