you can send files to your server without opening some random port or using a docker container or something very easily, over ssh using scp.
for this blog i am using prose.sh, i send my markdown files to them using scp:
1scp ~/dev/blog/*.md firstname.lastname@example.org:/
or sending images to my server, or a backup:
1scp ~/pix snowflake:/mnt/raid/pix/
1scp "/mnt/usb1/backup-$(date).tar.gz" snowflake:/mnt/raid/backups/
snowflakeworks here, since i have some details about
1: dont need to open another port 2: can use very secure ssh keys 3: dont have to depend on sluggish web apps 4: can use it almost everywhere: bsd, mac, (gnu/)linux and windows, all of those support ssh/scp.