[Unit]
Description=Subscriptions Port 80 to 443 Redirect
After=network.target

[Service]
# Set the domain of your instance here:
Environment=DOMAIN=subscriptions.gir.st

Type=simple
ExecStart=/usr/bin/nc -lkc 'read method path http; printf "HTTP/1.1 308 Moved\r\nLocation: https://${DOMAIN}%%s\r\n\r\n" "$path"' 80
Restart=always  # NOTE^: must to escape % in ExecStart, or systemd replaces %s with $SHELL

[Install]
WantedBy=multi-user.target