Node-RED is a tool for wiring together hardware devices, APIs and online services in new and interesting ways. See www.nodered.org and flows.nodered.org
These files are downloaded by Unraids Docker Manager rather than being built manually, but here is the command to start it.
docker run -d --name nodered -p 1880:1880 --device=/dev/ttyACM0:/dev/ttyACM0 -v /etc/localtime:/etc/localtime:ro -v /mnt/user/docker/appdata/nodered:/data:rw spants/nodered
As you can see, the /data directory where flows are created are stored at /mnt/user/docker/appdata/nodered in my setup - change to suit your install. I am also passing the device ttyACM0 which is a USB to Serial device (actually a small radio receiver) to be used within the docker.