Useful for automatically adding swap to hosts provisioned using tools such as tutum.co (it should also work with Docker Cloud).
On Tutum, set deployment strategy to "every node", and set privileged to "On". Set the deploy tags as needed. It also needs two volumes set to access files from the host: /etc/fstab, and /var/lib (or the parent directory of the swap file location set in the SWAPFILE environment variable). Set the SWAPSIZE environment variable to the size (in MB) of the swap file to use. When you deploy, then it will add a swap file to all the nodes that match the deploy tags, and when a new node is created, then a swap file will be created if it matches the deploy tags.