gistfile1.txt

create this file in your /root folder

$ fleetctl load swapon.service
$ fleetctl start swapon.service

This will create swap file on all nodes of your CoreOS cluster without prior setup.

See also http://cloudinit.readthedocs.org/en/latest/topics/examples.html#adjust-mount-points-mounted

swapon.service

[Unit]
Description=Turn on swap

[Service]
Type=oneshot
Environment="SWAPFILE=/4GiB.swap"
RemainAfterExit=true
ExecStartPre=/usr/bin/touch ${SWAPFILE}
ExecStartPre=/usr/bin/fallocate -l 4096m ${SWAPFILE}
ExecStartPre=/usr/bin/chmod 600 ${SWAPFILE}
ExecStartPre=/usr/sbin/mkswap ${SWAPFILE}
ExecStartPre=/usr/sbin/losetup -f ${SWAPFILE}
ExecStart=/usr/bin/sh -c "/sbin/swapon $(/usr/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"
ExecStop=/usr/bin/sh -c "/sbin/swapoff $(/usr/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"
ExecStopPost=/usr/bin/sh -c "/usr/sbin/losetup -d $(/usr/sbin/losetup -j ${SWAPFILE} | /usr/bin/cut -d : -f 1)"

[Install]
WantedBy=multi-user.target

[X-Fleet]
Global=true