Use EC2 ephemeral drive as swap

set_ec2_ephemeral_drive.sh

#!/bin/bash

TGTDEV="/dev/xvdb"

# Umount/Cleanup
[[ $(grep -wc "$TGTDEV" /proc/mounts) -eq 1 ]] && { fuser -km $TGTDEV; umount -f ${TGTDEV} 2>/dev/null || { echo "Can't unmount ${TGTDEV}"; exit 1; } }
[[ -e "${TGTDEV}2" ]] && [[ $(grep -wc "${TGTDEV}2" /proc/mounts) -eq 1 ]] && { fuser -km "${TGTDEV}2"; { umount -f "${TGTDEV}2" 2>/dev/null || { echo "Can't unmount ${TGTDEV}2"; exit 1; } } }
[[ -e "${TGTDEV}1" ]] && { swapoff "${TGTDEV}1" 2>/dev/null || { echo "Can't remove swap on ${TGTDEV}1 device"; exit 1; } }

# Partition the ephemeral disk
sed -e 's/\s*\([\+0-9a-zA-Z]*\).*/\1/' << EOF | fdisk ${TGTDEV}
  o # clear the in memory partition table
  n # new partition
  p # primary partition
  1 # partition number 1
    # default - start at beginning of disk 
  +10G # 10GB swap partition
  n # new partition
  p # primary partition
  2 # partion number 2
    # default, start immediately after preceding partition
    # default, extend partition to end of disk
  t # change partition lable 
  1 # of the first partition
  82 # to swap
  p # print the in-memory partition table
  w # write the partition table
  q # done
EOF

# Inform the os about new partitions
partprobe -s $TGTDEV

# Make swap
mkswap -f -L SWAP "${TGTDEV}1"
swapon "${TGTDEV}1"
swapon -s

# Make the second partition
mkfs -t ext4 "${TGTDEV}2"

# Setup fstab
sed -i -e "/^[^#]/ s/\(^.*\/dev\/xvdb[[:space:]]\+.*$\)/#\1/" /etc/fstab

grep -c "${TGTDEV}2" /etc/fstab &&
sed -i '/^[^#]/ s/\(^.*\/dev\/xvdb2.*$\)/\/dev\/xvdb2 \/mnt	auto defaults,nobootwait,comment=cloudconfig 0 2/' /etc/fstab || 
cat << EOF >> /etc/fstab
${TGTDEV}2	/mnt	auto	defaults,nobootwait,comment=cloudconfig	0	2
EOF

grep -c "${TGTDEV}1" /etc/fstab &&
sed -i '/^[^#]/ s/\(^.*\/dev\/xvdb1.*$\)/\/dev\/xvdb1 none    swap    sw   0  0/' /etc/fstab || 
cat << EOF >> /etc/fstab
${TGTDEV}1	none    swap    sw              0       0
EOF

mount -a

exit 0