gistfile1.txt

#!/bin/bash

set -e
set -x

read -r -d '' attach_eth1_eni <<'EOF'
#!/bin/bash

function log () {
  echo "$(date +"%b %e %T") $@"
  logger -- $(basename $0) " - $@"
}

instance_id=$(curl -s http://169.254.169.254/latest/meta-data/instance-id)
eni_id=$(cat /var/tmp/eni-id.txt)
/usr/bin/aws ec2 attach-network-interface --network-interface-id $${eni_id} --instance-id $${instance_id} --device-index 1

retcode=$?

[ "$retcode" -eq 0 ] && { log "eni attachment successful" ; exit 0 ; } || { log "eni attachment failed" ; exit 1 ; }

EOF


echo "Attaching elastic interface"
echo "${attach_eth1_eni}" > /usr/local/bin/attach_eth1_eni.sh
chmod 755 /usr/local/bin/attach_eth1_eni.sh
echo ${eni} > /var/tmp/eni-id.txt

export AWS_DEFAULT_REGION="${aws_region}"
/usr/local/bin/attach_eth1_eni.sh

sleep 60

echo "Dropping eth0"
# This is necessary otherwise there are identical routes to the public subnet via two separate interfaces!
ifdown eth0
echo "Configuring NAT forwarding"
iptables -t nat -A POSTROUTING -j MASQUERADE
iptables -A FORWARD -j ACCEPT
echo 1 > /proc/sys/net/ipv4/ip_forward