#!/bin/sh
########################################################################
# Begin $rc_base/init.d/aws
########################################################################

. /etc/sysconfig/rc
. ${rc_functions}

# https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/identify_ec2_instances.html
running_on_ec2() {
	local uuid

	# Check if the hypervisor UUID starts with ec2
	if [ -r "/sys/hypervisor/uuid" ]; then
		uuid=$(</sys/hypervisor/uuid)

		[ "${uuid:0:3}" = "ec2" ] && return 0
	fi

	# Check if the DMI product UUID starts with EC2
	if [ -r "/sys/devices/virtual/dmi/id/product_uuid" ]; then
		uuid=$(</sys/devices/virtual/dmi/id/product_uuid)

		[ "${uuid:0:3}" = "EC2" ] && return 0
	fi

	# We are not running on AWS EC2
	return 1
}

case "${1}" in
	start)
		# Do nothing if we are not running on AWS EC2
		running_on_ec2 || exit 0

		# Find the first interface to use
		for i in /sys/class/net/red* /sys/class/net/eth* \
				/sys/class/net/*; do
			[ -d "${i}" ] || continue
			i=$(basename ${i})

			# Skip loopback
			[ "${i}" = "lo" ] && continue

			# Use whatever we have found
			intf="${i}"
			break
		done

		# Check if we found a network interface
		if [ ! -n "${intf}" ]; then
			echo_failure

			boot_mesg -n "Could not find a network interface" ${FAILURE}
			boot_mesg "" ${NORMAL}
		fi

		# Run a DHCP client and set up the system accordingly
		dhclient -sf /etc/rc.d/helper/aws-setup "${intf}"

		# End DHCP client immediately
		dhclient -sf /etc/rc.d/helper/aws-setup -r "${intf}" &>/dev/null

		# Rename network devices
		udevadm trigger --action="add" --subsystem-match="net"

		exit 0
		;;

	status)
		if running_on_ec2; then
			echo "This system is running on AWS EC2"
			exit 0
		else
			echo "This system is NOT running on AWS EC2"
			exit 1
		fi
		;;

	*)
		echo "Usage: ${0} {start|status}"
		exit 1
		;;
esac

# End $rc_base/init.d/aws