#!/bin/bash
#
# Assumptions:
#
#  1]  we're on aws
#  2]  any ephemeral devices are ours to take
#  3]  if no ephemeral devices are available then there's a list
#      of hard-coded block devices to use for the splunk hot VG
#
#--------------------------------------------------------------------
exec > /dev/console
exec 2>&1

HOT_VG_NAME="vg_splunkhot"
HOT_LV_NAME="lv_splunkhot"

# These are the *HARD-CODED* volumes that we will use when no
# ephemeral disks are available
HOT_EBS_VOLUMES="xvdg xvdh"

IMDS2_TOKEN=$( curl --silent --fail -X PUT --connect-timeout 1 --max-time 2 'http://169.254.169.254/latest/api/token' -H 'X-aws-ec2-metadata-token-ttl-seconds: 90' )
CURL="curl -f --connect-timeout 1 -silent"
declare -A EBSMAP

# Yes heavy assumption we're on AWS
INSTANCE_TYPE="`${CURL} -H X-aws-ec2-metadata-token:\ ${IMDS2_TOKEN} http://169.254.169.254/latest/meta-data/instance-type`"
if [[ "$INSTANCE_TYPE" == "" ]]; then
	echo "Could not figure out instance type, giving up"
	exit 1
fi

# Build a map of EBS NVMe disks from their AWS-API-name to their NVMe name
# this makes an associative array (like a python hash) of the 
# sdX/xvdX name you'd set in AWS API to the corresponding nvmeX name
# Thanks Fred for the awesome id-ctrl stuff I'd never seen before
#
# One interesting side effect observed:  the id-ctrl output is different when 
# volumes are attached at boot time (no /dev/) versus attached after the OS
# is started (includes /dev/)
function make_nve_ebs_map {
	for DEVICE in $( lsblk -d -o NAME,MODEL -n | egrep "Elastic Block Store" | awk '{ print $1 }' ); do
		UNDERLYING=$( nvme id-ctrl --raw-binary /dev/${DEVICE} 2>/dev/null | cut -c 3073-3104 | tr -d ' ' | sed "s#/dev/##" )

		EBSMAP[$UNDERLYING]=$DEVICE
		UNDERLYING2=$( echo $UNDERLYING | sed "s/sd/xvd/" )
		EBSMAP[$UNDERLYING2]=$DEVICE
	done
}


DEVS=""

# Look for ephemeral NVMe disks
EPHEMERAL_DISKS=$( lsblk -d -o NAME,SIZE,TYPE,MODEL,SERIAL | egrep "Amazon EC2 NVMe Instance Storage" | awk '{ print "/dev/"$1 }' )
if [[ "${EPHEMERAL_DISKS}" != "" ]]; then
	# We have some ephemeral disks lets use them
	# This is the happy path

	DEVS="${EPHEMERAL_DISKS}"
else

	# Looking for the hard-coded volumes above to come attached.  They 
	# could be attached immediately, or it could take a "couple of minutes"
	# as they are created and attached by terraform.  
	# Checking for both the normal attachment and the NVMe form


	for VOLUME in $HOT_EBS_VOLUMES; do
		DONE=0
		TRIES=0
		while [[ $DONE -ne 1 ]] && [[ $TRIES -lt 20 ]]; do
			echo "Looking for $VOLUME to come attached"
			make_nve_ebs_map

			#echo "------- current nvme/ebs map -------"
			#for K in "${!EBSMAP[@]}"; do echo $K  = ${EBSMAP[$K]} ; done
			#echo "------- end current nvme/ebs map -------"

			if [[ -b /dev/$VOLUME ]]; then
				DEVS="/dev/$VOLUME $DEVS"
				DONE=1
			elif [[ -b /dev/${EBSMAP[$VOLUME]} ]]; then
				DEVS="/dev/${EBSMAP[$VOLUME]} $DEVS"
				DONE=1
			else
				sleep 10
				TRIES=$(( $TRIES + 1 ))
			fi

		done
	done
fi


if [[ "$DEVS" == "" ]]; then
	echo "Failed to enumerate possible devices, oops"
	exit 1
fi


DEVCOUNT=`echo $DEVS | wc -w`


# See if the volume group already exists - if not let's make it
if ! vgs --noheadings ${HOT_VG_NAME} >/dev/null 2>&1; then
	echo "Making VG on devices ${DEVS}"
	vgcreate ${HOT_VG_NAME} ${DEVS}
fi

# See if the logical volume already exists - if not make it
# and also make the filesystem
if ! lvs --noheadings ${HOT_VG_NAME}/${HOT_LV_NAME} >/dev/null 2>&1; then
	echo "Making LV"

	lvcreate -l 100%FREE --stripes $DEVCOUNT --name ${HOT_LV_NAME} ${HOT_VG_NAME}
	mkfs -t ext4 /dev/${HOT_VG_NAME}/${HOT_LV_NAME}
fi

if ! egrep -q "/dev/${HOT_VG_NAME}/${HOT_LV_NAME}" /etc/fstab; then
	echo "Adding to fstab"
	echo "/dev/vg_splunkhot/lv_splunkhot /opt/splunkdata/hot ext4 nofail,noatime 0 0" >> /etc/fstab
fi

if [[ ! -d /opt/splunkdata/hot ]]; then
	echo "Creating mount directories"
	mkdir -p /opt/splunkdata/hot
fi

if ! mountpoint /opt/splunkdata/hot >/dev/null 2>&1; then
	echo "Mounting it"
	mount /opt/splunkdata/hot
fi

# Looking for splunk user, trying to fix up ownerships in case they got lost
# This commonly happens when an ephemeral storage box loses its ephemeral storage
# but everything else survives
if getent passwd splunk | egrep -q splunk; then
	echo "Changing ownership of /opt/splunkdata and /opt/splunkdata/hot"
	chown splunk:splunk /opt/splunkdata
	chown splunk:splunk /opt/splunkdata/hot
fi