attach-ebs

attach-ebs

#! /bin/bash

USERDATA=`ec2metadata --user-data`
AVAILABILITY_ZONE=`ec2metadata --availability-zone`
INSTANCE_ID=`ec2metadata --instance-id`
SPLIT_CHAR="|"

attach_volume() {  # $1=instance Id, $2=device path, $3=volume Id
	echo "Attaching volume $3 to instance $1 on path $2"

	ATTACH_RESULT=`euca-attach-volume $3 -i $1 -d $2`
	sleep 5
	echo $ATTACH_RESULT
}

find_snapshot() {
	echo "Finding snapshot for ${EBS_PARAMS[0]} on path ${EBS_PARAMS[3]}..."

	SNAPSHOT_DETAILS=`euca-describe-snapshots --filter "tag:Name=${EBS_PARAMS[0]}" --filter "tag:Device=${EBS_PARAMS[3]}" --filter "status=completed" `
	SNAPSHOT_ID=`echo $SNAPSHOT_DETAILS | awk '{print $2}'`
	if [ $SNAPSHOT_ID != "" ]; then
		echo "Found $SNAPSHOT_ID - creating a volume from it..."
		make_volume_from_snapshot $SNAPSHOT_ID
	else
		echo "Hmm, no snapshots can be found to match the user-data!  Skipping to next EBS..."
	fi
}

make_volume_from_snapshot() { # $1=snapshot id
	echo "Making ${EBS_PARAMS[2]}GB volume from snapshot $1 in $AVAILABILITY_ZONE"
	VOLUME_DETAILS=`euca-create-volume --size ${EBS_PARAMS[2]} --snapshot $1 -z $AVAILABILITY_ZONE` 
	VOLUME_ID=`echo $VOLUME_DETAILS | awk '{print $2}'`
	AVAILABLE=`euca-describe-volumes $VOLUME_ID | grep available`
	  until [ -n "$AVAILABLE" ]; do
	  echo "waiting..."
	  sleep 5
	  AVAILABLE=`euca-describe-volumes $VOLUME_ID | grep available`
	  done
	echo "Volume $VOLUME_ID created!"
	echo `euca-create-tags $VOLUME_ID --tag Name=${EBS_PARAMS[0]} --tag Device=${EBS_PARAMS[3]}`
	attach_volume $INSTANCE_ID ${EBS_PARAMS[3]} $VOLUME_ID
}

echo "Going to attach some EBS volumes in $AVAILABILITY_ZONE..."

if [[ $USERDATA == *$SPLIT_CHAR* ]]; then

	saveIFS=$IFS
	IFS=$SPLIT_CHAR
	PARAMS=($USERDATA)
	IFS=$saveIFS

	declare -A USERDATA_KEYVALUE
	for ((i=0; i<${#PARAMS[@]}-1; i+=2))
	do
	    USERDATA_KEYVALUE[${PARAMS[i]}]=${PARAMS[i+1]}
	done

	for i in {1..4}
	do
		if [[ -n "${USERDATA_KEYVALUE[EBS${i}]}" ]]; then
			echo "Current EBS volume is ${i}: user-data is ${USERDATA_KEYVALUE[EBS${i}]}"

			saveIFS=$IFS
			IFS=","
			EBS_PARAMS=(${USERDATA_KEYVALUE[EBS${i}]})
			IFS=$saveIFS

			CHECK_ATTACHED=`euca-describe-volumes --filter "attachment.instance-id=$INSTANCE_ID" --filter "attachment.device=${EBS_PARAMS[3]}"`
			ALREADY_ATTACHED=`echo $CHECK_ATTACHED | awk '{print $2}'`
			if [[ $ALREADY_ATTACHED != "" ]]; then
				echo "It looks like $ALREADY_ATTACHED is mounted to $INSTANCE_ID on ${EBS_PARAMS[3]} already; skipping to next EBS..."
			else
				case ${EBS_PARAMS[1]} in
		        attach)
					VOLUME_DETAILS=`euca-describe-volumes --filter "tag:Name=${EBS_PARAMS[0]}" --filter "tag:Device=${EBS_PARAMS[3]}" --filter "availability-zone=$AVAILABILITY_ZONE"`
					VOLUME_ID=`echo $VOLUME_DETAILS | awk '{print $2}'`
					if [[ $VOLUME_DETAILS == *available* ]]; then
						echo "Volume $VOLUME_ID is available, attaching..."
						attach_volume $INSTANCE_ID ${EBS_PARAMS[3]} $VOLUME_ID
					else
						echo "There doesn't seem to be a matching EBS volume available in this availability zone.  Trying to find a snapshot instead..."
						find_snapshot ${EBS_PARAMS[0]} ${EBS_PARAMS[3]}
					fi
	                break
	                ;;
				snapshot)
					find_snapshot 
					break
					;;
				create)
					echo "Making ${EBS_PARAMS[2]}GB volume in $AVAILABILITY_ZONE"
					VOLUME_DETAILS=`euca-create-volume --size ${EBS_PARAMS[2]} -z $AVAILABILITY_ZONE` 
					VOLUME_ID=`echo $VOLUME_DETAILS | awk '{print $2}'`
					AVAILABLE=`euca-describe-volumes $VOLUME_ID | grep available`
					  until [ -n "$AVAILABLE" ]; do
					  echo "waiting..."
					  sleep 5
					  AVAILABLE=`euca-describe-volumes $VOLUME_ID | grep available`
					  done
					echo "Volume $VOLUME_ID created!"
					echo `euca-create-tags $VOLUME_ID --tag Name=${EBS_PARAMS[0]} --tag Device=${EBS_PARAMS[3]}`
					attach_volume $INSTANCE_ID ${EBS_PARAMS[3]} $VOLUME_ID
					break
					;;
	        	*)      
	                echo "action is unknown.. is the user-data correct?"
	                exit 1 
	                ;;
	            esac 
	        fi
		fi
	done
	echo "All EBS volumes in user-data have been processed."
else
	echo "Hmm, there doesn't seem to be any user-data.  Nothing to do."
fi