#!/usr/bin/env bash
#
# Script to give information about zpools and zfs datasets
# Author: Brian Candler <b.candler@pobox.com>
#
# NOTE: zpool metrics requires zpool list -p
# (zfsonlinux 0.7.5 OK, 0.6.5.6 not OK)

set -eu

# which dataset types to show
DATASET_TYPES="filesystem,volume"
# metric name prefixes
ZPOOL="zfs_zpool"
DATASET="zfs_dataset"
# label names
ZPOOL_NAME="zpool_name"
DATASET_NAME="dataset_name"
DATASET_TYPE="dataset_type"

IFS=$'\t'

### zpool metadata ###

echo "# HELP ${ZPOOL} Constant metric with metadata about the zpool"
echo "# TYPE ${ZPOOL} gauge"
zpool list -H -o name,health,version,readonly,ashift,autoreplace,failmode |
while read -r name health version readonly ashift autoreplace failmode; do
  echo "${ZPOOL}{${ZPOOL_NAME}=\"$name\",health=\"$health\",version=\"$version\",readonly=\"$readonly\",ashift=\"$ashift\",autoreplace=\"$autoreplace\",failmode=\"$failmode\"} 1"
done

### zpool metrics ###

zpool_info="$(zpool list -Hp -o name,size,free,freeing,dedupratio,fragmentation 2>/dev/null)" &&
[ -n "$zpool_info" ] &&
while read -r col metric help; do
  echo "# HELP ${ZPOOL}_${metric} ${help}"
  echo "# TYPE ${ZPOOL}_${metric} gauge"
  while read -r -a line; do
    echo "${ZPOOL}_${metric}{${ZPOOL_NAME}=\"${line[0]}\"} ${line[$col]/%-/0}"
  done <<<"$zpool_info"
done <<<$'1\tsize_bytes\tTotal size of the storage pool
2\tfree_bytes\tThe amount of free space available in the pool
3\tfreeing_bytes\tThe amount of space waiting to be reclaimed from destroyed filesystems or snapshots
4\tdedupratio\tThe deduplication ratio
5\tfragmentation\tThe amount of fragmentation in the pool'

### dataset metadata ###

echo "# HELP ${DATASET} Constant metric with metadata about the zfs dataset"
echo "# TYPE ${DATASET} gauge"
zfs list -Hp -t $DATASET_TYPES -o name,type,creation,mounted,mountpoint,checksum,compression,readonly,version,dedup,volblocksize |
while read -r name type creation mounted mountpoint checksum compression readonly version dedup volblocksize; do
  echo "${DATASET}{$DATASET_NAME=\"$name\",$DATASET_TYPE=\"$type\",creation=\"$creation\",mounted=\"$mounted\",mountpoint=\"$mountpoint\",checksum=\"$checksum\",compression=\"$compression\",readonly=\"$readonly\",version=\"$version\",dedup=\"$dedup\",volblocksize=\"$volblocksize\"} 1"
done

### dataset metrics ###

dataset_info="$(zfs list -Hp -t $DATASET_TYPES -o name,used,available,referenced,compressratio,reservation,refreservation,volsize)" &&
[ -n "$dataset_info" ] &&
while read -r col metric help; do
  echo "# HELP ${DATASET}_${metric} ${help}"
  echo "# TYPE ${DATASET}_${metric} gauge"
  while read -r -a line; do
    # change "-" to "0", and "1.43x" to "1.430"
    echo "${DATASET}_${metric}{${DATASET_NAME}=\"${line[0]}\"} ${line[$col]/%[x-]/0}"
  done <<<"$dataset_info"
done <<<$'1\tused_bytes\tThe amount of space consumed by this dataset and all its descendents
2\tavailable_bytes\tThe amount of space available to the dataset and all its children
3\treferenced_bytes\tThe amount of data that is accessible by this dataset, which may or may not be shared with other datasets in the pool
4\tcompressratio\tFor non-snapshots, the compression ratio achieved for the used space of this dataset, expressed as a multiplier
5\treservation_bytes\tThe minimum amount of space guaranteed to a dataset and its descendants
6\trefreservation_bytes\tThe minimum amount of space guaranteed to a dataset, not including its descendents
7\tvolsize_bytes\tFor volumes, specifies the logical size of the volume'