#!/usr/bin/env bash
#
# script to recursively snapshot all zpools
#
# Author: Dave Eddy <dave@daveeddy.com>
# Date: November 20, 2015
# License: MIT

VERSION='v1.0.0'

usage() {
	local prog=${0##*/}
	cat <<-EOF
	usage: $prog [-hnx] <name> [[pool1] pool2 ...]

	recursively snapshot all zpools

	examples
	    # $prog foo
	    snapshot all zpools with the prefix foo

	    # $prog bar pool1 pool2
	    snapshot zpools pool1 and pool2 with the prefix bar

	    # $prog -x baz pool3
	    snapshot zpool pool3 with the *exact* snapshot name 'baz'


	options
	    -h             print this message and exit
	    -n             dry-run, don't actually create snapshots
	    -x             don't automatically append the date in epoch to
	                   the snapshot name
	    -V             print the version number and exit
	EOF
}

dryrun=false
date=true
while getopts 'hnxV' option; do
	case "$option" in
		h) usage; exit 0;;
		n) dryrun=true;;
		x) date=false;;
		V) echo "$VERSION"; exit 0;;
		*) usage; exit 1;;
	esac
done
shift "$((OPTIND - 1))"

# prefix to use for snapshots
name=$1
if [[ -z $name ]]; then
	echo 'error: name must be specified as the first argument' >&2
	exit 1
fi

# optional list of pools
shift
pools=("$@")
if (( ${#pools[@]} == 0 )); then
	# argument list was empty, use all pools
	while read -r zpool; do
		pools+=("$zpool")
	done < <(zpool list -Ho name)
fi

now=$(date +%s)
code=0
for zpool in "${pools[@]}"; do
	if $date; then
		snapshot=${zpool}@${name}_${now}
	else
		snapshot=${zpool}@${name}
	fi

	echo -n "zfs snapshot -r $snapshot"
	if $dryrun; then
		echo ' # dry-run: no action taken'
	else
		echo
		zfs snapshot -r "$snapshot" || code=1
	fi
done
exit "$code"