Feb 25, 2020

scripts/zfs-prune-snapshots

@@ -0,0 +1,172 @@
+#!/usr/bin/env bash
+#
+# script to prune zfs snapshots over a given age
+#
+# Author: Dave Eddy <dave@daveeddy.com>
+# Date: November 20, 2015
+# License: MIT
+
+VERSION='v1.0.1'
+
+usage() {
+	local prog=${0##*/}
+	cat <<-EOF
+	usage: $prog [-hnv] [-p <prefix] <time> [[dataset1] ...]
+
+	remove snapshots from one or more zpools that match given criteria
+
+	examples
+	    # $prog 1w
+	    remove snapshots older than a week across all zpools
+
+	    # $prog -vn 1w
+	    same as above, but with increased verbosity and without
+	    actually deleting any snapshots (dry-run)
+
+	    # $prog 3w tank1 tank2/backup
+	    remove snapshots older than 3 weeks on tank1 and tank2/backup.
+	    note that this script will recurse through *all* of tank1 and
+	    *all* datasets below tank2/backup
+
+	    # $prog -p 'autosnap_' 1M zones
+	    remove snapshots older than a month on the zones pool that start
+	    with the string "autosnap_"
+
+	timespec
+	    the first argument denotes how old a snapshot must be for it to
+	    be considered for deletion - possible specifiers are
+
+	        s seconds
+	        m minutes
+	        h hours
+	        d days
+	        w weeks
+	        M months
+	        y years
+
+	options
+	    -h             print this message and exit
+	    -n             dry-run, don't actually delete snapshots
+	    -p <prefix>    snapshot prefix string to match
+	    -q             quiet, do not printout removed snapshots
+	    -v             increase verbosity
+	    -V             print the version number and exit
+	EOF
+}
+
+debug() {
+	((verbosity >= 1)) && echo "$@"
+	return 0
+}
+
+# given a time in seconds, return the "human readable" string
+human() {
+	local seconds=$1
+	if ((seconds < 0)); then
+		((seconds *= -1))
+	fi
+
+	local times=(
+	$((seconds / 60 / 60 / 24 / 365)) # years
+	$((seconds / 60 / 60 / 24 / 30))  # months
+	$((seconds / 60 / 60 / 24 / 7))   # weeks
+	$((seconds / 60 / 60 / 24))       # days
+	$((seconds / 60 / 60))            # hours
+	$((seconds / 60))                 # minutes
+	$((seconds))                      # seconds
+	)
+	local names=(year month week day hour minute second)
+
+	local i
+	for ((i = 0; i < ${#names[@]}; i++)); do
+		if ((${times[$i]} > 1)); then
+			echo "${times[$i]} ${names[$i]}s"
+			return
+		elif ((${times[$i]} == 1)); then
+			echo "${times[$i]} ${names[$i]}"
+			return
+		fi
+	done
+	echo '0 seconds'
+}
+
+dryrun=false
+verbosity=0
+prefix=
+quiet=false
+while getopts 'hnqp:vV' option; do
+	case "$option" in
+		h) usage; exit 0;;
+		n) dryrun=true;;
+		p) prefix=$OPTARG;;
+		q) quiet=true;;
+		v) ((verbosity++));;
+		V) echo "$VERSION"; exit 0;;
+		*) usage; exit 1;;
+	esac
+done
+shift "$((OPTIND - 1))"
+
+# extract the first argument - the timespec - and
+# convert it to seconds
+t=$1
+time_re='^([0-9]+)([smhdwMy])$'
+seconds=
+if [[ $t =~ $time_re ]]; then
+	# ex: "21d" becomes num=21 spec=d
+	num=${BASH_REMATCH[1]}
+	spec=${BASH_REMATCH[2]}
+
+	case "$spec" in
+		s) seconds=$((num));;
+		m) seconds=$((num * 60));;
+		h) seconds=$((num * 60 * 60));;
+		d) seconds=$((num * 60 * 60 * 24));;
+		w) seconds=$((num * 60 * 60 * 24 * 7));;
+		M) seconds=$((num * 60 * 60 * 24 * 30));;
+		y) seconds=$((num * 60 * 60 * 24 * 365));;
+		*) echo "error: unknown spec '$spec'" >&2; exit 1;;
+	esac
+elif [[ -z $t ]]; then
+	echo 'error: timespec must be specified as the first argument' >&2
+	exit 1
+else
+	echo "error: failed to parse timespec '$t'" >&2
+	exit 1
+fi
+
+shift
+pools=("$@")
+
+now=$(date +%s)
+code=0
+while read -r creation snapshot; do
+	# ensure optional prefix matches
+	snapname=${snapshot#*@}
+	if [[ -n $prefix && $prefix != "${snapname:0:${#prefix}}" ]]; then
+		debug "skipping $snapshot: doesn't match prefix $prefix"
+		continue
+	fi
+
+	# ensure snapshot is older than the cutoff time
+	delta=$((now - creation))
+	human=$(human "$delta")
+	if ((delta <= seconds)); then
+		debug "skipping $snapshot: $human old"
+		continue
+	fi
+
+	# remove the snapshot
+	if ! $quiet || $dryrun; then
+		echo -n "removing $snapshot: $human old"
+	fi
+	if $dryrun; then
+		echo ' <dry-run: no action taken>'
+	else
+		if ! $quiet; then
+			echo
+		fi
+		zfs destroy "$snapshot" || code=1
+	fi
+done < <(zfs list -Hpo creation,name -t snapshot -r "${pools[@]}")
+exit "$code"