bashclub-zfs-push-pull/backup-zfs

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#!/bin/bash
# backup-zfs: use zfs send/recv to push/pull snapshots
prog="$(basename "$0")"
usage() {
echo "$(basename "$0") [-hvq] [-t tag] [-k keep] [-d dateopts] [srchost:]srcfs [desthost:]destfs" >&2
echo "$(basename "$0"): use zfs send/recv to push/pull snapshots" >&2
printf "%15s: %s\n" >&2 "-h" "this help statement" \
"-v" "verbose" \
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"-q" "quiet" \
"-t tag" "tag to use for naming snapshots and in syslog" \
"-k keep" "number of snapshots to keep on src" \
"-d dateopts" "options string for date(1), used in naming snapshots"
exit $1
}
# log to syslog; if verbose or on a tty, also to stdout
# usage: log msg
log() {
logger -t "$prog" -- "$@"
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if ! $quiet && [[ -t 1 ]] || $verbose ; then
echo "$@" >&2
fi
}
# exit with a code & message
# usage: die $exitcode msg
die() {
code="$1"
shift
if [[ $code -ne 0 ]] ; then
verbose=true log "FATAL: $@"
else
log "$@"
fi
exit $code
}
# run zfs(1) command either locally or via ssh
# usage: ZFS "$host" command args...
ZFS() {
host="$1"
shift
if [[ -n $host ]] ; then
log "remote ($host): zfs $@"
ssh "$host" sudo zfs "$@"
else
log "local: zfs $@"
sudo zfs "$@"
fi
}
###
### defaults
###
tag="$prog"
dateopts="+%F_%T"
keep=5
verbose=false
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quiet=false
###
### parse options
###
while getopts "hvqk:t:d:" opt ; do
case $opt in
h) usage 0 ;;
v) verbose=true ;;
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q) quiet=true ;;
k) keep=$OPTARG ;;
t) tag=$OPTARG ;;
d) dateopts=$OPTARG ;;
*) usage 1 ;;
esac
done
shift $((OPTIND-1))
date="$(date $dateopts)"
###
### parse src & dest host/fs info
###
# fail if there's ever >1 colon
if [[ $1 =~ :.*: || $2 =~ :.*: ]] ; then
die 1 "invalid fsspec: '$1' or '$2'"
fi
# fail if src or dest isn't specified
if [[ -z $1 || -z $2 ]] ; then
usage 1
fi
src="$1"
dest="$2"
# discard anything before a colon to get the fs
srcfs="${src#*:}"
destfs="${dest#*:}"
# iff there is a colon, discard everything after it to get the host
[[ $src =~ : ]] && srchost="${src%:*}"
[[ $dest =~ : ]] && desthost="${dest%:*}"
# get the last src component
srcbase="${srcfs##*/}"
###
### create new snapshot on src
###
cur="$srcfs@${tag}_$date"
ZFS "$srchost" snapshot -r "$cur"
###
### find newest snapshot matching the tag on dest
###
last="$(ZFS "$desthost" list -d 1 -t snapshot -H -S creation -o name $destfs/$srcbase 2>/dev/null \
| grep -F "@${tag}_" | head -n1 | cut -f2 -d@)"
###
### send & receive
###
# 1st time: send full snapshot
if [[ -z $last ]] ; then
log "sending full recursive snapshot from $src to $dest"
ZFS "$srchost" send -R "$cur" | ZFS "$desthost" receive -Fud "$destfs"
# special case: tagged snapshots exist on dest, but src has rotated through all
elif ! ZFS "$srchost" list $srcfs@$last &>/dev/null ; then
die 1 "no incremental path from from $src to $dest"
# normal case: send incremental
else
log "sending incremental snapshot from $src to $dest (${last#${tag}_}..${cur#*@${tag}_})"
ZFS "$srchost" send -R -I "$last" "$cur" | ZFS "$desthost" receive -Fud "$destfs"
fi
###
### clean up old snapshots
###
for snap in $(ZFS "$srchost" list -d 1 -t snapshot -H -S creation -o name $srcfs \
| grep -F "@${tag}_" | cut -f2 -d@ | tail -n+$((keep+1)) ) ;
do
ZFS "$srchost" destroy -r $srcfs@$snap
done