iankelling.org Git - distro-setup/blob - btrbk-run

   1 #!/bin/bash
   2 # Copyright (C) 2016 Ian Kelling
   3
   4 # Licensed under the Apache License, Version 2.0 (the "License");
   5 # you may not use this file except in compliance with the License.
   6 # You may obtain a copy of the License at
   7
   8 #     http://www.apache.org/licenses/LICENSE-2.0
   9
  10 # Unless required by applicable law or agreed to in writing, software
  11 # distributed under the License is distributed on an "AS IS" BASIS,
  12 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13 # See the License for the specific language governing permissions and
  14 # limitations under the License.
  15
  16
  17 # todo: if we cancel in the middle of a btrfs send, then run again
  18 # immediately, the received subvolume doesn't get a Received UUID:
  19 # field, and we won't mount it. Need to figure out a solution that will
  20 # fix this.
  21
  22
  23 [[ $EUID == 0 ]] || exec sudo -E "${BASH_SOURCE[0]}" "$@"
  24
  25 source /usr/local/lib/err
  26
  27 usage() {
  28   cat <<'EOF'
  29 btrbk-run [OPTIONS] [run|resume|archive]
  30 usually -t TARGET_HOST or -s SOURCE_HOST
  31
  32 Note, at source location, intentionally not executable, run and read
  33 install-my-scripts.
  34
  35 EOF
  36   echo "top of script file:"
  37   sed -n '1,/^[# ]*end command line/{p;b};q' "$0"
  38   exit $1
  39 }
  40
  41
  42
  43 script_name="${BASH_SOURCE[0]}"
  44 script_name="${script_name##*/}"
  45 pre="${SSH_CLIENT:+$HOSTNAME} $script_name:"
  46 m() { if $verbose; then printf "$pre%s\n"  "$*"; fi;  "$@"; }
  47 e() { printf "$pre%s\n"  "$*"; }
  48 die() { printf "$pre%s\n" "$*" >&2; echo "exiting with status 1" >&2; exit 1; }
  49 mexit() { echo "$pre: exiting with status $1"; exit $1; }
  50
  51 # latest $MAIL_HOST
  52 if [[ -e /b/bash_unpublished/source-state ]]; then
  53   source /b/bash_unpublished/source-state
  54 fi
  55
  56 # note q is owned by root:1000
  57
  58 mountpoints=()
  59
  60 rsync_mountpoint=/q
  61
  62 ret=0
  63 # default options
  64 conf_only=false
  65 dry_run=false # mostly for testing
  66 rate_limit=no
  67 verbose=true; verbose_arg=-v
  68 if [[ $INVOCATION_ID ]]; then
  69   # INVOCATION_ID means running as a systemd service. we cant show progress in this case,
  70   # but if we pass the arg, it will insert mbuffer into the command.
  71   progress_arg=
  72 else
  73   progress_arg="--progress"
  74 fi
  75 incremental_strict=false
  76 pull_reexec=false
  77
  78 default_args_file=/etc/btrbk-run.conf
  79 if [[ -s $default_args_file ]]; then
  80   # shellcheck disable=SC2046 # we want word splitting
  81   set -- $(< $default_args_file) "$@"
  82   # i havent used this feature yet, so warn about it
  83   echo "$0: warning: default btrbk-run options set in $default_args_file (sleeping 5 seconds):"
  84   cat $default_args_file
  85   sleep 5
  86 fi
  87
  88 targets=()
  89 early=false
  90 cron=false
  91 fast=false
  92 kd_spread_maybe=false
  93 orig_args=("$@")
  94 temp=$(getopt -l cron,fast,pull-reexec,help 23ceikl:m:npqrs:t:vh "$@") || usage 1
  95 eval set -- "$temp"
  96 while true; do
  97   case $1 in
  98     # some behaviors specific to running under cron:
  99     # - skip hosts where xprintidle haven't been idle recently
 100     # - if we can't ssh to 1 or more hosts, still do the rest
 101     # - if we aren't MAIL_HOST and no -m or -s, just exit
 102     --cron)
 103       cron=true
 104       pre=
 105       ;;
 106     # for the rare case we want to run multiple instances at the same time
 107     -2) conf_suf=2 ;;
 108     -3) conf_suf=3 ;;
 109     # only creates the config file, does not run btrbk
 110     -c) conf_only=true ;;
 111     # quit early, just btrbk, no extra remounting etc.
 112     -e) early=true ;;
 113     # skip various checks. when we run twice in a row for
 114     # switch mail-host, no need to repeat the same checks again.
 115     --fast) fast=true ;;
 116     -i) incremental_strict=true ;;
 117     # note this implies resume
 118     -k) kd_spread_maybe=true ;;
 119     # bytes per second, suffix k m g
 120     -l) rate_limit=$2; shift ;;
 121     # Comma separated mountpoints to backup. This has defaults set below.
 122     -m) IFS=, mountpoints=($2); unset IFS; shift ;;
 123     -n) dry_run=true ;;
 124     # hide progress
 125     -p) progress_arg= ;;
 126     # internal option for rerunning under newer SOURCE_HOST version.
 127     --pull-reexec) pull_reexec=true;;
 128     # quiet
 129     -q) verbose=false; verbose_arg=; progress_arg= ;;
 130     # source host to receive a backup from
 131     -s)
 132       source=$2
 133       bbksource=$source
 134       if [[ $source == *:* ]]; then
 135         bbksource="[$source]"
 136       fi
 137       shift
 138       ;;
 139     # target hosts to send to. empty is valid for just doing local
 140     # snapshot. we have default hosts we will populate.
 141     -t) IFS=, targets=($2); unset IFS; shift ;;
 142     # verbose.
 143     -v) verbose=true; verbose_arg=-v ;;
 144     -h|--help) usage ;;
 145     --) shift; break ;;
 146     *) die "Internal error!" ;;
 147   esac
 148   shift
 149 done
 150
 151 if $kd_spread_maybe; then
 152   if [[ $1 && $1 != resume ]]; then
 153     die "dont pass -k without resume or empty run arg"
 154   fi
 155   cmd_arg=resume
 156 fi
 157
 158
 159 cmd_arg=${1:-run}
 160
 161
 162 std_preserve="36h 14d 8w 24m"
 163 q_preserve="18h 14d 8w"
 164
 165 case $cmd_arg in
 166   run|resume) : ;;
 167
 168   # This works better than the normal archive command. We have to
 169   # specify the mount points, but that is what we are used to doing and
 170   # we prefer it. Another difference is that archive works recursively
 171   # and we don't care about that. Sometimes we may still want to run
 172   # btrbk archive, but it doesn't even use the config file, so just
 173   # run it directly, eg:
 174   # time s btrbk -v archive /mnt/r7/amy/boot/btrbk ssh://bo/mnt/boot2/btrbk
 175   archive)
 176     cmd_arg=resume
 177     std_preserve="999h 999d 999w 999m"
 178     q_preserve="$std_preserve"
 179     preserve_arg=-p
 180     ;;
 181   *) die "untested command arg" ;;
 182 esac
 183
 184 if (( $# > 1 )); then
 185   die: "only 1 nonoption arg is supported"
 186 fi
 187
 188 if [[ -v targets && $source ]]; then
 189   # note, this doesnt need to be the case, but
 190   # we would need to think about it.
 191   die "error: -t and -s are mutually exclusive"
 192 fi
 193
 194 ### end options parsing
 195
 196 # remove path from earlier version of btrbk
 197 rm -f /usr/sbin/btrbk
 198 # note, this still works as intended if there is no /usr/bin/btrbk
 199 if [[ /a/opt/btrbk/btrbk -nt /usr/bin/btrbk ]]; then
 200   if [[ -e /b/distro-functions/src/package-manager-abstractions ]]; then
 201     . /b/distro-functions/src/package-manager-abstractions
 202     pi asciidoctor
 203   fi
 204   cd /a/opt/btrbk
 205   m make install
 206 fi
 207
 208 # TODO: i wonder if there should be an option to send to the default
 209 # targets, plus any given on the command line.
 210
 211
 212
 213 kd_spread=false
 214 # set default targets
 215 if [[ ! -v targets && ! $source ]]; then
 216   if $cron; then
 217     if [[ $HOSTNAME != "$MAIL_HOST" ]]; then
 218       if $kd_spread_maybe && [[ $HOSTNAME == kd && $MAIL_HOST == x3 ]]; then
 219         if ping -q -c1 -w1 x3.office.fsf.org &>/dev/null; then
 220           work_host=x3.office.fsf.org
 221         elif ping -q -c1 -w1 x3wg.b8.nz &>/dev/null; then
 222           work_host=x3wg.b8.nz
 223         fi
 224         if [[ $work_host ]]; then
 225           source_state="$(ssh $work_host cat /a/bin/bash_unpublished/source-state)"
 226           eval "$source_state"
 227           if [[ $MAIL_HOST == x3 ]]; then
 228             kd_spread=true
 229           else
 230             echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 231             mexit 0
 232           fi
 233         else
 234           echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 235           mexit 0
 236         fi
 237       else
 238         echo "MAIL_HOST=$MAIL_HOST, nothing to do"
 239         mexit 0
 240       fi
 241     fi
 242   fi
 243
 244   at_work=false
 245   at_home=false
 246
 247   case $HOSTNAME in
 248     kw|kd|frodo|x2|x3|sy) : ;;
 249     *)
 250       die "error: no default targets for this host, use -t"
 251       ;;
 252   esac
 253
 254   case $HOSTNAME in
 255     kw)
 256       at_work=true
 257       ;;&
 258     kd|frodo)
 259       at_home=true
 260       ;;&
 261     x2|x3|sy)
 262       if [[ $(dig +short @10.2.0.1 -x 10.2.0.2 2>&1 ||:) == kd.b8.nz. ]] \
 263            && ip n show 10.2.0.1 | grep . &>/dev/null; then
 264         at_home=true
 265       elif ping -q -c1 -w1 hal.office.fsf.org &>/dev/null \
 266           && ip n show 192.168.0.26 | grep . &>/dev/null; then
 267         at_work=true
 268       fi
 269       ;;&
 270     *)
 271       if $at_home; then
 272         if ! $kd_spread && [[ $HOSTNAME != x3 ]]; then
 273           # main work machine
 274           if ping -q -c1 -w1 x3.office.fsf.org &>/dev/null; then
 275             targets+=(x3.office.fsf.org)
 276           elif ping -q -c1 -w1 $h.b8.nz &>/dev/null; then
 277             # in case we took it home
 278             targets+=(x3.b8.nz)
 279           else
 280             targets+=(x3wg.b8.nz)
 281           fi
 282         fi
 283         # temporarily disabled while doing recovery
 284         #        for h in frodo kd; do
 285         for h in kd; do
 286           if [[ $HOSTNAME == "$h" ]]; then
 287             continue
 288           fi
 289           targets+=($h.b8.nz)
 290         done
 291         for h in x2 sy; do
 292           if [[ $HOSTNAME == "$h" ]]; then
 293             continue
 294           fi
 295           if ping -q -c1 -w1 $h.b8.nz &>/dev/null; then
 296             targets+=($h.b8.nz)
 297           elif ping -q -c1 -w1 ${h}w.b8.nz &>/dev/null; then
 298             targets+=(${h}w.b8.nz)
 299           fi
 300         done
 301       elif $at_work; then
 302         targets+=(i.b8.nz)
 303         for h in x2 x3 kw; do
 304           if [[ $HOSTNAME == "$h" ]]; then
 305             continue
 306           fi
 307           if ping -q -c1 -w1 $h.office.fsf.org &>/dev/null; then
 308             targets+=($h.office.fsf.org)
 309           fi
 310         done
 311       else
 312         targets+=(i.b8.nz)
 313       fi
 314       ;;
 315   esac
 316 fi
 317
 318 if $verbose; then
 319   printf "$pre options: conf_only=%s\ndry_run=%s\nrate_limit=%s\nverbose=%s\ncmd_arg=%s" "$conf_only" "$dry_run" "$rate_limit" "$verbose" "$cmd_arg"
 320 fi
 321
 322
 323 if [[ -v targets ]]; then
 324   echo "targets: ${targets[*]}"
 325 fi
 326
 327 if [[ $source ]]; then
 328   echo "source: $source"
 329 fi
 330
 331 if [[ ${mountpoints[0]} ]]; then
 332   for mp in ${mountpoints[@]}; do
 333     if [[ -e /nocow/btrfs-stale/$mp ]]; then
 334       die "error: $mp is stale, mount-latest-subvol first"
 335     fi
 336   done
 337 else
 338   # set default mountpoints
 339   if [[ ${targets[0]} == tp ]]; then
 340     prospective_mps=(/a)
 341   else
 342     case $HOSTNAME in
 343       *)
 344         prospective_mps=()
 345         if [[ $source ]]; then
 346           source_state="$(ssh $source cat /a/bin/bash_unpublished/source-state)"
 347           eval "$source_state"
 348           source_host="$(ssh $source cat /etc/hostname)"
 349           if [[ $source_host == "$MAIL_HOST" ]]; then
 350             prospective_mps+=(/o)
 351           fi
 352           if [[ $source_host == "$HOST2" ]]; then
 353             prospective_mps+=(/a /ar /qr /q)
 354           fi
 355         else
 356           if [[ $HOSTNAME == "$MAIL_HOST" ]]; then
 357             prospective_mps+=(/o)
 358           fi
 359           if [[ $HOSTNAME == "$HOST2" ]]; then
 360             prospective_mps+=(/a /ar /qr /q)
 361           fi
 362           if $kd_spread; then
 363             prospective_mps=(/a /ar /o /qr /q)
 364           fi
 365         fi
 366         # note: put q last just in case its specific retention options were to
 367         # affect other config sections. I havent tested if that is the case.
 368         ;;
 369     esac
 370   fi
 371   for mp in ${prospective_mps[@]}; do # default mountpoints to sync
 372     if [[ -e /nocow/btrfs-stale/$mp ]]; then
 373       e "warning: $mp stale, not adding to default mountpoints"
 374       continue
 375     fi
 376     if awk '{print $2}' /etc/fstab | grep -xF $mp &>/dev/null; then
 377       mountpoints+=($mp)
 378     fi
 379   done
 380 fi
 381
 382 if (( ! ${#mountpoints[@]} )); then
 383   die didnt get mountpoint arg and had no defaults
 384 fi
 385
 386 echo "mountpoints: ${mountpoints[*]}"
 387
 388 ##### end command line parsing ########
 389
 390 # todo: this has a timing problem, since btrbk.timer could activate the service after this check.
 391 if ! $fast && [[ $source ]]; then
 392   if [[ $(ssh $source ps --no-headers -o comm 1) == systemd ]]; then
 393     status=$(ssh $source systemctl is-active btrbk.service) || : # normally returns 3
 394     case $status in
 395       inactive|failed) : ;;
 396       *)
 397         echo "$0: error: cron btrbk is running on source. exiting out of caution"
 398         mexit 1
 399     esac
 400   fi
 401 fi
 402
 403 # pull_reexec stops us from getting into an infinite loop if there is some
 404 # kind of weird problem
 405 pulla=false
 406 for m in "${mountpoints[@]}"; do
 407   if [[ $m == /a ]]; then
 408     pulla=true
 409     break
 410   fi
 411 done
 412 if ! $pull_reexec && [[ $source ]] && $pulla ; then
 413   tmpf=$(mktemp)
 414   m rsync -ra $source:/usr/local/bin/{mount-latest-subvol,check-subvol-stale} /usr/local/bin
 415   m rsync -ra $source:/usr/local/lib/err /usr/local/lib
 416   m scp $source:/a/bin/distro-setup/btrbk-run $tmpf
 417   if ! diff -q $tmpf ${BASH_SOURCE[0]}; then
 418     e "found different version on host $source. reexecing"
 419     install -T $tmpf /usr/local/bin/btrbk-run
 420     m /usr/local/bin/btrbk-run --pull-reexec "${orig_args[@]}"
 421     mexit 0
 422   fi
 423 fi
 424
 425
 426 if ! command -v btrbk &>/dev/null; then
 427   die "error: no btrbk binary found"
 428 fi
 429
 430 if ! $fast; then
 431   # if our mountpoints are from stale snapshots,
 432   # it doesn't make sense to do a backup.
 433   m check-subvol-stale ${mountpoints[@]} || die "found stale mountpoints in ${mountpoints[*]}"
 434
 435   # for an initial run, btrbk requires the dir to exist.
 436   mkdir -p /mnt/{root,o}/btrbk
 437 fi
 438 local_zone=$(date +%z)
 439
 440 if [[ $source ]]; then
 441   if $fast; then
 442     zone=$local_zone
 443   else
 444     if ! zone=$(ssh root@$source date +%z); then
 445       if $conf_only; then
 446         echo "$0: warning: failed to ssh to root@$source"
 447       else
 448         die failed to ssh to root@$source
 449       fi
 450     fi
 451     if [[ $zone != "$local_zone" ]]; then
 452       die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
 453     fi
 454   fi
 455 else
 456
 457   sshable=()
 458   sshfail=()
 459   for h in ${targets[@]}; do
 460     if $fast || $conf_only; then
 461       # Use some typical values in this case
 462       root_size=$(( 1024 * 1024 * 2000 )) #2tb
 463       percent_used=10
 464       zone=$(date +%z)
 465     elif remote_str=$(timeout -s 9 6 ssh root@$h "mkdir -p /mnt/root/btrbk /mnt/o/btrbk && date +%z && df --output=size,pcent / | tail -n1"); then
 466       mapfile -t tmp_array <<<"$remote_str"
 467       zone="${tmp_array[0]}"
 468       IFS=" " read -r root_size percent_used <<<"${tmp_array[1]}"
 469       percent_used=${percent_used%%%}
 470
 471       if (( ${#tmp_array[@]} != 2 )); then
 472         die "error: didnt get 2 lines in test ssh to target $h. investigate"
 473       fi
 474       case $percent_used in
 475         [0-9]|[1-9][0-9]) : ;;
 476         *)
 477           die "error: didnt get percent disk use in test ssh to target $h. investigate"
 478           ;;
 479       esac
 480     else
 481       sshfail+=($h)
 482       continue
 483     fi
 484
 485     # we may be booted into a bootstrap fs or something
 486     min_root_kb=$(( 1024 * 1024 * 200 )) # 200 gb
 487     if (( root_size < min_root_kb )); then
 488       continue
 489     fi
 490
 491     if (( percent_used >= 98 )); then
 492       die "error: filesystem on target $h is $percent_used % full"
 493     fi
 494
 495     # on sy, xprintidle is resetting every 12 seconds even when not
 496     # idle, i dunno why, instead we are checking if the screen is locked,
 497     # which is good enough.
 498     #
 499     # This is a separate ssh because the command can fail and thatis ok.
 500     if $cron; then
 501       locked=false
 502       if lock_info=$(timeout -s 9 6 ssh $h DISPLAY=:0 xscreensaver-command -time); then
 503         if [[ $lock_info != *non-blanked* ]]; then
 504           locked=true
 505         fi
 506       else
 507         locked=true
 508       fi
 509       if ! $locked; then
 510         # Ignore this host. i sometimes use a non-main machine for
 511         # testing or web browsing, knowing that everything will be wiped
 512         # by the next backup, but I dont want it to happen as Im using
 513         # it from cronjob.
 514         e "warning: $h: seems to be actively in use, skipping for now"
 515         continue
 516       fi
 517     fi
 518     sshable+=($h)
 519     if [[ $zone != "$local_zone" ]]; then
 520       die "error: dont confuse yourself with multiple time zones. $h has different timezone than localhost"
 521     fi
 522   done
 523   if [[ ! ${sshable[*]} ]] || { ! $cron && [[ ${sshfail[*]} ]]; }; then
 524     die "failed to ssh to hosts: ${sshfail[*]}"
 525   else
 526     if [[ ${sshfail[*]} ]]; then
 527       ret=1
 528       e "error: failed to ssh to ${sshfail[*]} but continuing with other hosts"
 529     fi
 530     targets=(${sshable[@]})
 531   fi
 532 fi
 533
 534
 535 cat >/etc/btrbk$conf_suf.conf <<EOF
 536 ssh_identity /q/root/h
 537 #ssh_identity /root/.ssh/home
 538
 539 # Just a guess that local7 is a good facility to pick.
 540 # It's a bit odd that the transaction log has to be logged to
 541 # a file or syslog, while other output is sent to std out.
 542 # The man does not mention a way for them to be together, but
 543 # I dunno if setting a log level like warn might also output
 544 # transaction info.
 545 transaction_syslog local7
 546
 547 # trying this out
 548 #stream_compress zstd
 549
 550 # so we only run one at a time
 551 lockfile                   /var/lock/btrbk$conf_suf.lock
 552
 553 # default format of short does not accomidate hourly preservation setting
 554 timestamp_format long-iso
 555
 556 # only make a snapshot if things have changed
 557 snapshot_create onchange
 558 # I could make this different from target_preserve,
 559 # if one disk had less space.
 560 # for now, keeping them equal.
 561 snapshot_preserve $std_preserve
 562 snapshot_preserve_min 6h
 563 snapshot_dir btrbk
 564 # so, total backups = ~58
 565 target_preserve $std_preserve
 566 target_preserve_min 6h
 567
 568 # i tried this when investigating: clone no source subvolume found error
 569 #incremental_prefs sro:1 srn:1 sao san:1 aro:1 arn:1
 570
 571 # if something fails and it's not obvious, try doing
 572 # btrbk -l debug -v dryrun
 573
 574 rate_limit $rate_limit
 575 EOF
 576
 577 if $incremental_strict; then
 578   cat >>/etc/btrbk$conf_suf.conf <<EOF
 579 incremental strict
 580 EOF
 581 fi
 582
 583 qconf() {
 584   case $sub in
 585     q)
 586       # q has sensitive data i dont want to backup for so long
 587       cat >>/etc/btrbk$conf_suf.conf <<EOF
 588 snapshot_preserve $q_preserve
 589 snapshot_preserve_min 2h
 590 snapshot_dir btrbk
 591 target_preserve $q_preserve
 592 target_preserve_min 2h
 593 EOF
 594       ;;
 595   esac
 596
 597 }
 598
 599 # make /q be last
 600 mp_count=${#mountpoints[@]}
 601 for (( i=0; i < mp_count - 1 ; i++ )); do
 602   if [[ ${mountpoints[i]} == /q ]]; then
 603     unset "mountpoints[i]"
 604     mountpoints+=(/q)
 605   fi
 606 done
 607
 608 for m in ${mountpoints[@]}; do
 609   case $m in
 610     /o)
 611       vol=/mnt/o
 612       ;;
 613     *)
 614       vol=/mnt/root
 615       ;;
 616   esac
 617
 618   sub=${m#/}
 619   if [[ $source ]]; then
 620     cat >>/etc/btrbk$conf_suf.conf <<EOF
 621 volume ssh://$bbksource$vol
 622 subvolume $sub
 623 EOF
 624     qconf
 625     cat >>/etc/btrbk$conf_suf.conf <<EOF
 626 target send-receive $vol/btrbk
 627 EOF
 628   fi
 629   if (( ${#targets[@]} )); then
 630     cat >>/etc/btrbk$conf_suf.conf <<EOF
 631 volume $vol
 632 subvolume $sub
 633 EOF
 634     qconf
 635     for tg in ${targets[@]}; do
 636       # handle ipv6
 637       if [[ $tg == *:* ]]; then
 638         tg="[$tg]"
 639       fi
 640       cat >>/etc/btrbk$conf_suf.conf <<EOF
 641 target send-receive ssh://$tg$vol/btrbk
 642 EOF
 643     done
 644   fi
 645 done
 646
 647 # todo: umount first to ensure we don't have any errors
 648 # todo: do some kill fuser stuff to make umount more reliable
 649
 650
 651 if $conf_only; then
 652   mexit 0
 653 fi
 654
 655
 656
 657 if $dry_run; then
 658   m btrbk -c /etc/btrbk$conf_suf.conf -v -n $cmd_arg
 659   mexit 0
 660 fi
 661 # -q and just using the syslog option seemed nice,
 662 # but it doesn't show when a send has a parent and when it doesn't.
 663 m btrbk -c /etc/btrbk$conf_suf.conf $preserve_arg $verbose_arg $progress_arg $cmd_arg
 664
 665 if $early; then
 666   exit 0
 667 fi
 668
 669 # todo: tp not valid anymore.
 670 # if we have it, sync to systems which don't
 671 if mountpoint $rsync_mountpoint >/dev/null; then
 672   for tg in ${targets[@]}; do
 673     case $tg in
 674       tp)
 675         dirs=(/p/c/machine_specific/tp)
 676         for x in /p/c/machine_specific/*.hosts; do
 677           if grep -qxF $tg $x; then
 678             dirs+=(${x%.hosts})
 679           fi
 680         done
 681         m rsync -aSAXPH --specials --devices --delete --relative ${dirs[@]} root@$tg:/
 682         ;;
 683     esac
 684   done
 685 fi
 686
 687 subvols=()
 688 for mp in "${mountpoints[@]}"; do
 689   subvols+=("${mp##*/}")
 690 done
 691 if [[ $source ]]; then
 692   m mount-latest-subvol "${subvols[@]}"
 693 else
 694   for tg in ${targets[@]}; do
 695     m /a/exe/mount-latest-remote "$tg" "${subvols[@]}" || ret=$?
 696   done
 697 fi
 698
 699 if [[ $ret == 0 ]]; then
 700   for tg in ${targets[@]}; do
 701     :
 702     ssh root@$tg /a/exe/mail-backup-clean
 703   done
 704 fi
 705
 706 mexit $ret
 707
 708 # todo: move variable data we don't care about backing up
 709 # to /nocow and symlink it.
 710
 711
 712 # background on btrbk timezones. with short/long, timestamps use local time.
 713 # for long, if your local time moves backwards, by moving timezones or
 714 # for an hour when daylight savings changes it, you will temporarily get
 715 # a more aggressive retention policy for the overlapping period, and
 716 # vice versa for the opposite timezone move. The alternative is using
 717 # long-iso, which puts timezone info into the timestamp, which means
 718 # that instead of shifting time, you shift the start of day/week/month
 719 # which is used for retention to your new local time, which means for
 720 # example, if you moved forward by 8 hours, the daily/weekly/monthly
 721 # retention will be 8 hours more aggressive since midnight is at a new
 722 # time, unless you fake the timzeone using the TZ env variable.
 723 # However, in the short term, there will be no inconsistencies.
 724 # I don't see any problem with shifting when the day starts for
 725 # retention, so I'm using long-iso.
 726
 727 # note to create a long-iso timestamp: date +%Y%m%dT%H%M%S%z