Hi,
Maxim Khitrov wrote on Fri, Jan 30, 2015 at 10:22:23AM -0500:
> I wrote two simple functions for rc.shutdown and rc.login that
> save/restore unbound cache when the system is restarted. Since each
> record has a relative TTL field, the cache can only be restored within
> a short time window to avoid serving stale data to clients. I set this
> window to 10 minutes; enough to survive a reboot, but not for any
> extended downtime. Is there any interest in including this
> functionality in the base OS (moved to /etc/rc)?
The purpose of rebooting is to reset the system to a clean state,
so clearing caches looks like a feature rather than a bug. Given
that even "unbound-control reload" flushes the cache, a reboot
should certainly do that, too. So i wouldn't even recommend showing
this to people as something they might add to their local scripts
if they want to. It just seems wrong.
Also note that the unbound-control(8) manual explicitly marks
load_cache as a debugging feature and warns that it may cause wrong
data to be served. On top of that, the version of unbound(8) running
after the reboot might be newer than the version running before,
so compatibility is questionable as well, so your proposal is very
fragile at best.
Besides, even if the goal would be desirable, which it is not, my
feeling is that this code is too specialized for adding to the boot
scripts.
Yours,
Ingo
> --- /var/backups/etc_rc.shutdown.current Mon Aug 4 21:03:16 2014
> +++ /etc/rc.shutdown Fri Jan 30 10:06:11 2015
> @@ -8,3 +8,17 @@
> powerdown=NO # set to YES for powerdown
>
> # Add your local shutdown actions here.
> +
> +save_unbound_cache() {
> + local db=/var/db/unbound.cache
> + /etc/rc.d/unbound check || return
> + echo -n 'saving unbound cache: '
> + if unbound-control dump_cache > $db; then
> + chmod 0600 $db
> + echo 'done.'
> + else
> + rm -f $db
> + fi
> +}
> +
> +save_unbound_cache
>
> --- /var/backups/etc_rc.local.current Mon Aug 4 21:03:16 2014
> +++ /etc/rc.local Fri Jan 30 10:07:00 2015
> @@ -4,3 +4,17 @@
> # can be done AFTER your system goes into securemode. For actions
> # which should be done BEFORE your system has gone into securemode
> # please see /etc/rc.securelevel.
> +
> +restore_unbound_cache() {
> + local db=/var/db/unbound.cache
> + test -s $db && /etc/rc.d/unbound check || return
> + echo -n 'restoring unbound cache: '
> + if [ $(($(date '+%s') - $(stat -qf '%m' $db))) -lt 600 ]; then
> + unbound-control load_cache < $db
> + else
> + echo 'failed (cache expired).'
> + fi
> + rm -f $db
> +}
> +
> +restore_unbound_cache
