graygnuorg
commented
3 weeks ago That could be done, of course, but it would take some time to be implemented. I'll let you know when I have something tangible to test. In the meantime, you can try the following watchdog. It restarts pound when the host name given as argument changes its IP. The script uses at to schedule its next startup time and rounds it up to the nearest minute, which should be enough for most real-time ttls. However, it should be easy to modify it to run with the second precision as well. It uses systemctl to restart pound, edit it if you use some other command:
#!/bin/sh
host=${1:?}
prev=$2
set -- $(dig +noall +answer $host|awk '$4 == "A" || $4 == "AAAA" {print $2 " " $5}'|head -1)
if [ $# -ne 2 ]; then
echo >&2 "$0: failed to resolve $host"
exit 1
fi
if [ "$prev" != $2 ]; then
echo >&2 "$0: $host changed IP from $prev to $2"
prev=$2
systemctl restart pound
fi
n=$(( ( $1 + 59 ) / 60 ))
echo "$0 $host $prev" | at now + $n minute 2>&1 | \
sed -e '/^warning: commands will be executed using/d' \
-e '/^job [0-9][0-9]* at/d'
beelze
One of my configurations includes backend server that may sometimes change its ip address. It is relatively rare (a couple times a week) but I need to restart pound every time it happens.
I understand that resolving symbolic server name every time is expensive and even not needed (in most cases), but sometimes it may be convenient (low load, "cheap" local resolve). Is there any possibility to mark backend address "dynamic"? Or maybe add appropriate config directive?