Configuration Languages

March 19, 2010

I spotted this blog post about using (or not) domain specific languages to customise programs. I can’t help feeling there is an interesting overlap here with the way we configure entire systems, we all face similar problems they are just at different levels. Just because a piece of software can be configured using the full power of Perl doesn’t make it a good thing (yes, I’m looking at you, RT…). LCFG deliberately has a minimal “language” for this very reason, it offers far fewer ways in which people can shoot themselves in the foot (as long as we ignore cpp).

F12 ntp

March 19, 2010

To keep kerberos happy you need your client machines to have their clocks fairly well synchronised with the KDCs. The easiest way to achieve this is to use ntp. I’ve added an LCFG header, inf/options/ntp.h which uses the file component to do a simple setup on F12. The file /etc/ntp.conf now just contains:

driftfile /var/lib/ntp/drift
restrict default kod nomodify notrap nopeer noquery
restrict -6 default kod nomodify notrap nopeer noquery
restrict -6 ::1
includefile /etc/ntp/crypto/pw
keys /etc/ntp/keys

As usual, one of the problems with the file component is that it cannot restart services after a configuration file has changed. So, once this is in place it is necessary to do /etc/init.d/ntpd restart.

If ntpd was not previously running (you can check first) then it is necessary to use chkconfig to activate the service:

# chkconfig --list ntpd
ntpd            0:off   1:off   2:off   3:off   4:off   5:off   6:off
# chkconfig --level 2345 ntpd on
chkconfig --list ntpd
ntpd            0:off   1:off   2:on    3:on    4:on    5:on    6:off