Following on from some experience with DNS misbehaviour on an old syslogd
instance,
I was forced to add the ability to force a re-read of resolv.conf upon SIGHUP.
This allowed me to
change the DNS server that a given central syslog server interrogated without
requiring
a complete restart of the daemon - which would otherwise have potentially lost
messages.
Without this tweak, a given process effectively "caches forever" the contents of
resolv.conf
during the first call to gethostbyaddr().
In particular, if I needed to take out a given DNS server for
maintenance/upgrade, I could swing
DNS service elsewhere and avoid disrupting the natural behaviour of the syslog
daemon.
As far as I can tell syslog-ng doesn't have this feature. As far as I can tell,
adding the feature
merely requires 2 extra lines of code in main.c as per below.
If it meets general approval, perhaps the feature could be added in the next
patch release.
Ted
Within:
/usr/src/syslog-ng/syslog-ng-1.5.20/src/main.c
add the following:
........
#include <resolv.h> <<<extra line
........
if (sighuprecvd) {
sighuprecvd = 0;
if (!backend->super.reloading) {
notice("SIGHUP received, restarting
syslog-ng\n");
res_init(); <<< extra line
if (!debug_flag) {
set_error_stream(2, 0);
set_internal_cfg(NULL);
}
backend->super.reloading = 1;
reload_config = 1;
r.backend = backend;
r.state = -1;
/* wait a second to flush buffers */
io_callout(&backend->super, 1, &r.super);
}
}
........
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