> On Aug 30, 2022, at 1:12 PM, Casey Deccio <ca...@deccio.net> wrote:
>
> I am having trouble tracking down a bug in my monitoring setup. It all
> happened when I upgraded the monitored host (host B in my example below) to
> bullseye. Note that Host A is also running bullseye, but the problem didn't
> show itself until Host B was upgraded.
With some help over at the bind-users mailing list [1], I discovered that
nrpe-ng closes stdin when launching the command [2], and the new version of
nslookup (invoked by check_dns) has issues when stdin is closed [3].
Redirecting stdin to /dev/null fixes the issue:
$ diff -u /usr/lib/python3/dist-packages/nrpe_ng/commands.py{.old,}
--- /usr/lib/python3/dist-packages/nrpe_ng/commands.py.old 2017-08-08
13:05:02.000000000 -0600
+++ /usr/lib/python3/dist-packages/nrpe_ng/commands.py 2022-09-13
17:00:36.767239885 -0600
@@ -85,6 +85,7 @@
proc = tornado.process.Subprocess(
run_args,
+ stdin=subprocess.DEVNULL,
stdout=tornado.process.Subprocess.STREAM,
close_fds=True,
env=env)
I've filed a bug report [4].
Thanks,
Casey
[1] https://lists.isc.org/pipermail/bind-users/2022-September/106666.html
[2] https://github.com/bootc/nrpe-ng/blob/master/nrpe_ng/commands.py#L86
[3] https://github.com/libuv/libuv/blob/v1.x/src/unix/core.c#L602
[4] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1019718
