Nagios check_mailq pluggin failing

Problem:

I was trying to add mail Queue monitoring for sendmail mta with the default check_mailq plugin. check_mailq was queried using nrpe which was demonized under xinetd. Even after the basic configuration, nrpe started crying about some access related problem (nrpe checks were called by nagios user)

[root@blackbox libexec]# ./check_nrpe -H localhost -c mailq
CRITICAL: Error code 78 returned from /usr/bin/mailq
[root@blackbox libexec]#

Solution:

1. Checked nrpe.cfg and verified that the configuration is correct --> Positive

[root@blackbox libexec]# grep mailq /usr/local/nagios/etc/nrpe.cfg
command[mailq]=/usr/local/nagios/libexec/check_mailq -M sendmail -w 40 -c 50
[root@blackbox libexec]#

2. Added sudo privileges for nagios user to run /usr/bin/mailq without password

[root@blackbox libexec]# grep mailq /etc/sudoers
nagios BLACKBOX_HOSTS = (root) NOPASSWD: /usr/bin/mailq
[root@blackbox libexec]#

3. Added the missing /usr/bin/sudo command on check_mailq script from nagios pluggins package. PATH_TO_MAILQ is called from utils.pm module

[root@blackbox libexec]# grep sudo /usr/local/nagios/libexec/check_mailq
if (! open (MAILQ, "/usr/bin/sudo $utils::PATH_TO_MAILQ | " ) ) {
[root@blackbox libexec]#

Yayy!! Its working..

[root@blackbox libexec]# ./check_nrpe -H localhost -c mailq
OK: mailq is empty|unsent=0;40;50;0
[root@blackbox libexec]#