Nagios showing error 500 sometimes

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zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Nagios showing error 500 sometimes

Post by zulu42 »

Hi all,
I'm new here and registered because I'm running out of ideas for the following problem:
I'm running a Nagios 3.5.1, installed via yum from an EPEL-repo on a RedHat 7.1-system.
I moved the log-files and configuration to a different location (separate disk). I enabled LDAP-Auth for the GUI in the /etc/httpd/conf.d/nagios.conf.
Everything is working pretty well except of one thing:
From time to time (~ every 30 refreshes) or when I click somewhere on the dashboard, I'm getting the "Error 500" and I can still see the menu on the right side, but no hosts or status-infos.
In the httpd-error-log I can see this at the same time e.g.:
[Thu Jan 14 12:00:16.239471 2016] [cgi:error] [pid 5026] [client 192.168.2.100:61945] End of script output before headers: status.cgi, referer: http://nagios001/nagios/cgi-bin//status ... ustypes=15
or:
[Thu Jan 14 11:09:06.246553 2016] [cgi:error] [pid 27117] [client 192.168.2.100:61203] End of script output before headers: status.cgi, referer: http://nagios001/nagios/side.php

From different posts, I could see, that it might has something to do with the file-permissions or incorrect configuration, but I check eversything I could find.

The strange thing is, that this error occurs only sometimes and not permanently. So my question is:
Could it be possible, that this is due to a high load of the nagios during executing checks or any file-locks or does anyone have another idea?

Thank you all in advance :)

BR
rkennedy
Posts: 6579
Joined: Mon Oct 05, 2015 11:45 am

Re: Nagios showing error 500 sometimes

Post by rkennedy »

I moved the log-files and configuration to a different location (separate disk)
What files did you move to a different location?

Was this happening before, or after you integrated LDAP? Can you post your apache configuration files?
Former Nagios Employee
zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Re: Nagios showing error 500 sometimes

Post by zulu42 »

I moved all configuration-files for:
Services-definition, Servicegroups-definition, Hosts-definition, Hostgroups-definition, Command-definition, Contact-definition, Checktime-definition
And I moved the nagios.log and the status.dat files.

Which config-files exactly?

This happend also before the LDAP-integration.
tmcdonald
Posts: 9117
Joined: Mon Sep 23, 2013 8:40 am

Re: Nagios showing error 500 sometimes

Post by tmcdonald »

What are the permissions on the status.cgi file?

Do you have selinux enabled? getenforce

How about suExec? We have seen that cause issues in the past: https://support.nagios.com/forum/viewto ... 20#p142073

https://httpd.apache.org/docs/2.2/suexec.html#enable
Former Nagios employee
zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Re: Nagios showing error 500 sometimes

Post by zulu42 »

Permissions on status.cgi:
ls -lah /usr/lib64/nagios/cgi-bin/status.cgi
-rwxr-xr-x. 1 root root 300K Feb 7 2014 /usr/lib64/nagios/cgi-bin/status.cgi

selinux is disabled.

The phpinfo() is giving me the following result:
Server API: Apache 2.0 Handler
So the server should not run in suexec-mode right?
rkennedy
Posts: 6579
Joined: Mon Oct 05, 2015 11:45 am

Re: Nagios showing error 500 sometimes

Post by rkennedy »

I believe the permissions need to be nagios:nagios, can you also post the output of the rest of the folder?

Code: Select all

ls -lah /usr/lib64/nagios/cgi-bin/
Former Nagios Employee
zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Re: Nagios showing error 500 sometimes

Post by zulu42 »

nagios001:/usr/lib64/nagios/cgi-bin# ls -lah
total 4.0M
drwxrwxr-x. 2 root root 4.0K Jan 14 09:39 .
drwxr-xr-x. 4 root root 34 Nov 5 11:34 ..
-rwxrwxr-x. 1 root root 288K Feb 7 2014 avail.cgi
-rwxrwxr-x. 1 root root 286K Feb 7 2014 cmd.cgi
-rwxrwxr-x. 1 root root 256K Feb 7 2014 config.cgi
-rwxrwxr-x. 1 root root 300K Feb 7 2014 extinfo.cgi
-rwxrwxr-x. 1 root root 251K Feb 7 2014 histogram.cgi
-rwxrwxr-x. 1 root root 227K Feb 7 2014 history.cgi
-rwxrwxr-x. 1 root root 227K Feb 7 2014 notifications.cgi
-rwxrwxr-x. 1 root root 219K Feb 7 2014 outages.cgi
-rwxrwxr-x. 1 root root 223K Feb 7 2014 showlog.cgi
-rwxr-xr-x. 1 nagios nagios 300K Feb 7 2014 status.cgi
-rwxrwxr-x. 1 root root 248K Feb 7 2014 statusmap.cgi
-rwxrwxr-x. 1 root root 240K Feb 7 2014 statuswml.cgi
-rwxrwxr-x. 1 root root 228K Feb 7 2014 statuswrl.cgi
-rwxrwxr-x. 1 root root 248K Feb 7 2014 summary.cgi
-rwxrwxr-x. 1 root root 240K Feb 7 2014 tac.cgi
-rwxrwxr-x. 1 root root 256K Feb 7 2014 trends.cgi

Changing the permissions didn't solve the problem.
As the problem is not occuring on every GUI-update, I really don't think it's a problem with the permissions or wrong config. Could it be due to high load?
rkennedy
Posts: 6579
Joined: Mon Oct 05, 2015 11:45 am

Re: Nagios showing error 500 sometimes

Post by rkennedy »

Yes, this could be the culprit, especially as this is happening at random.

What is the result of top|head -5? Also, how many CPUs do you have allocated to the machine?
Former Nagios Employee
zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Re: Nagios showing error 500 sometimes

Post by zulu42 »

top|head -5
top - 07:21:43 up 35 days, 21:02, 4 users, load average: 8.12, 5.53, 4.29
Tasks: 173 total, 2 running, 168 sleeping, 3 stopped, 0 zombie
%Cpu(s): 5.7 us, 1.5 sy, 0.0 ni, 92.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 8011552 total, 1974816 free, 775024 used, 5261712 buff/cache
KiB Swap: 1257468 total, 1256288 free, 1180 used. 6589452 avail Mem

The VM has 4 CPU-Cores. Should I consider upgrading the CPUs or the RAM or both? There is also an alert for the localhost-load on this server.
zulu42
Posts: 17
Joined: Thu Jan 14, 2016 7:11 am

Re: Nagios showing error 500 sometimes

Post by zulu42 »

Short update:
I've upgraded the RAM to 12GB. Still have Four CPU-cores:

top - 13:50:47 up 1:11, 2 users, load average: 0.02, 0.06, 0.11
Tasks: 184 total, 3 running, 181 sleeping, 0 stopped, 0 zombie
%Cpu(s): 6.1 us, 1.3 sy, 0.0 ni, 92.5 id, 0.1 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 12140304 total, 11242764 free, 434120 used, 463420 buff/cache
KiB Swap: 1257468 total, 1257468 free, 0 used. 11446752 avail Mem
Locked