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30. January 2013

Nagios / Icinga: Monitor (local) memory usage

Filed under: Linux,Server Administration — Tags: , , , , , , , , , , , , , — Christopher Kramer @ 17:55

Nagios and its fork icinga are great monitoring tools. They come with a bundle of plugins to monitor standard services such as HTTP, SMTP, POP3, load and stuff like that. And there are lots of 3rd party plugins available for almost everything else you can think of.

But one standard thing that is missing in the official nagios-plugins package is a plugin to check memory usage (of the local machine).

So here is how to install one. I assume a Debian system with Icinga running – you might want to adjust paths for other distros or nagios.

  1. Download the plugin here
    e.g. from the shell:

    wget https://exchange.icinga.com/exchange/check_memory/files/784/check_memory.pl
  2. Then move the file to the other plugins
    mv check_memory.pl /usr/lib/nagios/plugins/check_memory.pl
  3. Make it executable
    chmod +x /usr/lib/nagios/plugins/check_memory.pl
  4. Try to run it:
    perl /usr/lib/nagios/plugins/check_memory.pl -w 50% -c 25%
  5. This should give something like “CHECK_MEMORY OK – […] free […]”. If an error occurs, you probably need to install the perl module Nagios::Plugin. On Debian, the easiest way is:
    apt-get install libnagios-plugin-perl

    On other distros, you might use CPAN:

    perl -MCPAN -e 'install Nagios::Plugin'

    This will ask you lots of questions and install lots of dependencies (where you should say “yes”).

  6. Configure the check_memory command. To do this, create a file /etc/nagios-plugins/config/memory.cfg with this content:
    # 'check_memory' command definition
    define command{
            command_name    check_memory
            command_line    perl /usr/lib/nagios/plugins/check_memory.pl -w $ARG1$ -c $ARG2$
            }
  7. Now you can use the check_memory command to define a service. For example, add this to /etc/icinga/objects/localhost_icinga.cfg (assuming you define localhost-services there):
    define service{
            use                             generic-service
            host_name                       localhost
            service_description             Memory
            check_command                   check_memory!50%!25%
            }

    This will send you a warning when memory usage is 50% and critical when only 25% is free. You might want to adjust these values of course depending on what is normal on your system and how early you want to be notified.

  8. Check your configuration:
    /usr/local/icinga/bin/icinga -v /etc/icinga/icinga.cfg
  9. Restart Icinga / Nagios if the preflight-check was okay:
    /etc/init.d/icinga restart

This should be it.

I hope this helped somebody.

To monitor memory usage of a remote server, you’ll need SNMP for example. Maybe I’ll post another blog post on this soon.

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14. February 2012

Horde language selection does not work

Filed under: Linux,Server Administration — Tags: , , , , , , , , — Christopher Kramer @ 13:22

When selecting a language at login, Horde webmailer does not change the language?

Here is what I found out what helps:

On Debian, run the following command:

dpkg-reconfigure locales

Then select the correct languages. I had only selected the UTF8 languages for German, but Horde needs the following ones:

de_DE ISO-8859-1
de_DE@euro ISO-8859-15

If you have the problem with another language, select the corresponding language.

On Ubuntu, the chosen languages are stored here:

/var/lib/locales/supported.d/

I had a file named “de” in there where my chosen languages where listed and I added the ISO-versions above. You can find all supported languages here:

less /usr/share/i18n/SUPPORTED

On Ubuntu, after you included your languages, you have to run the following command:

dpkg-reconfigure locales

Afterwards, you need to restart apache:

apache2ctl -k graceful

That’s the smoothest way. In case it does not work, use one of those:

apache2ctl restart
service apache2 restart
/etc/init.d/apache2 restart

Now refresh Horde and everything should work.

Another problem is the following: if you chose a language in your Horde settings (login, Global Options, Locale and time, Select your preferred language), this overwrites the language you chose on login. So select “default” there to be able to chose language on login.

Hope this helps somebody.

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