Nagios is an open source monitoring tool that has been available since 1999. It is commonly used to monitor servers, services, and applications. The document discusses how to install and configure Nagios on various platforms like CentOS, Ubuntu, and Mac OS X. It also provides examples of how to monitor common services like HTTP, MySQL, disk space, and custom applications using Nagios plugins. Graphing and alerting capabilities are discussed as well. The presentation concludes with a demonstration and Q&A section.

1. Nagios for WO systems
Pascal Robert
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2. Nagios
• Open source project
• Available since 1999 (Netsaint)
• Pretty much the standard
• Interface a bit old (frames!)

3. Installation
• CentOS/Amazon Linux:
yum install nagios nagios-plugins-all
• Ubuntu:
apt-get install nagios3
• Mac OS X:
port install nagios

4. Configuration directory
• CentOS/Amazon Linux:
/etc/nagios
/etc/httpd/conf.d/nagios.conf
• Ubuntu:
/etc/nagios3
• Mac OS X:
/opt/local/etc/nagios

5. NRPE
• Agent to check local services
• CentOS/AmazonLinux:
Installation: yum install nrpe
Configuration: /etc/nagios/nrpe.cfg
• Ubuntu:
apt-get install nagios-nrpe-server
Configuration: /etc/nagios/nrpe.cfg
• Mac OS X:
port install nrpe
Configuration: /opt/local/etc/nrpe.cfg.sample

6. Basic monitoring

7. HTTP
• check_http plugin
• Can check port, string in respond, path, etc.
• Can do POST request with content
• Can do GET, HEAD, OPTIONS,TRACE, DELETE requests
• Can do BASIC auth

8. HTTPS
• Same plugin as HTTP
• Can check date of certificate

9. Using Selenium WebDriver
• Need more complex HTTP check?
• Selenium WebDriver + Google Chrome + script to the rescue!

10. MySQL
• Two plugins: check_mysql and check_mysql_query
• check_mysql can check status of slave
• check_mysql_query will check result of query against warning/
critical levels

11. PostgreSQL
• check_pgsql
• Will check if specified database is active and running

12. Disk
• You don’t want to run out of disk space!
• check_disk plugin
• Check available disk space of specific file system or path

13. JMX
• Check the heap space of your WO apps!
• check_jmx
• http://exchange.nagios.org/directory/Plugins/Java-Applications-
and-Servers/check_jmx/details

14. check_woapp.py
• Nagios plugin (Python) that checks numerous stuff in Monitor
• State
• Number of deaths
• Is refusing new sessions
• Is auto recover on?
• # of active sessions

15. Plugin development
• Can be anything! Bash, Python, Perl, Java, etc.
• Only need to send proper exit() signal
• Better to send performance data too

16. Other useful plugins
• check_load
• check_by_ssh
• check_dns
• check_file_age
• check_tcp/check_udp
• check_linux_raid
• check_ntp_time
• check_swap

17. Graphing
• Not built-in
• Numerous third-party
• I use PNP4Nagios

18. Actions
• Can launch actions (scripts) based on events
• Nagios call this « event handlers »
• Examples:
• Start new instance if one is down
• Start newVM if host memory is low

19. Demo

20. Next: Logstash

21. Q&A