Nagios is a powerful tool that allows you to monitor just about anything. It’s so easy to even take existing legacy system and adapt it to work with Nagios. When I came across kingkiwix and his blog here I wanted to repackage the content in a more user-friendly way for sharing. I wanted a solution that didn’t require me to pull in a bunch of development libraries and compilers. I also wanted a solution that I could re-use on other systems through a version controlled and packaged interface.
RPMs provide a version control and an automated set of scripts to configure the system how I want it. The beauty of them is that if you disagree with
something the tool you’re packaging does, you can feed RPMs patch files to accommodate it without obstructing the original authors intention.
Now I won’t lie and claim I wrote these SPEC files from scratch because I certainly didn’t. I took the stock ones that ship with both products (both Nagios and Nagios-Plugins) and modified them significantly to accommodate and satisfy my compulsive needs.
My needs required a bit more automation in the setup as well as including:
The use of nagiocmd user group.
A /etc/nagios/conf.d directory to behave similar to how Apache works. I want to be able to drop configuration files into here and just have it work without re-adjusting configuration files.
Alerting Apache on new updates/installs so just installing the package alone is all you need to do.
Nagios Plugins should work right away once they are installed.
Nagios Plugins and permissions should adapt to the new nagiocmd user and place in a common directory Nagios was already configured to look in.
Nagios Plugins has to many dependencies; I wanted to break this up into separate packages for those who needed them. For example, I don’t use MySQL at all; so why should I need the MySQL Libraries installed on my system just to use Nagios Plugins.
Nagios group permissions added to /etc/nagios directory for people using third party management applications. Just add any third party app to the Nagios group and they’ll be able to manage your configuration too:
1
2
3
# substitute <3rdpartyid> for the actual group/id belonging
Visiting http://localhost/nagios/ should look similar to this if you followed the steps correctlyYes, that’s right… you’re done! You can access your Nagios Web Interface by visiting http://localhost/nagios. How you configure your system further is beyond the scope of this tutorial/blog. My goal was just to get you started with an out of the box working Nagios solution :).
If your not already familiar with Nagios, you may want to read the documentation so you can monitor more then just the 8 example checks it sets up for you out of the box. There are also some great web configuration tools you can check out as well here.
Package Information
Software installs to: /usr/share/nagios
Plugins install to: /usr/lib64/nagios/plugins. Keep in mind I packaged everything in such a way that compiling it for 32-bit will work fine. In which case you’ll find plugins installed to: /usr/lib/nagios/plugins
Website is accessible at: http://localhost/nagios/ out of the box, but you can adjust it’s web configuration by adjusting /etc/httpd/conf.d/nagios.conf to your likings.
Nagios Core 4 configuration file can be found at: /etc/nagios/nagios.cfg and a newly added /etc/nagios/conf.d/ directory has been added to make some things easier to add/remove later.
1
2
3
# SELinux Users may wish to turn this flag on if they intend to allow it
# to call content as root (using sudo) which it must do for some status checks.
setsebool -P nagios_run_sudo on
I want to repackage this myself
All of my blogs provide a way to build everything from scratch yourself for those who don’t want to just download the binary packages and roll with them. I use mock for everything I build so I don’t need to haul in development packages into my native environment. You’ll need to make sure mock is setup and configured properly first for yourself:
1
2
3
4
5
6
7
8
# Install 'mock' into your environment if you don't have it already.
# This step will require you to be the superuser (root) in your native
# environment.
yum install-y mock
# Grant your normal every day user account access to the mock group
# This step will also require you to be the root user.
usermod-a -G mock YourNonRootUsername
At this point it’s safe to change from the ‘root‘ user back to the user account you granted the mock group privileges to in the step above. We won’t need the root user again until the end of this tutorial when we install our built RPM.
001
002
003
004
005
006
007
008
009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
037
038
039
040
041
042
043
044
045
046
047
048
049
050
051
052
053
054
055
056
057
058
059
060
061
062
063
064
065
066
067
068
069
070
071
072
073
074
075
076
077
078
079
080
081
082
083
084
085
086
087
088
089
090
091
092
093
094
095
096
097
098
099
100
101
102
103
104
105
106
107
108
109
110
111
112
113
# Perhaps make a directory and work within it so it's easy to find
# everything later
mkdirnagiosbuild
cdnagiosbuild
###
# Now we want to download all the requirements we need to build
# *Note that all the commands that interact with mock I pass in
# the -v which outputs a lot of verbose information. You don't
# have to supply it; but I like to see what is going on at times.
# **Note: You may receive this warning when calling the '--copyout'
# above:
# WARNING: unable to delete selinux filesystems
# (/tmp/mock-selinux-plugin.??????): #
# [Errno 1] Operation not permitted: '/tmp/mock-selinux-plugin.??????'
#
# This is totally okay; and is safe to ignore, the action you called
# still worked perfectly; so don't panic :)
Considerations
If you take Nagios seriously, you will really want to consider expanding it to support one (or all) of the following addons:
NRPE – Nagios Remote Plugin ExecutorNRPE – Nagios Remote Plugin Executor
NRPE is an addon that allows you to execute plugins on remote Linux/Unix hosts. This is useful if you need to monitor local resources/attributes like disk usage, CPU load, memory usage, etc. on a remote host. Similar functionality can be accomplished by using the check_by_ssh plugin, although it can impose a higher CPU load on the monitoring machine – especially if you are monitoring hundreds or thousands of hosts.
NSCA – Nagios Service Check AcceptorNSCA – Nagios Service Check Acceptor
NSCA is an addon that allows you to send passive check results from remote Linux/Unix hosts to the Nagios daemon running on the monitoring server. This is very useful in distributed and redundant/failover monitoring setups.
I’m considering packaging these as well to conform with the packages I’ve already provided here, but I’ll do that in another blog some other time if there ends up being a demand for it .
