== Create own docker image and save it to our repository. ==
(install nagios server in docker image and save the image to the repository)

Firstly, you need to have docker installed.

Then:

docker images (list  to make sure you have the centos 6.8 OS images)
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
centos              6.8                 c4cdd30c384d        5 weeks ago         194.5 MB

docker run -it --net=host c4cdd30c384d /bin/bash (it will run the docker 6.8 image)

==============================================================

The above could be ignored if you install nagios server on a physical or virtual machine and you do not want to use docker.

Install and Configure the Nagios Server:

{{{
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
yum install nagios nagios-plugins-all nagios-plugins-nrpe nrpe php httpd
chkconfig httpd on
chkconfig nagios on
service httpd start
service nagios start

htpasswd -c /etc/nagios/passwd nagiosadmin
}}}
Now you can navigate over to your droplet's IP address '''http://IP/nagios''' and login.

You will be prompted for password you set in previous step.