CentOS Nagios Dockerfile with a start script

31 July 2018

Here is a short Dockerfile that can set up a CentOS + Nagios + Apache instance in few minutes inside a container.

Of course one can always prefer to work with an image instead, however Dockerfiles have proven to be more secure, clear, and easy to change or follow.

Keep in mind to change the version of Nagios to the latest one:


#===========================
# Dockerfile based on
# centos latest
#===========================


FROM centos:latest
LABEL project="Nagios" \
      author="Veselin Vasilev" \
      image_name="nagios"

RUN yum update -y 
RUN yum install -y epel-release \
   gcc \
   glibc \
   glibc-common \
   wget \
   unzip \
   httpd \
   php \
   gd \
   gd-devel \
   perl \
   postfix \
   make

RUN wget -O /tmp/nagioscore.tar.gz https://github.com/NagiosEnterprises/nagioscore/archive/nagios-4.4.1.tar.gz
WORKDIR /tmp/
RUN tar xzf nagioscore.tar.gz

WORKDIR /tmp/nagioscore-nagios-4.4.1/
RUN ./configure
RUN make all


RUN make install-groups-users
RUN usermod -a -G nagios apache 
RUN make install

RUN make install-daemoninit
RUN systemctl enable httpd.service

RUN make install-commandmode
RUN make install-config
RUN make install-webconf

RUN htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin 

RUN yum install -y which \
  gettext \
  automake \
  autoconf \
  openssl-devel \
  net-snmp \
  net-snmp-utils

RUN yum install -y perl-Net-SNMP

WORKDIR /tmp
RUN wget --no-check-certificate -O /tmp/nagios-plugins.tar.gz https://github.com/nagios-plugins/nagios-plugins/archive/release-2.2.1.tar.gz
RUN tar zxf nagios-plugins.tar.gz

WORKDIR /tmp/nagios-plugins-release-2.2.1/
RUN ./tools/setup
RUN ./configure
RUN make
RUN make install

# Create a start script
# Keep in mind that systemd magic wont work inside a container without privilege  
# therefore we need this custom start of Nagios and Apache within the container  
RUN echo "#!/bin/bash" >> /opt/start.sh
RUN echo "/etc/rc.d/init.d/nagios start" >> /opt/start.sh
RUN echo "/usr/sbin/httpd -k start" >> /opt/start.sh
RUN echo "tail -f /var/log/httpd/access_log /var/log/httpd/error_log" >> /opt/start.sh
RUN echo >> /opt/start.sh
RUN chmod +x /opt/start.sh

#Perform some cleanup
RUN  yum erase gcc \
   glibc \
   glibc-common

ENTRYPOINT ["/opt/start.sh"]

Do not forget to tag your newly created image


sudo docker tag 2405388255f0 nagios:latest

Here is how to run the container out of the image that has been created, this can be setup to map a host directory for the purpose of Nagios configs, and etc:


sudo docker run --name centos_nagios_container -dti -p 50443:443 -p 50080:80 nagios:latest

If container is ran with the command above, the installation can be tested by accessing the following URL (from the host where the container is running):


http://localhost:50080/nagios/

Useful sources:
CentoOS Nagios setup
Docker Reference

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