Nagios Remote Plugin Executor (NRPE)

Resources to create a Docker image of the Nagios NRPE used for monitoring the Labs workbench infrastructure.

Prerequisites

To build:

• Docker

To run:

• A remote machine's credentials: username / ssh key / hostname
• Kubernetes

Build

The usual docker build command:

docker build -t ndslabs/nagios-nrpe:latest .

Run

Modify nagios-nrpe.yaml to adjust image to point to your own, and then run:

kubectl create -f nagios-nrpe.yaml

NOTE: This will start a DaemonSet for the NRPE container, which will run a copy on each node in the cluster.

Via Docker

docker run --privileged -v /:/mnt/ROOT --rm --name nrpe -p 5666:5666 ndslabs/nagios-nrpe

Configure NAGIOS to include the cluster in its checks

Then, you'll need to SSH into your NAGIOS instance and add this cluster to the list of "servers":

sudo su -
cd /usr/local/nagios/etc/servers
cp cwtest.cfg yourcluster.cfg
# Modify yourcluster.cfg to your liking
cat /home/nagios/.ssh/id_rsa.pub

Intracluster Configuration

Once NRPE is running and you've retrieved the public key for the nagios user, you will need to create a nagios user on your local node and add the SSH key from your NAGIOS monitor to ~/.ssh/authorized_keys:

sudo useradd -m -d /home/nagios nagios
sudo passwd nagios (value doesn't matter)
sudo vi /home/nagios/.ssh/authorized_keys
# paste value from nagios id_rsa.pub
chmod 600 /home/nagios/.ssh/authorized_keys

NOTE: Make sure /home/nagios and home/nagios/.ssh are owned by nagios:nagios with correct permissions

Testing Everything

1. From the NAGIOS server, confirm that you can SSH from the monitor to the target node without using a password:

sudo su - nagios
ssh nagios@yourserver
# Should SSH without password from nagios user to nagios user

2. Open browser to http://NAGIOS_MONITOR_HOSTNAME/nagios
3. Find your server. Service status should be pending. Wait until OK.