Bash Script for Nagios to Check Status of Docker Container

check_docker_container.sh

#!/bin/bash

# Author: Erik Kristensen
# Email: [email protected]
# License: MIT
# Nagios Usage: check_nrpe!check_docker_container!_container_id_
# Usage: ./check_docker_container.sh _container_id_
#
# Depending on your docker configuration, root might be required. If your nrpe user has rights
# to talk to the docker daemon, then root is not required. This is why root privileges are not
# checked.
#
# The script checks if a container is running.
#   OK - running
#   WARNING - restarting
#   CRITICAL - stopped
#   UNKNOWN - does not exist
#
# CHANGELOG - March 20, 2017
#  - Removes Ghost State Check, Checks for Restarting State, Properly finds the Networking IP addresses
#  - Returns unknown (exit code 3) if docker binary is missing, unable to talk to the daemon, or if container id is missing

CONTAINER=$1

if [ "x${CONTAINER}" == "x" ]; then
  echo "UNKNOWN - Container ID or Friendly Name Required"
  exit 3
fi

if [ "x$(which docker)" == "x" ]; then
  echo "UNKNOWN - Missing docker binary"
  exit 3
fi

docker info > /dev/null 2>&1
if [ $? -ne 0 ]; then
  echo "UNKNOWN - Unable to talk to the docker daemon"
  exit 3
fi

RUNNING=$(docker inspect --format="{{.State.Running}}" $CONTAINER 2> /dev/null)

if [ $? -eq 1 ]; then
  echo "UNKNOWN - $CONTAINER does not exist."
  exit 3
fi

if [ "$RUNNING" == "false" ]; then
  echo "CRITICAL - $CONTAINER is not running."
  exit 2
fi

RESTARTING=$(docker inspect --format="{{.State.Restarting}}" $CONTAINER)

if [ "$RESTARTING" == "true" ]; then
  echo "WARNING - $CONTAINER state is restarting."
  exit 1
fi

STARTED=$(docker inspect --format="{{.State.StartedAt}}" $CONTAINER)
NETWORK=$(docker inspect --format="{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}" $CONTAINER)

echo "OK - $CONTAINER is running. IP: $NETWORK, StartedAt: $STARTED"

Hello guys.
Added nagios user to docker group, so it has permissions to speak to docker daemon.
When I execute it as nagios:

nagios@nrpe-client-host:~$ sh /usr/lib/nagios/plugins/check_docker_container.sh redis
/usr/lib/nagios/plugins/check_docker_container.sh: 25: [: xredis: unexpected operator
/usr/lib/nagios/plugins/check_docker_container.sh: 30: [: x/usr/bin/docker: unexpected operator
/usr/lib/nagios/plugins/check_docker_container.sh: 48: [: true: unexpected operator
/usr/lib/nagios/plugins/check_docker_container.sh: 55: [: false: unexpected operator
OK - redis is running. IP: 172.17.0.2, StartedAt: 2018-03-01T08:07:42.857992735Z

So, it works.
But when I'm trying to execute it from nagios host:

user@nagios-host:~$ /usr/local/nagios/libexec/check_nrpe -H 123.45.67.89 -c check_docker_container redis
NRPE: Unable to read output

Nagios displays the same "UNKNOWN - NRPE: Unable to read output"

Here is nrpe.cfg
command[check_docker_container]=/usr/lib/nagios/plugins/check_docker_container.sh
and service definition

define service {
        use                             generic-service
        host_name                       host-example
        service_description             Redis Docker Container
        check_command                   check_nrpe!check_docker_container!redis
}

Am I missing something? What's wrong?
Thank you!

Just solved my issue.
It was about permissions, sorry.
Great script, btw. Thanks.

@wirtoo can you share the permission issue fix you used?

I'm running NRPE in a container. Do I need to add the nagios user to /etc/sudoers in the container itself?
From my Nagios host:

./check_nrpe -H 10.99.125.131 -c check_docker_container1
NRPE: Unable to read output

What I do wrong?

Remote
/usr/local/nagios/libexec/check_nrpe -H hostip -c check_docker -a asterisk
UNKNOWN - Missing docker binary

Local
/usr/lib64/nagios/plugins/check_docker asterisk
OK - asterisk is running. IP: 172.19.0.2, StartedAt: 2018-09-14T06:44:09.174409454Z

I understand this might be outdated, I mean this thread not the script. Take a look here and it may help some of you who are having permission problems. Nagios and Docker Monitoring

Awesome script, thank you, just what I needed!

HI,

i need docker stat output with mail alert shell script. Please help on this

Thank you for sharing this!

Thank you Erik Kristensen

Thanks a lot, this is also working for PRTG (with some small changes in the output).