notss-eh

notss-eh - A not so simple event-handler for Nagios

notss-eh

A Not So Simple Event-Handler for Nagios

Overview

The notss-eh script is a flexible event-handler for Nagios-compatible monitoring systems. It's designed to keep execution logic and action execution separate - this gives you the option to use different "execution modules" or add your own.

Currently it supports executing NRPE, SSH and local shell commands, but more modules are planned like SNMP sets, VMWare commands and similar!

Features

  • Action execution on specified check attempt or soft state changes
  • Supports execution of multiple actions on state changes
  • Merlin check source detection using the "mon" command (useful in peered setups)
  • Easy to extend with new "execution modules"
  • Resonable logging to syslog or stdout

Execution modules

  • NRPE

    • Executes NRPE commands with the "check_nrpe" plugin
    • Supports result status verification
    • Dependencies: None
  • SSH

    • Executes commands over SSH
    • Supports key and password authentication
    • Dependencies: paramiko
    • Notes: Paramiko (the Python SSH module) seems to have some problems with ECDSA host keys (https://github.com/paramiko/paramiko/issues/243). A work-around is to connect with "ssh -o HostKeyAlgorithms='ssh-rsa' user@host" when adding the host to "known_hosts".
  • Shell
    • Executes local shell commands
    • Supports executing command with different shells
    • Can verify the return code of the executed commands
    • Supports muting shell command output in event handler logs
    • Dependencies: None

Installation and configuration

The main parts of the script uses nothing outside the Python 2.7 standard library (if you use it on EL6 you may need to install the "argparse" module), but the execution modules might have their own.

Download the "notss-eh.py" and place it in a suitable directory on the monitoring system(s). Some of the parameters should be set with Nagios macros - below is an example command configuration:

# Using notss-eh with source checking to execute NRPE commands without session encryption
command_name: notss-eh-hard_checksrc-nrpe_insecure
command_line: $USER1$/custom/notss-eh.py --host "$HOSTADDRESS$" --name "$HOSTNAME$" --description "$SERVICEDESC$" --state "$SERVICESTATE$" --state-type "$SERVICESTATETYPE$" --attempt "$SERVICEATTEMPT$" --ok "$ARG1$" --warning "$ARG2$" --critical "$ARG3$" --unknown "$ARG4$" -C -l syslog nrpe --insecure
# Using notss-eh with source checking to execute local shell command with return code checking
command_name: notss-eh-hard_checksrc-shell
command_line: $USER1$/custom/notss-eh.py --host "$HOSTADDRESS$" --name "$HOSTNAME$" --description "$SERVICEDESC$" --state "$SERVICESTATE$" --state-type "$SERVICESTATETYPE$" --attempt "$SERVICEATTEMPT$" --ok "$ARG1$" --warning "$ARG2$" --critical "$ARG3$" --unknown "$ARG4$" -C -l syslog shell --returncode 0

To use it with a service, set the proper arguments for the event handler - you can use the "skip" keyword to ignore action specified states like "OK" or "WARNING".