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.. _tutorials:
*****************************
First steps with nagiosplugin
*****************************
This tutorial will guide you through all important steps of writing a check with
the :py:mod:`nagiosplugin` class library. Read this to get started.
Key concepts
============
:py:mod:`nagiosplugin` has a fine-grained class model with clear separation of
concerns. This allows plugin writers to focus on one
particular tasks at a time while writing plugins. Nagios/Icinga plugins need to
perform three step: data :term:`acquisition`, :term:`evaluation`, and
:term:`presentation`. Each step has an associated class (Resource, Context,
Summary) and information between tasks is passed with structured value objects
(Metric, Result).
Classes overview
================
Here is a diagram with the most important classes and their relationships::
+----------+ \
| Resource | |
+----------+ |
_____/ | \_____ | Acquisition
v v v |
+---------+ +---------+ +---------+ |
| Metric |...| Metric |...| Metric | <
+---------+ +---------+ +---------+ |
| | | |
v v v |
+---------+ +---------+ +---------+ |
| Context |...| Context |...| Context | | Evaluation
+---------+ +---------+ +---------+ |
| | | |
v v v |
+---------+ +---------+ +---------+ |
| Result |...| Result |...| Result | <
+---------+ +---------+ +---------+ |
\___ | ___/ |
v v v | Presentation
+---------+ |
| Summary | |
+---------+ /
Resource
A model of the thing being monitored. It should usually have the same name
as the whole plugin. Generates one or more metrics.
*Example: system load*
Metric
A single measured data point. A metric consists of a name, a value, a unit,
and optional minimum and maximum bounds. Most metrics are scalar (the value
can be represented as single number).
*Example: load1=0.75*
Context
Additional information to evaluate a metric. A context has usually a warning
and critical range which allows to determine if a given metric is OK or not.
Contexts also include information on how to present a metric in a
human-readable way.
*Example: warning=0.5, critical=1.0*
Result
Product of a metric and a context. A result consists of a state ("ok",
"warning", "critical", "unknown"), some explanatory text, and references to
the objects that it was generated from.
*Example: WARNING - load1 is 0.75*
Summary
Condenses all results in a single status line. The status line is the
plugin's most important output: it appears in mails, text messages,
pager alerts etc.
*Example: LOAD WARNING - load1 is 0.75 (greater than 0.5)*
The following tutorials which will guide you through the most important
features of :mod:`nagiosplugin`.
.. hint::
Study the source code in the :file:`nagiosplugin/examples` directory for
complete examples.
Tutorials
=========
.. toctree::
check_world
check_load
check_users
.. vim: set spell spelllang=en:
|
