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-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V4.1//EN" >
<book>
<title>Nagios Plug-in Developer Guidelines</title>
<bookinfo>
<authorgroup>
<author>
- <firstname>Karl</firstname>
- <surname>DeBisschop</surname>
- <affiliation>
- <address><email>karl@debisschop.net</email></address>
- </affiliation>
+ <affiliation>
+ <orgname>Nagios Plugins Development Team</orgname>
+ </affiliation>
</author>
-
- <author>
- <firstname>Ethan</firstname>
- <surname>Galstad</surname>
- <authorblurb>
- <para>Author of Nagios</para>
- <para><ulink url="http://www.nagios.org"></ulink></para>
- </authorblurb>
- <affiliation>
- <address><email>netsaint@linuxbox.com</email></address>
- </affiliation>
- </author>
-
- <author>
- <firstname>Hugo</firstname>
- <surname>Gayosso</surname>
- <affiliation>
- <address><email>hgayosso@gnu.org</email></address>
- </affiliation>
- </author>
-
-
- <author>
- <firstname>Subhendu</firstname>
- <surname>Ghosh</surname>
- <affiliation>
- <address><email>sghosh@sourceforge.net</email></address>
- </affiliation>
- </author>
-
- <author>
- <firstname>Stanley</firstname>
- <surname>Hopcroft</surname>
- <affiliation>
- <address><email>stanleyhopcroft@sourceforge.net</email></address>
- </affiliation>
- </author>
-
</authorgroup>
- <pubdate>2002</pubdate>
+ <pubdate>2005</pubdate>
<title>Nagios plug-in development guidelines</title>
<revhistory>
<revision>
- <revnumber>0.4</revnumber>
- <date>2 May 2002</date>
+ <revnumber>$Revision$</revnumber>
+ <date>$Date$</date>
</revision>
</revhistory>
<copyright>
- <year>2000 2001 2002</year>
- <holder>Karl DeBisschop, Ethan Galstad,
- Hugo Gayosso, Stanley Hopcroft, Subhendu Ghosh</holder>
+ <year>2000 - 2005</year>
+ <holder>Nagios Plugins Development Team</holder>
</copyright>
</bookinfo>
- <preface id=preface>
- <title>About the guidelines</title>
-
+<preface id="preface"><title>Preface</title>
<para>The purpose of this guidelines is to provide a reference for
the plug-in developers and encourage the standarization of the
different kind of plug-ins: C, shell, perl, python, etc.</para>
-
- <section> <title>Copyright</title>
-
- <para>Nagios Plug-in Development Guidelines Copyright (C) 2000 2001
- 2002
- Karl DeBisschop, Ethan Galstad, Hugo Gayosso, Stanley Hopcroft,
- Subhendu Ghosh</para>
+ <para>Nagios Plug-in Development Guidelines Copyright (C) 2000-2005
+ (Nagios Plugins Team)</para>
<para>Permission is granted to make and distribute verbatim
copies of this manual provided the copyright notice and this
permission notice are preserved on all copies.</para>
- <para>The plugins themselves are copyrighted by their respective
- authors.</para>
-
- </section>
+ <para>The plugins themselves are copyrighted by their respective
+ authors.</para>
</preface>
<article>
+<section id="DevRequirements"><title>Development platform requirements</title>
+ <para>
+ Nagios plugins are developed to the GNU standard, so any OS which is supported by GNU
+ should run the plugins. While the requirements for compiling the Nagios plugins release
+ is very small, to develop from CVS needs additional software to be installed. These are the
+ minimum levels of software required:
+
+ <literallayout>
+ gnu make 3.79
+ automake 1.8
+ autoconf 2.58
+ gettext 0.11.5
+ </literallayout>
+
+ To compile from CVS, after you have checked out the code, run:
+ <literallayout>
+ tools/setup
+ ./configure
+ make
+ make install
+ </literallayout>
+ </para>
+</section>
+
<section id="PlugOutput"><title>Plugin Output for Nagios</title>
<para>You should always print something to STDOUT that tells if the
- service is working or why its failing. Try to keep the output short -
+ service is working or why it is failing. Try to keep the output short -
probably less that 80 characters. Remember that you ideally would like
the entire output to appear in a pager message, which will get chopped
off after a certain length.</para>
when it notifies contacts about potential problems. If you print
multiple lines, you're out of luck. Remember, keep it short and
to the point.</para>
- </section>
+
+ <para>Output should be in the format:</para>
+ <literallayout>
+ SERVICE STATUS: Information text
+ </literallayout>
+ <para>However, note that this is not a requirement of the API, so you cannot depend on this
+ being an accurate reflection of the status of the service - the status should always
+ be determined by the return code.</para>
+ </section>
+
+ <section><title>Verbose output</title>
+ <para>Use the -v flag for verbose output. You should allow multiple
+ -v options for additional verbosity, up to a maximum of 3. The standard
+ type of output should be:</para>
+
+ <table id="verboselevels"><title>Verbose output levels</title>
+ <tgroup cols="2">
+ <thead>
+ <row>
+ <entry><para>Verbosity level</para></entry>
+ <entry><para>Type of output</para></entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry align="center"><para>0</para></entry>
+ <entry><para>Single line, minimal output. Summary</para></entry>
+ </row>
+ <row>
+ <entry align="center"><para>1</para></entry>
+ <entry><para>Single line, additional information (eg list processes that fail)</para></entry>
+ </row>
+ <row>
+ <entry align="center"><para>2</para></entry>
+ <entry><para>Multi line, configuration debug output (eg ps command used)</para></entry>
+ </row>
+ <row>
+ <entry align="center"><para>3</para></entry>
+ <entry><para>Lots of detail for plugin problem diagnosis</para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
<section><title>Screen Output</title>
<para>The plug-in should print the diagnostic and just the
crt (remember when fixing stuff in the server room!)</para>
</section>
- <section><title>Return the proper status code</title>
- <para>See <xref linkend="ReturnCodes"> below
- for the numeric values of status codes and their
- description. Remember to return an UNKNOWN state if bogus or
- invalid command line arguments are supplied or it you are unable
- to check the service.</para>
- </section>
-
<section><title>Plugin Return Codes</title>
<para>The return codes below are based on the POSIX spec of returning
a positive value. Netsaint prior to v0.0.7 supported non-POSIX
occurred and error code is 138 or 255 or some such number. These
are usually caused by plugins using system commands and having not
enough checks to catch unexpected output. Developers should include a
- default catch-all for system command output that returns an UNKOWN
+ default catch-all for system command output that returns an UNKNOWN
return code.</para>
<table id="ReturnCodes"><title>Plugin Return Codes</title>
</thead>
<tbody>
<row>
- <entry align=center><para>0</para></entry>
- <entry valign=middle><para>OK</para></entry>
+ <entry align="center"><para>0</para></entry>
+ <entry valign="middle"><para>OK</para></entry>
<entry><para>The plugin was able to check the service and it
appeared to be functioning properly</para></entry>
</row>
<row>
- <entry align=center><para>1</para></entry>
- <entry valign=middle><para>Warning</para></entry>
+ <entry align="center"><para>1</para></entry>
+ <entry valign="middle"><para>Warning</para></entry>
<entry><para>The plugin was able to check the service, but it
appeared to be above some "warning" threshold or did not appear
to be working properly</para></entry>
</row>
<row>
- <entry align=center><para>2</para></entry>
- <entry valign=middle><para>Critical</para></entry>
+ <entry align="center"><para>2</para></entry>
+ <entry valign="middle"><para>Critical</para></entry>
<entry><para>The plugin detected that either the service was not
running or it was above some "critical" threshold</para></entry>
</row>
<row>
- <entry align=center><para>3</para></entry>
- <entry valign=middle><para>Unknown</para></entry>
+ <entry align="center"><para>3</para></entry>
+ <entry valign="middle"><para>Unknown</para></entry>
<entry><para>Invalid command line arguments were supplied to the
- plugin or the plugin was unable to check the status of the given
- hosts/service</para></entry>
+ plugin or low-level failures internal to the plugin (such as unable to fork,
+ or open a tcp socket) that prevent it from performing the specified
+ operation. Higher-level errors (such as name resolution errors,
+ socket timeouts, etc) are outside of the control of plugins and should
+ generally NOT be reported as UNKNOWN states.
+ </para></entry>
</row>
</tbody>
</tgroup>
</section>
+ <section id="thresholdformat"><title>Threshold range format</title>
+ <para>Thresholds ranges define the warning and critical levels for plugins to
+ alert on. The theory is that the plugin will do some sort of check which returns
+ back a numerical value, or metric, which is then compared to the warning and
+ critical thresholds.
+ This is the generalised format for threshold ranges:</para>
+ <literallayout>
+ [@]start:end
+ </literallayout>
+
+ <para>Notes:</para>
+ <orderedlist>
+ <listitem><para>start > end</para>
+ </listitem>
+ <listitem><para>start and ":" is not required if start=0</para>
+ </listitem>
+ <listitem><para>if range is of format "start:" and end is not specified,
+ assume end is infinity</para>
+ </listitem>
+ <listitem><para>to specify negative infinity, use "~"</para>
+ </listitem>
+ <listitem><para>alert is raised if metric is outside start and end range
+ (inclusive of endpoints)</para>
+ </listitem>
+ <listitem><para>if range starts with "@", then alert if inside this range
+ (inclusive of endpoints)</para>
+ </listitem>
+ </orderedlist>
+
+ <para>Note: Not all plugins are coded to expect ranges in this format. It is
+ planned for a future release to
+ provide standard libraries to parse and compare metrics against ranges. There
+ will also be some work in providing multiple metrics.</para>
+ </section>
+
+ <section><title>Performance data</title>
+ <para>Performance data is defined by Nagios as "everything after the | of the plugin output" -
+ please refer to Nagios documentation for information on capturing this data to logfiles.
+ However, it is the responsibility of the plugin writer to ensure the
+ performance data is in a "Nagios plugins" format.
+ This is the expected format:</para>
+
+ <literallayout>
+ 'label'=value[UOM];[warn];[crit];[min];[max]
+ </literallayout>
+
+ <para>Notes:</para>
+ <orderedlist>
+ <listitem><para>space separated list of label/value pairs</para>
+ </listitem>
+ <listitem><para>label can contain any characters</para>
+ </listitem>
+ <listitem><para>the single quotes for the label are optional. Required if
+ spaces, = or ' are in the label</para>
+ </listitem>
+ <listitem><para>label length is arbitrary, but ideally the first 19 characters
+ are unique (due to a limitation in RRD). Be aware of a limitation in the
+ amount of data that NRPE returns to Nagios</para>
+ </listitem>
+ <listitem><para>to specify a quote character, use two single quotes</para>
+ </listitem>
+ <listitem><para>warn, crit, min or max may be null (for example, if the threshold is
+ not defined or min and max do not apply). Trailing unfilled semicolons can be
+ dropped</para>
+ </listitem>
+ <listitem><para>min and max are not required if UOM=%</para>
+ </listitem>
+ <listitem><para>value, min and max in class [-0-9.]. Must all be the
+ same UOM</para>
+ </listitem>
+ <listitem><para>warn and crit are in the range format (see
+ <xref linkend="thresholdformat">). Must be the same UOM</para>
+ </listitem>
+ <listitem><para>UOM (unit of measurement) is one of:</para>
+ <orderedlist>
+ <listitem><para>no unit specified - assume a number (int or float)
+ of things (eg, users, processes, load averages)</para>
+ </listitem>
+ <listitem><para>s - seconds (also us, ms)</para></listitem>
+ <listitem><para>% - percentage</para></listitem>
+ <listitem><para>B - bytes (also KB, MB, TB)</para></listitem>
+ <listitem><para>c - a continous counter (such as bytes
+ transmitted on an interface)</para></listitem>
+ </orderedlist>
+ </listitem>
+ </orderedlist>
+
+ <para>It is up to third party programs to convert the Nagios plugins
+ performance data into graphs.</para>
+ </section>
+
+ <section><title>Translations</title>
+ <para>If possible, use translation tools for all output to respect the user's language
+ settings. See <xref linkend="translations_developers"> for guidelines
+ for the core plugins.
+ </para>
+ </section>
</section>
<section id="SysCmdAuxFiles"><title>System Commands and Auxiliary Files</title>
<orderedlist>
<listitem><para> Do not use BEGIN and END blocks since they will be called
- the first time and when Nagios shuts down with Embedded Perl (ePN). In
+ only once (when Nagios starts and shuts down) with Embedded Perl (ePN). In
particular, do not use BEGIN blocks to initialize variables.</para>
</listitem>
<listitem><para>To use utils.pm, you need to provide a full path to the
- module in order for it to work with ePN.</para>
+ module in order for it to work.</para>
<literallayout>
e.g.
variable. </para>
- <para>Explicitly initialize each varialable in use. Otherwise with
- caching enabled, the plugin will not be recompilied each time, and
+ <para>Explicitly initialize each variable in use. Otherwise with
+ caching enabled, the plugin will not be recompiled each time, and
therefore Perl will not reinitialize all the variables. All old
variable values will still be in effect.</para>
</listitem>
- <listitem><para>Do not use < DATA > (these simply do not compile under ePN).</para>
+ <listitem><para>Do not use >DATA< handles (these simply do not compile under ePN).</para>
</listitem>
- <listitem><para>Do not use named subroutines</para>
+ <listitem><para>Do not use global variables in named subroutines. This is bad practise anyway, but with ePN the
+ compiler will report an error "<global_var> will not stay shared ..". Values used by
+ subroutines should be passed in the argument list.</para>
</listitem>
<listitem><para>If writing to a file (perhaps recording
performance data) explicitly close close it. The plugin never
- calls <emphasis role=strong>exit</emphasis>; that is caught by
+ calls <emphasis role="strong">exit</emphasis>; that is caught by
p1.pl, so output streams are never closed.</para>
</listitem>
<listitem><para>As in <xref linkend="runtime"> all plugins need
to monitor their runtime, specially if they are using network
- resources. Use of the <emphasis>alarm</emphasis> is recommended.
+ resources. Use of the <emphasis>alarm</emphasis> is recommended
+ noting that some Perl modules (eg LWP) manage timers, so that an alarm
+ set by a plugin using such a module is overwritten by the module.
+ (workarounds are cunning (TM) or using the module timer)
Plugins may import a default time out ($TIMEOUT) from utils.pm.
</para>
</listitem>
<section><title>Option Processing</title>
<para>For plugins written in C, we recommend the C standard
- getopt library for short options. If using getopt_long, check to
- be sure that HAVE_GETOPT_H is defined (configure checks this and
- sets the #define in common/config.h).</para>
+ getopt library for short options. Getopt_long is always available.
+ </para>
<para>For plugins written in Perl, we recommend Getopt::Long module.</para>
-w warning threshold (--warning)
-c critical threshold (--critical)
-H hostname (--hostname)
+ -v verbose (--verbose)
</literallayout>
<para>In addition to the reserved options above, some other standard options are:</para>
help. Help text should fit on an 80-character width display, but
may run as many lines as needed.</para>
+ <para>The option -v or --verbose should be present in all plugins.
+ The user should be allowed to specify -v multiple times to increase
+ the verbosity level, as described in <xref linkend="verboselevels">.</para>
</section>
<section>
<para>Old style was to do things like -ct for critical time and
-cv for critical value. That goes out the window with POSIX
- getopt. The allowable alternatves are:</para>
+ getopt. The allowable alternatives are:</para>
<orderedlist>
<listitem>
<para>As always, comments are welcome - making this consistent
without a host of long options was quite a hassle, and I would
- suspect that there are flaws in this strategy. Perhaps clear
- long-options is the most important of the above choices, but not
- all POSIX systems have C libraries for long options, so the
- short forms must exist as well.</para>
+ suspect that there are flaws in this strategy.
+ </para>
</section>
</section>
-<section id="SubmittingChanges"><title>New submissions and patches</title>
+<section id="Testcases"><title>Test cases</title>
+<para>
+Tests are the best way of knowing if the plugins work as expected. Please
+create and update test cases where possible.
+</para>
+
+<para>
+To run a test, from the top level directory, run "make test". This will run
+all the current tests and report an overall success rate.
+</para>
+
+<para>
+See the <ulink url="http://tinderbox.altinity.org">Nagios Plugins Tinderbox server</ulink>
+for the daily test results.
+</para>
+
+<section><title>Test cases for plugins</title>
+<para>These use perl's Test::More. To do a one time test, run "cd plugins && perl t/check_disk.t".
+</para>
+
+<para>There will somtimes be failures seen in this output which are known failures that
+need to be fixed. As long as the return code is 0, it will be reported as "test pass".
+(If you have a fix so that the specific test passes, that will be gratefully received!)
+</para>
+
+<para>
+If you want a summary test, run: "cd plugins && perl -MTest::Harness -e 'runtests(@ARGV)' t/check_disk.t".
+This runs the test in a summary format.
+</para>
+
+<para>
+For a good and amusing tutorial on using Test::More, see this
+<ulink url="http://search.cpan.org/~mschwern/Test-Simple-0.62/lib/Test/Tutorial.pod">
+link</ulink>
+</para>
- <para>If you would like other to use your plugins and have it included in
- the standard distribution, please include patches for the relavant
- configuration files, in particular "configure.in" Otherwise submitted
- plugins will be included in the contrib directory.</para>
-
- <para>Plugins in the contrib directory are going to be migrated to the
- standard plugins/plugin-scripts directory as time permits and per user
- requests</para>
+</section>
- <para>Patches should be submitted via the SourceForge and be announced to
- the mailing list.</para>
-
- <para>For new plugins, provide a diff to add to the EXTRAS list (configure.in)
- unless you are fairly sure that the plugin will work for all platforms with
- no non-standard software added.</para>
+<section><title>Testing the C library functions</title>
+<para>
+Will be looking at using libtap, which is utilised by the FreeBSD team. The output is
+based on perl's TAP (Test Anything Protocol) format, so that Test::Harness will understand
+results. This is still in planning stages.
+</para>
+</section>
+
+</section>
+<section id="CodingGuidelines"><title>Coding guidelines</title>
+ <para>See <ulink url="http://www.gnu.org/prep/standards_toc.html">GNU
+ Coding standards</ulink> for general guidelines.</para>
+ <section><title>Comments</title>
+ <para>You should use /* */ for comments and not // as some compilers
+ do not handle the latter form.</para>
+ <para>If you have copied a routine from another source, make sure the licence
+ from your source allows this. Add a comment referencing the ACKNOWLEDGEMENTS
+ file, where you can put more detail about the source.</para>
+ <para>For contributed code, do not add any named credits in the source code
+ - contributors should be added into the THANKS.in file instead.
+ </para>
+ </section>
+
+ <section><title>CVS comments</title>
+ <para>When adding CVS comments at commit time, you can use the following prefixes:
+ <variablelist>
+ <varlistentry><term>- comment</term>
+ <listitem>
+ <para>for a comment that can be removed from the Changelog</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>* comment</term>
+ <listitem>
+ <para>for an important amendment to be included into a features list</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </para>
+ <para>If the change is due to a contribution, please quote the contributor's name
+ and, if applicable, add the SourceForge Tracker number. Don't forget to
+update the THANKS.in file.</para>
+ </section>
+
+ <section id="translations_developers"><title>Translations for developers</title>
+ <para>To make the job easier for translators, please follow these guidelines:</para>
+ <orderedlist>
+ <listitem><para>
+ Before creating new strings, check the po/nagios-plugins.pot file to
+ see if a similar string
+ already exists
+ </para></listitem>
+ <listitem><para>
+ For help texts, break into individual options so that these can be reused
+ between plugins
+ </para></listitem>
+ <listitem><para>Try to avoid linefeeds unless you are working on a block of text</para></listitem>
+ <listitem><para>Short help is not translated</para></listitem>
+ <listitem><para>Long help has options in English language, but text translated</para></listitem>
+ <listitem><para>"Copyright" kept in English</para></listitem>
+ <listitem><para>Copyright holder names kept in original text</para></listitem>
+ <listitem><para>Debugging output does not need to be translated</para></listitem>
+ </orderedlist>
+ </section>
+
+ <section><title>Translations for translators</title>
+ <para>To create an up to date list of translatable strings, run: tools/gen_locale.sh</para>
+ </section>
+
+</section>
+
+<section id="SubmittingChanges"><title>Submission of new plugins and patches</title>
+
+ <section id="Patches"><title>Patches</title>
+ <para>If you have a bug patch, please supply a unified or context diff against the
+ version you are using. For new features, please supply a diff against
+ the CVS HEAD version.</para>
+
+ <para>Patches should be submitted via
+ <ulink url="http://sourceforge.net/tracker/?group_id=29880&atid=397599">SourceForge's
+ tracker system for Nagiosplug patches</ulink>
+ and be announced to the nagiosplug-devel mailing list.</para>
+
+ <para>Submission of a patch implies that the submmitter acknowledges that they
+ are the author of the code (or have permission from the author to release the code)
+ and agree that the code can be released under the GPL. The copyright for the changes will
+ then revert to the Nagios Plugin Development Team - this is required so that any copyright
+ infringements can be investigated quickly without contacting a huge list of copyright holders.
+ Credit will always be given for any patches through a THANKS file in the distribution.</para>
+ </section>
+
+ <section id="Newplugins"><title>New plugins</title>
+
+ <para>If you would like others to use your plugins, please add it to
+ the official 3rd party plugin repository,
+ <ulink url="http://www.nagiosexchange.org">NagiosExchange</ulink>.
+ </para>
+
+ <para>We are not accepting requests for inclusion of plugins into
+ our distribution at the moment, but when we do, these are the minimum
+ requirements:
+ </para>
+
+ <orderedlist>
+ <listitem>
+ <para>Include copyright and license information in all files</para>
+ </listitem>
+ <listitem>
+ <para>The standard command options are supported (--help, --version,
+ --timeout, --warning, --critical)</para>
+ </listitem>
+ <listitem>
+ <para>It is determined to be not redundant (for instance, we would not
+ add a new version of check_disk just because someone had provide
+ a plugin that had perf checking - we would incorporate the features
+ into an exisiting plugin)</para>
+ </listitem>
+ <listitem>
+ <para>One of the developers has had the time to audit the code and declare
+ it ready for core</para>
+ </listitem>
+ <listitem>
+ <para>It should also follow code format guidelines, and use functions from
+utils (perl or c or sh) rather than using its own</para>
+ </listitem>
+ <listitem>
+ <para>Includes patches to configure.in if required (via the EXTRAS list if
+ it will only work on some platforms)</para>
+ </listitem>
+ <listitem>
+ <para>If possible, please submit a test harness. Documentation on sample
+ tests coming soon</para>
+ </listitem>
+ </orderedlist>
- <para>If possible please submit a test harness. Documentation on sample
- tests coming soon.</para>
+ </section>
</section>
</article>