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><DIV
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><A
NAME="AEN1"
></A
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="AEN3"
>Nagios plug-in development guidelines</A
></H1
><H3
CLASS="AUTHOR"
><A
NAME="AEN5"
></A
></H3
><DIV
CLASS="AFFILIATION"
><SPAN
CLASS="ORGNAME"
>Nagios Plugins Development Team<BR></SPAN
></DIV
><P
CLASS="COPYRIGHT"
>Copyright © 2000 - 2006 Nagios Plugins Development Team</P
><HR></DIV
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="#PREFACE"
>Preface</A
></DT
><DT
><A
HREF="#AEN23"
></A
></DT
><DD
><DL
><DT
>1. <A
HREF="#DEVREQUIREMENTS"
>Development platform requirements</A
></DT
><DT
>2. <A
HREF="#PLUGOUTPUT"
>Plugin Output for Nagios</A
></DT
><DD
><DL
><DT
>2.1. <A
HREF="#AEN35"
>Print only one line of text</A
></DT
><DT
>2.2. <A
HREF="#AEN41"
>Verbose output</A
></DT
><DT
>2.3. <A
HREF="#AEN74"
>Screen Output</A
></DT
><DT
>2.4. <A
HREF="#AEN78"
>Plugin Return Codes</A
></DT
><DT
>2.5. <A
HREF="#THRESHOLDFORMAT"
>Threshold and ranges</A
></DT
><DT
>2.6. <A
HREF="#AEN203"
>Performance data</A
></DT
><DT
>2.7. <A
HREF="#AEN242"
>Translations</A
></DT
></DL
></DD
><DT
>3. <A
HREF="#SYSCMDAUXFILES"
>System Commands and Auxiliary Files</A
></DT
><DD
><DL
><DT
>3.1. <A
HREF="#AEN248"
>Don't execute system commands without specifying their
full path</A
></DT
><DT
>3.2. <A
HREF="#AEN252"
>Use spopen() if external commands must be executed</A
></DT
><DT
>3.3. <A
HREF="#AEN256"
>Don't make temp files unless absolutely required</A
></DT
><DT
>3.4. <A
HREF="#AEN259"
>Don't be tricked into following symlinks</A
></DT
><DT
>3.5. <A
HREF="#AEN262"
>Validate all input</A
></DT
></DL
></DD
><DT
>4. <A
HREF="#PERLPLUGIN"
>Perl Plugins</A
></DT
><DT
>5. <A
HREF="#RUNTIME"
>Runtime Timeouts</A
></DT
><DD
><DL
><DT
>5.1. <A
HREF="#AEN296"
>Use DEFAULT_SOCKET_TIMEOUT</A
></DT
><DT
>5.2. <A
HREF="#AEN299"
>Add alarms to network plugins</A
></DT
></DL
></DD
><DT
>6. <A
HREF="#PLUGOPTIONS"
>Plugin Options</A
></DT
><DD
><DL
><DT
>6.1. <A
HREF="#AEN305"
>Option Processing</A
></DT
><DT
>6.2. <A
HREF="#AEN320"
>Plugins with more than one type of threshold, or with
threshold ranges</A
></DT
></DL
></DD
><DT
>7. <A
HREF="#TESTCASES"
>Test cases</A
></DT
><DD
><DL
><DT
>7.1. <A
HREF="#AEN343"
>Test cases for plugins</A
></DT
><DT
>7.2. <A
HREF="#AEN350"
>Testing the C library functions</A
></DT
></DL
></DD
><DT
>8. <A
HREF="#CODINGGUIDELINES"
>Coding guidelines</A
></DT
><DD
><DL
><DT
>8.1. <A
HREF="#AEN361"
>C coding</A
></DT
><DT
>8.2. <A
HREF="#AEN366"
>Crediting sources</A
></DT
><DT
>8.3. <A
HREF="#AEN370"
>CVS comments</A
></DT
><DT
>8.4. <A
HREF="#TRANSLATIONSDEVELOPERS"
>Translations for developers</A
></DT
><DT
>8.5. <A
HREF="#AEN395"
>Translations for translators</A
></DT
></DL
></DD
><DT
>9. <A
HREF="#SUBMITTINGCHANGES"
>Submission of new plugins and patches</A
></DT
><DD
><DL
><DT
>9.1. <A
HREF="#PATCHES"
>Patches</A
></DT
><DT
>9.2. <A
HREF="#CONTRIBUTEDPLUGINS"
>Contributed plugins</A
></DT
><DT
>9.3. <A
HREF="#NEWPLUGINS"
>New plugins</A
></DT
></DL
></DD
></DL
></DD
></DL
></DIV
><DIV
CLASS="LOT"
><DL
CLASS="LOT"
><DT
><B
>List of Tables</B
></DT
><DT
>1. <A
HREF="#VERBOSELEVELS"
>Verbose output levels</A
></DT
><DT
>2. <A
HREF="#RETURNCODES"
>Plugin Return Codes</A
></DT
><DT
>3. <A
HREF="#EXAMPLERANGES"
>Example ranges</A
></DT
><DT
>4. <A
HREF="#COMMANDLINEEXAMPLES"
>Command line examples</A
></DT
></DL
></DIV
><DIV
CLASS="PREFACE"
><HR><H1
><A
NAME="PREFACE"
></A
>Preface</H1
><P
>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.</P
><P
>Nagios Plug-in Development Guidelines Copyright (C) 2000-2006
(Nagios Plugins Team)</P
><P
>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.</P
><P
>The plugins themselves are copyrighted by their respective
authors.</P
></DIV
><DIV
CLASS="ARTICLE"
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>1. <A
HREF="#DEVREQUIREMENTS"
>Development platform requirements</A
></DT
><DT
>2. <A
HREF="#PLUGOUTPUT"
>Plugin Output for Nagios</A
></DT
><DD
><DL
><DT
>2.1. <A
HREF="#AEN35"
>Print only one line of text</A
></DT
><DT
>2.2. <A
HREF="#AEN41"
>Verbose output</A
></DT
><DT
>2.3. <A
HREF="#AEN74"
>Screen Output</A
></DT
><DT
>2.4. <A
HREF="#AEN78"
>Plugin Return Codes</A
></DT
><DT
>2.5. <A
HREF="#THRESHOLDFORMAT"
>Threshold and ranges</A
></DT
><DT
>2.6. <A
HREF="#AEN203"
>Performance data</A
></DT
><DT
>2.7. <A
HREF="#AEN242"
>Translations</A
></DT
></DL
></DD
><DT
>3. <A
HREF="#SYSCMDAUXFILES"
>System Commands and Auxiliary Files</A
></DT
><DD
><DL
><DT
>3.1. <A
HREF="#AEN248"
>Don't execute system commands without specifying their
full path</A
></DT
><DT
>3.2. <A
HREF="#AEN252"
>Use spopen() if external commands must be executed</A
></DT
><DT
>3.3. <A
HREF="#AEN256"
>Don't make temp files unless absolutely required</A
></DT
><DT
>3.4. <A
HREF="#AEN259"
>Don't be tricked into following symlinks</A
></DT
><DT
>3.5. <A
HREF="#AEN262"
>Validate all input</A
></DT
></DL
></DD
><DT
>4. <A
HREF="#PERLPLUGIN"
>Perl Plugins</A
></DT
><DT
>5. <A
HREF="#RUNTIME"
>Runtime Timeouts</A
></DT
><DD
><DL
><DT
>5.1. <A
HREF="#AEN296"
>Use DEFAULT_SOCKET_TIMEOUT</A
></DT
><DT
>5.2. <A
HREF="#AEN299"
>Add alarms to network plugins</A
></DT
></DL
></DD
><DT
>6. <A
HREF="#PLUGOPTIONS"
>Plugin Options</A
></DT
><DD
><DL
><DT
>6.1. <A
HREF="#AEN305"
>Option Processing</A
></DT
><DT
>6.2. <A
HREF="#AEN320"
>Plugins with more than one type of threshold, or with
threshold ranges</A
></DT
></DL
></DD
><DT
>7. <A
HREF="#TESTCASES"
>Test cases</A
></DT
><DD
><DL
><DT
>7.1. <A
HREF="#AEN343"
>Test cases for plugins</A
></DT
><DT
>7.2. <A
HREF="#AEN350"
>Testing the C library functions</A
></DT
></DL
></DD
><DT
>8. <A
HREF="#CODINGGUIDELINES"
>Coding guidelines</A
></DT
><DD
><DL
><DT
>8.1. <A
HREF="#AEN361"
>C coding</A
></DT
><DT
>8.2. <A
HREF="#AEN366"
>Crediting sources</A
></DT
><DT
>8.3. <A
HREF="#AEN370"
>CVS comments</A
></DT
><DT
>8.4. <A
HREF="#TRANSLATIONSDEVELOPERS"
>Translations for developers</A
></DT
><DT
>8.5. <A
HREF="#AEN395"
>Translations for translators</A
></DT
></DL
></DD
><DT
>9. <A
HREF="#SUBMITTINGCHANGES"
>Submission of new plugins and patches</A
></DT
><DD
><DL
><DT
>9.1. <A
HREF="#PATCHES"
>Patches</A
></DT
><DT
>9.2. <A
HREF="#CONTRIBUTEDPLUGINS"
>Contributed plugins</A
></DT
><DT
>9.3. <A
HREF="#NEWPLUGINS"
>New plugins</A
></DT
></DL
></DD
></DL
></DIV
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="DEVREQUIREMENTS"
>1. Development platform requirements</A
></H2
><P
> 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
are very basic, developing from the git repository requires additional software to be installed. These are the
minimum levels of software required:
<P
CLASS="LITERALLAYOUT"
> gnu make 3.79<br>
automake 1.9.2<br>
autoconf 2.59<br>
gnu m4 1.4.2<br>
gnu libtool 1.5<br>
</P
>
To compile from git, after you have checked out the code run:
<P
CLASS="LITERALLAYOUT"
> tools/setup<br>
./configure<br>
make<br>
make install<br>
</P
>
</P
><P
>Note: gettext is no longer a developer platform requirement. A lot of the files in lib/ and m4/
are synced with the coreutils project and we use the same levels of gettext that they
distribute.
</P
><P
>Note: GNU libtool, which must be at version 1.5.22 or above, has its files included in the git repository, so is not
a development platform requirement.
</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="PLUGOUTPUT"
>2. Plugin Output for Nagios</A
></H2
><P
>You should always print something to STDOUT that tells if the
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.</P
><P
>As Nagios does not capture stderr output, you should only output to
STDOUT and not print to STDERR.</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN35"
>2.1. Print only one line of text</A
></H3
><P
>Nagios will only grab the first line of text from STDOUT
when it notifies contacts about potential problems. If you print
multiple lines, you're out of luck (though this will be a feature of
Nagios 3). Remember, keep your output short and to the point.</P
><P
>Output should be in the format:</P
><P
CLASS="LITERALLAYOUT"
> SERVICE STATUS: Information text<br>
</P
><P
>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.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN41"
>2.2. Verbose output</A
></H3
><P
>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:</P
><DIV
CLASS="TABLE"
><A
NAME="VERBOSELEVELS"
></A
><P
><B
>Table 1. Verbose output levels</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
><P
>Verbosity level</P
></TH
><TH
><P
>Type of output</P
></TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="CENTER"
><P
>0</P
></TD
><TD
><P
>Single line, minimal output. Summary</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>1</P
></TD
><TD
><P
>Single line, additional information (eg list processes that fail)</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>2</P
></TD
><TD
><P
>Multi line, configuration debug output (eg ps command used)</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>3</P
></TD
><TD
><P
>Lots of detail for plugin problem diagnosis</P
></TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN74"
>2.3. Screen Output</A
></H3
><P
>The plug-in should print the diagnostic and just the
usage part of the help message. A well written plugin would
then have --help as a way to get the verbose help.</P
><P
>Code and output should try to respect the 80x25 size of a
crt (remember when fixing stuff in the server room!)</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN78"
>2.4. Plugin Return Codes</A
></H3
><P
>The return codes below are based on the POSIX spec of returning
a positive value. Netsaint prior to v0.0.7 supported non-POSIX
compliant return code of "-1" for unknown. Nagios supports POSIX return
codes by default.</P
><P
>Note: Some plugins will on occasion print on STDOUT that an error
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 UNKNOWN
return code.</P
><DIV
CLASS="TABLE"
><A
NAME="RETURNCODES"
></A
><P
><B
>Table 2. Plugin Return Codes</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
><P
>Numeric Value</P
></TH
><TH
><P
>Service Status</P
></TH
><TH
><P
>Status Description</P
></TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="CENTER"
><P
>0</P
></TD
><TD
VALIGN="MIDDLE"
><P
>OK</P
></TD
><TD
><P
>The plugin was able to check the service and it
appeared to be functioning properly</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>1</P
></TD
><TD
VALIGN="MIDDLE"
><P
>Warning</P
></TD
><TD
><P
>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</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>2</P
></TD
><TD
VALIGN="MIDDLE"
><P
>Critical</P
></TD
><TD
><P
>The plugin detected that either the service was not
running or it was above some "critical" threshold</P
></TD
></TR
><TR
><TD
ALIGN="CENTER"
><P
>3</P
></TD
><TD
VALIGN="MIDDLE"
><P
>Unknown</P
></TD
><TD
><P
>Invalid command line arguments were supplied to the
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.
</P
></TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="THRESHOLDFORMAT"
>2.5. Threshold and ranges</A
></H3
><P
>A range is defined as a start and end point (inclusive) on a numeric scale (possibly
negative or positive infinity).
</P
><P
>A threshold is a range with an alert level (either warning or critical). Use the
set_thresholds(thresholds *, char *, char *) function to set the thresholds.
</P
><P
>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. Use the get_status(double, thresholds *) function to
compare the value against the thresholds.</P
><P
>This is the generalised format for ranges:</P
><P
CLASS="LITERALLAYOUT"
> [@]start:end<br>
</P
><P
>Notes:</P
><P
></P
><OL
TYPE="1"
><LI
><P
>start ≤ end</P
></LI
><LI
><P
>start and ":" is not required if start=0</P
></LI
><LI
><P
>if range is of format "start:" and end is not specified,
assume end is infinity</P
></LI
><LI
><P
>to specify negative infinity, use "~"</P
></LI
><LI
><P
>alert is raised if metric is outside start and end range
(inclusive of endpoints)</P
></LI
><LI
><P
>if range starts with "@", then alert if inside this range
(inclusive of endpoints)</P
></LI
></OL
><P
>Note: Not all plugins are coded to expect ranges in this format yet.
There will be some work in providing multiple metrics.</P
><DIV
CLASS="TABLE"
><A
NAME="EXAMPLERANGES"
></A
><P
><B
>Table 3. Example ranges</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
><P
>Range definition</P
></TH
><TH
><P
>Generate an alert if x...</P
></TH
></TR
></THEAD
><TBODY
><TR
><TD
>10</TD
><TD
>< 0 or > 10, (outside the range of {0 .. 10})</TD
></TR
><TR
><TD
>10:</TD
><TD
>< 10, (outside {10 .. ∞})</TD
></TR
><TR
><TD
>~:10</TD
><TD
>> 10, (outside the range of {-∞ .. 10})</TD
></TR
><TR
><TD
>10:20</TD
><TD
>< 10 or > 20, (outside the range of {10 .. 20})</TD
></TR
><TR
><TD
>@10:20</TD
><TD
>≥ 10 and ≤ 20, (inside the range of {10 .. 20})</TD
></TR
><TR
><TD
>10</TD
><TD
>< 0 or > 10, (outside the range of {0 .. 10})</TD
></TR
></TBODY
></TABLE
></DIV
><DIV
CLASS="TABLE"
><A
NAME="COMMANDLINEEXAMPLES"
></A
><P
><B
>Table 4. Command line examples</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
><P
>Command line</P
></TH
><TH
><P
>Meaning</P
></TH
></TR
></THEAD
><TBODY
><TR
><TD
>check_stuff -w10 -c20</TD
><TD
>Critical if "stuff" is over 20, else warn if over 10 (will be critical if "stuff" is less than 0)</TD
></TR
><TR
><TD
>check_stuff -w~:10 -c~:20</TD
><TD
>Same as above. Negative "stuff" is OK</TD
></TR
><TR
><TD
>check_stuff -w10: -c20</TD
><TD
>Critical if "stuff" is over 20, else warn if "stuff" is below 10 (will be critical if "stuff" is less than 0)</TD
></TR
><TR
><TD
>check_stuff -c1:</TD
><TD
>Critical if "stuff" is less than 1</TD
></TR
><TR
><TD
>check_stuff -w~:0 -c10</TD
><TD
>Critical if "stuff" is above 10; Warn if "stuff" is above zero</TD
></TR
><TR
><TD
>check_stuff -c5:6</TD
><TD
>The only noncritical range is 5:6</TD
></TR
><TR
><TD
>check_stuff -c10:20</TD
><TD
>Critical if "stuff" is 10 to 20</TD
></TR
></TBODY
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN203"
>2.6. Performance data</A
></H3
><P
>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:</P
><P
CLASS="LITERALLAYOUT"
> 'label'=value[UOM];[warn];[crit];[min];[max]<br>
</P
><P
>Notes:</P
><P
></P
><OL
TYPE="1"
><LI
><P
>space separated list of label/value pairs</P
></LI
><LI
><P
>label can contain any characters</P
></LI
><LI
><P
>the single quotes for the label are optional. Required if
spaces, = or ' are in the label</P
></LI
><LI
><P
>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</P
></LI
><LI
><P
>to specify a quote character, use two single quotes</P
></LI
><LI
><P
>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</P
></LI
><LI
><P
>min and max are not required if UOM=%</P
></LI
><LI
><P
>value, min and max in class [-0-9.]. Must all be the
same UOM</P
></LI
><LI
><P
>warn and crit are in the range format (see
<A
HREF="#THRESHOLDFORMAT"
>Section 2.5</A
>). Must be the same UOM</P
></LI
><LI
><P
>UOM (unit of measurement) is one of:</P
><P
></P
><OL
TYPE="a"
><LI
><P
>no unit specified - assume a number (int or float)
of things (eg, users, processes, load averages)</P
></LI
><LI
><P
>s - seconds (also us, ms)</P
></LI
><LI
><P
>% - percentage</P
></LI
><LI
><P
>B - bytes (also KB, MB, TB)</P
></LI
><LI
><P
>c - a continous counter (such as bytes
transmitted on an interface)</P
></LI
></OL
></LI
></OL
><P
>It is up to third party programs to convert the Nagios plugins
performance data into graphs.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN242"
>2.7. Translations</A
></H3
><P
>If possible, use translation tools for all output to respect the user's language
settings. See <A
HREF="#TRANSLATIONSDEVELOPERS"
>Section 8.4</A
> for guidelines
for the core plugins.
</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SYSCMDAUXFILES"
>3. System Commands and Auxiliary Files</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="AEN248"
>3.1. Don't execute system commands without specifying their
full path</A
></H3
><P
>Don't use exec(), popen(), etc. to execute external
commands without explicity using the full path of the external
program.</P
><P
>Doing otherwise makes the plugin vulnerable to hijacking
by a trojan horse earlier in the search path. See the main
plugin distribution for examples on how this is done.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN252"
>3.2. Use spopen() if external commands must be executed</A
></H3
><P
>If you have to execute external commands from within your
plugin and you're writing it in C, use the spopen() function
that Karl DeBisschop has written.</P
><P
>The code for spopen() and spclose() is included with the
core plugin distribution.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN256"
>3.3. Don't make temp files unless absolutely required</A
></H3
><P
>If temp files are needed, make sure that the plugin will
fail cleanly if the file can't be written (e.g., too few file
handles, out of disk space, incorrect permissions, etc.) and
delete the temp file when processing is complete.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN259"
>3.4. Don't be tricked into following symlinks</A
></H3
><P
>If your plugin opens any files, take steps to ensure that
you are not following a symlink to another location on the
system.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN262"
>3.5. Validate all input</A
></H3
><P
>use routines in utils.c or utils.pm and write more as needed</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="PERLPLUGIN"
>4. Perl Plugins</A
></H2
><P
>Perl plugins are coded a little more defensively than other
plugins because of embedded Perl. When configured as such, embedded
Perl Nagios (ePN) requires stricter use of the some of Perl's features.
This section outlines some of the steps needed to use ePN
effectively.</P
><P
></P
><OL
TYPE="1"
><LI
><P
> Do not use BEGIN and END blocks since they will be called
only once (when Nagios starts and shuts down) with Embedded Perl (ePN). In
particular, do not use BEGIN blocks to initialize variables.</P
></LI
><LI
><P
>To use utils.pm, you need to provide a full path to the
module in order for it to work.</P
><P
CLASS="LITERALLAYOUT"
> e.g.<br>
use lib "/usr/local/nagios/libexec";<br>
use utils qw(...);<br>
</P
></LI
><LI
><P
>Perl scripts should be called with "-w"</P
></LI
><LI
><P
>All Perl plugins must compile cleanly under "use strict" - i.e. at
least explicitly package names as in "$main::x" or predeclare every
variable. </P
><P
>Explicitly initialize each variable in use. Otherwise with
caching enabled, the plugin will not be recompiled each time, and
therefore Perl will not reinitialize all the variables. All old
variable values will still be in effect.</P
></LI
><LI
><P
>Do not use >DATA< handles (these simply do not compile under ePN).</P
></LI
><LI
><P
>Do not use global variables in named subroutines. This is bad practise anyway, but with ePN the
compiler will report an error "<global_var> will not stay shared ..". Values used by
subroutines should be passed in the argument list.</P
></LI
><LI
><P
>If writing to a file (perhaps recording
performance data) explicitly close close it. The plugin never
calls <SPAN
CLASS="strong"
><B
CLASS="EMPHASIS"
>exit</B
></SPAN
>; that is caught by
p1.pl, so output streams are never closed.</P
></LI
><LI
><P
>As in <A
HREF="#RUNTIME"
>Section 5</A
> all plugins need
to monitor their runtime, specially if they are using network
resources. Use of the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>alarm</I
></SPAN
> is recommended
noting that some Perl modules (eg LWP) manage timers, so that an alarm
set by a plugin using such a module is overwritten by the module.
(workarounds are cunning (TM) or using the module timer)
Plugins may import a default time out ($TIMEOUT) from utils.pm.
</P
></LI
><LI
><P
>Perl plugins should import %ERRORS from utils.pm
and then "exit $ERRORS{'OK'}" rather than "exit 0"
</P
></LI
></OL
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="RUNTIME"
>5. Runtime Timeouts</A
></H2
><P
>Plugins have a very limited runtime - typically 10 sec.
As a result, it is very important for plugins to maintain internal
code to exit if runtime exceeds a threshold. </P
><P
>All plugins should timeout gracefully, not just networking
plugins. For instance, df may lock if you have automounted
drives and your network fails - but on first glance, who'd think
df could lock up like that. Plus, it should just be more error
resistant to be able to time out rather than consume
resources.</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN296"
>5.1. Use DEFAULT_SOCKET_TIMEOUT</A
></H3
><P
>All network plugins should use DEFAULT_SOCKET_TIMEOUT to timeout</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN299"
>5.2. Add alarms to network plugins</A
></H3
><P
>If you write a plugin which communicates with another
networked host, you should make sure to set an alarm() in your
code that prevents the plugin from hanging due to abnormal
socket closures, etc. Nagios takes steps to protect itself
against unruly plugins that timeout, but any plugins you create
should be well behaved on their own.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="PLUGOPTIONS"
>6. Plugin Options</A
></H2
><P
>A well written plugin should have --help as a way to get
verbose help. Code and output should try to respect the 80x25 size of a
crt (remember when fixing stuff in the server room!)</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN305"
>6.1. Option Processing</A
></H3
><P
>For plugins written in C, we recommend the C standard
getopt library for short options. Getopt_long is always available.
</P
><P
>For plugins written in Perl, we recommend Getopt::Long module.</P
><P
>Positional arguments are strongly discouraged.</P
><P
>There are a few reserved options that should not be used
for other purposes:</P
><P
CLASS="LITERALLAYOUT"
> -V version (--version)<br>
-h help (--help)<br>
-t timeout (--timeout)<br>
-w warning threshold (--warning)<br>
-c critical threshold (--critical)<br>
-H hostname (--hostname)<br>
-v verbose (--verbose)<br>
</P
><P
>In addition to the reserved options above, some other standard options are:</P
><P
CLASS="LITERALLAYOUT"
> -C SNMP community (--community)<br>
-a authentication password (--authentication)<br>
-l login name (--logname)<br>
-p port or password (--port or --passwd/--password)monitors operational<br>
-u url or username (--url or --username)<br>
</P
><P
>Look at check_pgsql and check_procs to see how I currently
think this can work. Standard options are:</P
><P
>The option -V or --version should be present in all
plugins. For C plugins it should result in a call to print_revision, a
function in utils.c which takes two character arguments, the
command name and the plugin revision.</P
><P
>The -? option, or any other unparsable set of options,
should print out a short usage statement. Character width should
be 80 and less and no more that 23 lines should be printed (it
should display cleanly on a dumb terminal in a server
room).</P
><P
>The option -h or --help should be present in all plugins.
In C plugins, it should result in a call to print_help (or
equivalent). The function print_help should call print_revision,
then print_usage, then should provide detailed
help. Help text should fit on an 80-character width display, but
may run as many lines as needed.</P
><P
>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 <A
HREF="#VERBOSELEVELS"
>Table 1</A
>.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN320"
>6.2. Plugins with more than one type of threshold, or with
threshold ranges</A
></H3
><P
>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 alternatives are:</P
><P
></P
><OL
TYPE="1"
><LI
><P
>long options like -critical-time (or -ct and -cv, I
suppose).</P
></LI
><LI
><P
>repeated options like `check_load -w 10 -w 6 -w 4 -c
16 -c 10 -c 10`</P
></LI
><LI
><P
>for brevity, the above can be expressed as `check_load
-w 10,6,4 -c 16,10,10`</P
></LI
><LI
><P
>ranges are expressed with colons as in `check_procs -C
httpd -w 1:20 -c 1:30` which will warn above 20 instances,
and critical at 0 and above 30</P
></LI
><LI
><P
>lists are expressed with commas, so Jacob's check_nmap
uses constructs like '-p 1000,1010,1050:1060,2000'</P
></LI
><LI
><P
>If possible when writing lists, use tokens to make the
list easy to remember and non-order dependent - so
check_disk uses '-c 10000,10%' so that it is clear which is
the precentage and which is the KB values (note that due to
my own lack of foresight, that used to be '-c 10000:10%' but
such constructs should all be changed for consistency,
though providing reverse compatibility is fairly
easy).</P
></LI
></OL
><P
>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.
</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="TESTCASES"
>7. Test cases</A
></H2
><P
>Tests are the best way of knowing if the plugins work as expected. Please
create and update test cases where possible.</P
><P
>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.</P
><P
>See the <A
HREF="http://tinderbox.altinity.org"
TARGET="_top"
>Nagios Plugins Tinderbox server</A
>
for the daily test results.</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN343"
>7.1. Test cases for plugins</A
></H3
><P
>These use perl's Test::More. To do a one time test, run "cd plugins && perl t/check_disk.t".</P
><P
>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!)</P
><P
>If you want a summary test, run: "cd plugins && prove t/check_disk.t".
This runs the test in a summary format.</P
><P
>For a good and amusing tutorial on using Test::More, see this
<A
HREF="http://search.cpan.org/~mschwern/Test-Simple-0.62/lib/Test/Tutorial.pod"
TARGET="_top"
>link</A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN350"
>7.2. Testing the C library functions</A
></H3
><P
>We use <A
HREF="http://jc.ngo.org.uk/trac-bin/trac.cgi/wiki/LibTap"
TARGET="_top"
>the libtap library</A
>, which gives
perl's TAP
(Test Anything Protocol) output. This is used by the FreeBSD team for their regression testing.</P
><P
>To run tests using the libtap library, download the latest tar ball and extract.
There is a problem with tap-1.01 where
<A
HREF="http://jc.ngo.org.uk/trac-bin/trac.cgi/ticket/25"
TARGET="_top"
>pthread support doesn't appear to work</A
>
properly on non-FreeBSD systems. Install with 'CPPFLAGS="-UHAVE_LIBPTHREAD" ./configure && make && make check && make install'. </P
><P
>When you run Nagios Plugins' configure, it will look for the tap library and will automatically
setup the tests. Run "make test" to run all the tests.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="CODINGGUIDELINES"
>8. Coding guidelines</A
></H2
><P
>See <A
HREF="http://www.gnu.org/prep/standards_toc.html"
TARGET="_top"
>GNU
Coding standards</A
> for general guidelines.</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN361"
>8.1. C coding</A
></H3
><P
>Variables should be declared at the beginning of code blocks and
not inline because of portability with older compilers.</P
><P
>You should use /* */ for comments and not // as some compilers
do not handle the latter form.</P
><P
>You should also avoid using the type "bool" and its values
"true" and "false". Instead use the "int" type and the plugins' own
"TRUE"/"FALSE" values to keep the code uniformly.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN366"
>8.2. Crediting sources</A
></H3
><P
>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.</P
><P
>For contributed code, do not add any named credits in the source code
- contributors should be added into the THANKS.in file instead.
</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN370"
>8.3. CVS comments</A
></H3
><P
>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.</P
><P
>If you have a change that is useful for noting in the next release, please
update the NEWS file.</P
><P
>All commit comments are written to a ChangeLog at release time.
</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="TRANSLATIONSDEVELOPERS"
>8.4. Translations for developers</A
></H3
><P
>To make the job easier for translators, please follow these guidelines:</P
><P
></P
><OL
TYPE="1"
><LI
><P
> Before creating new strings, check the po/nagios-plugins.pot file to
see if a similar string
already exists
</P
></LI
><LI
><P
> For help texts, break into individual options so that these can be reused
between plugins
</P
></LI
><LI
><P
>Try to avoid linefeeds unless you are working on a block of text</P
></LI
><LI
><P
>Short help is not translated</P
></LI
><LI
><P
>Long help has options in English language, but text translated</P
></LI
><LI
><P
>"Copyright" kept in English</P
></LI
><LI
><P
>Copyright holder names kept in original text</P
></LI
><LI
><P
>Debugging output does not need to be translated</P
></LI
></OL
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN395"
>8.5. Translations for translators</A
></H3
><P
>To create an up to date list of translatable strings, run: tools/gen_locale.sh</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SUBMITTINGCHANGES"
>9. Submission of new plugins and patches</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PATCHES"
>9.1. Patches</A
></H3
><P
>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 git HEAD version.</P
><P
>Patches should be submitted via
<A
HREF="http://sourceforge.net/tracker/?group_id=29880&atid=397599"
TARGET="_top"
>SourceForge's
tracker system for Nagiosplug patches</A
>
and be announced to the nagiosplug-devel mailing list.</P
><P
>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.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="CONTRIBUTEDPLUGINS"
>9.2. Contributed plugins</A
></H3
><P
>Plugins that have been contributed to the project and
distributed with the Nagios Plugin files are held in the contrib/ directory and are not installed
by default. These plugins are not officially supported by the team.
The current policy is that these plugins should be owned and maintained by the original
contributor, preferably hosted on <A
HREF="http://www.nagiosexchange.org"
TARGET="_top"
>NagiosExchange</A
>.
</P
><P
>If patches or bugs are raised to an contributed plugin, we will start communications with the
original contributor, but seek to remove the plugin from our distribution.
</P
><P
>The aim is to distribute only code that the Nagios Plugin team are responsible for.
</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="NEWPLUGINS"
>9.3. New plugins</A
></H3
><P
>If you would like others to use your plugins, please add it to
the official 3rd party plugin repository,
<A
HREF="http://www.nagiosexchange.org"
TARGET="_top"
>NagiosExchange</A
>.
</P
><P
>We are not accepting requests for inclusion of plugins into
our distribution at the moment, but when we do, these are the minimum
requirements:
</P
><P
></P
><OL
TYPE="1"
><LI
><P
>Include copyright and license information in all files. Copyright must be solely
granted to the Nagios Plugin Development Team</P
></LI
><LI
><P
>The standard command options are supported (--help, --version,
--timeout, --warning, --critical)</P
></LI
><LI
><P
>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)</P
></LI
><LI
><P
>One of the developers has had the time to audit the code and declare
it ready for core</P
></LI
><LI
><P
>It should also follow code format guidelines, and use functions from
utils (perl or c or sh) rather than using its own</P
></LI
><LI
><P
>Includes patches to configure.in if required (via the EXTRAS list if
it will only work on some platforms)</P
></LI
><LI
><P
>If possible, please submit a test harness. Documentation on sample
tests coming soon</P
></LI
></OL
></DIV
></DIV
></DIV
></DIV
></BODY
></HTML
>