diff options
| author |  Ton Voon <tonvoon@users.sourceforge.net>
| 2003-05-13 22:03:48 +0000 |
|---|---|---|
| committer | Ton Voon <tonvoon@users.sourceforge.net>
| 2003-05-13 22:03:48 +0000 |
| commit | 54921a5e45644a4b94bc0550e76b30a0049474b8 (patch) | |
| tree | 2293af39659f516ad5b17f72f440cae219b43447 /doc/developer-guidelines.html | |
| parent | 110510283a83a0de913ad20b914415bb1ab77c46 (diff) | |
| download | monitoring-plugins-54921a5e45644a4b94bc0550e76b30a0049474b8.tar.gz | |
The developer-guidelines.html file is now generated from the sgml file
by docbook2html at tools/setup time
git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@506 f882894a-f735-0410-b71e-b25c423dba1c
Diffstat (limited to 'doc/developer-guidelines.html')
| -rw-r--r-- | doc/developer-guidelines.html | 931 |
1 files changed, 0 insertions, 931 deletions
diff --git a/doc/developer-guidelines.html b/doc/developer-guidelines.html deleted file mode 100644 index efac605f..00000000 --- a/doc/developer-guidelines.html +++ /dev/null @@ -1,931 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> -<HTML -><HEAD -><TITLE ->Nagios plug-in development guidelines</TITLE -><META -NAME="GENERATOR" -CONTENT="Modular DocBook HTML Stylesheet Version 1.64 -"></HEAD -><BODY -CLASS="BOOK" -BGCOLOR="#FFFFFF" -TEXT="#000000" -LINK="#0000FF" -VLINK="#840084" -ALINK="#0000FF" -><DIV -CLASS="BOOK" -><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" ->Karl DeBisschop</A -></H3 -><DIV -CLASS="AFFILIATION" -><DIV -CLASS="ADDRESS" -><P -CLASS="ADDRESS" ->karl@debisschop.net</P -></DIV -></DIV -><H3 -CLASS="AUTHOR" -><A -NAME="AEN11" ->Ethan Galstad</A -></H3 -><DIV -CLASS="AFFILIATION" -><DIV -CLASS="ADDRESS" -><P -CLASS="ADDRESS" ->netsaint@linuxbox.com</P -></DIV -></DIV -><H3 -CLASS="AUTHOR" -><A -NAME="AEN21" ->Hugo Gayosso</A -></H3 -><DIV -CLASS="AFFILIATION" -><DIV -CLASS="ADDRESS" -><P -CLASS="ADDRESS" ->hgayosso@gnu.org</P -></DIV -></DIV -><H3 -CLASS="AUTHOR" -><A -NAME="AEN27" ->Subhendu Ghosh</A -></H3 -><DIV -CLASS="AFFILIATION" -><DIV -CLASS="ADDRESS" -><P -CLASS="ADDRESS" ->sghosh@sourceforge.net</P -></DIV -></DIV -><H3 -CLASS="AUTHOR" -><A -NAME="AEN33" ->Stanley Hopcroft</A -></H3 -><DIV -CLASS="AFFILIATION" -><DIV -CLASS="ADDRESS" -><P -CLASS="ADDRESS" ->stanleyhopcroft@sourceforge.net</P -></DIV -></DIV -><P -CLASS="COPYRIGHT" ->Copyright © 2000 2001 2002 by Karl DeBisschop, Ethan Galstad, - Hugo Gayosso, Stanley Hopcroft, Subhendu Ghosh</P -><HR></DIV -><DIV -CLASS="TOC" -><DL -><DT -><B ->Table of Contents</B -></DT -><DT -><A -HREF="#PREFACE" ->About the guidelines</A -></DT -><DD -><DL -><DT -><A -HREF="#AEN51" ->Copyright</A -></DT -></DL -></DD -><DT -><A -HREF="#AEN56" -></A -></DT -><DD -><DL -><DT -><A -HREF="#PLUGOUTPUT" ->Plugin Output for Nagios</A -></DT -><DD -><DL -><DT -><A -HREF="#AEN60" ->Print only one line of text</A -></DT -><DT -><A -HREF="#AEN63" ->Screen Output</A -></DT -><DT -><A -HREF="#AEN67" ->Return the proper status code</A -></DT -><DT -><A -HREF="#AEN71" ->Plugin Return Codes</A -></DT -></DL -></DD -><DT -><A -HREF="#SYSCMDAUXFILES" ->System Commands and Auxiliary Files</A -></DT -><DD -><DL -><DT -><A -HREF="#AEN117" ->Don't execute system commands without specifying their - full path</A -></DT -><DT -><A -HREF="#AEN121" ->Use spopen() if external commands must be executed</A -></DT -><DT -><A -HREF="#AEN125" ->Don't make temp files unless absolutely required</A -></DT -><DT -><A -HREF="#AEN128" ->Don't be tricked into following symlinks</A -></DT -><DT -><A -HREF="#AEN131" ->Validate all input</A -></DT -></DL -></DD -><DT -><A -HREF="#PERLPLUGIN" ->Perl Plugins</A -></DT -><DT -><A -HREF="#RUNTIME" ->Runtime Timeouts</A -></DT -><DD -><DL -><DT -><A -HREF="#AEN165" ->Use DEFAULT_SOCKET_TIMEOUT</A -></DT -><DT -><A -HREF="#AEN168" ->Add alarms to network plugins</A -></DT -></DL -></DD -><DT -><A -HREF="#PLUGOPTIONS" ->Plugin Options</A -></DT -><DD -><DL -><DT -><A -HREF="#AEN174" ->Option Processing</A -></DT -><DT -><A -HREF="#AEN187" ->Plugins with more than one type of threshold, or with - threshold ranges</A -></DT -></DL -></DD -><DT -><A -HREF="#SUBMITTINGCHANGES" ->New submissions and patches</A -></DT -></DL -></DD -></DL -></DIV -><DIV -CLASS="PREFACE" -><HR><H1 -><A -NAME="PREFACE" ->About the guidelines</A -></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 -><DIV -CLASS="SECTION" -><HR><H1 -CLASS="SECTION" -><A -NAME="AEN51" ->Copyright</A -></H1 -><P ->Nagios Plug-in Development Guidelines Copyright (C) 2000 2001 - 2002 - Karl DeBisschop, Ethan Galstad, Hugo Gayosso, Stanley Hopcroft, - Subhendu Ghosh</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 -><DIV -CLASS="ARTICLE" -><DIV -CLASS="TOC" -><DL -><DT -><B ->Table of Contents</B -></DT -><DT -><A -HREF="#PLUGOUTPUT" ->Plugin Output for Nagios</A -></DT -><DT -><A -HREF="#SYSCMDAUXFILES" ->System Commands and Auxiliary Files</A -></DT -><DT -><A -HREF="#PERLPLUGIN" ->Perl Plugins</A -></DT -><DT -><A -HREF="#RUNTIME" ->Runtime Timeouts</A -></DT -><DT -><A -HREF="#PLUGOPTIONS" ->Plugin Options</A -></DT -><DT -><A -HREF="#SUBMITTINGCHANGES" ->New submissions and patches</A -></DT -></DL -></DIV -><DIV -CLASS="SECTION" -><H1 -CLASS="SECTION" -><A -NAME="PLUGOUTPUT" ->Plugin Output for Nagios</A -></H1 -><P ->You should always print something to STDOUT that tells if the - service is working or why its 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 -><DIV -CLASS="SECTION" -><HR><H2 -CLASS="SECTION" -><A -NAME="AEN60" ->Print only one line of text</A -></H2 -><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. Remember, keep it short and - to the point.</P -></DIV -><DIV -CLASS="SECTION" -><HR><H2 -CLASS="SECTION" -><A -NAME="AEN63" ->Screen Output</A -></H2 -><P ->The plug-in should print the diagnostic and just the - synopsis 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><H2 -CLASS="SECTION" -><A -NAME="AEN67" ->Return the proper status code</A -></H2 -><P ->See <A -HREF="#RETURNCODES" ->Table 1 in the section called <I ->Plugin Return Codes</I -></A -> 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.</P -></DIV -><DIV -CLASS="SECTION" -><HR><H2 -CLASS="SECTION" -><A -NAME="AEN71" ->Plugin Return Codes</A -></H2 -><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 UNKOWN - return code.</P -><DIV -CLASS="TABLE" -><A -NAME="RETURNCODES" -></A -><P -><B ->Table 1. Plugin Return Codes</B -></P -><TABLE -BORDER="1" -BGCOLOR="#E0E0E0" -CELLSPACING="0" -CELLPADDING="4" -CLASS="CALSTABLE" -><THEAD -><TR -><TH -ALIGN="LEFT" -VALIGN="TOP" -><P ->Numeric Value</P -></TH -><TH -ALIGN="LEFT" -VALIGN="TOP" -><P ->Service Status</P -></TH -><TH -ALIGN="LEFT" -VALIGN="TOP" -><P ->Status Description</P -></TH -></TR -></THEAD -><TBODY -><TR -><TD -ALIGN="CENTER" -VALIGN="TOP" -><P ->0</P -></TD -><TD -ALIGN="LEFT" -VALIGN="MIDDLE" -><P ->OK</P -></TD -><TD -ALIGN="LEFT" -VALIGN="TOP" -><P ->The plugin was able to check the service and it - appeared to be functioning properly</P -></TD -></TR -><TR -><TD -ALIGN="CENTER" -VALIGN="TOP" -><P ->1</P -></TD -><TD -ALIGN="LEFT" -VALIGN="MIDDLE" -><P ->Warning</P -></TD -><TD -ALIGN="LEFT" -VALIGN="TOP" -><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" -VALIGN="TOP" -><P ->2</P -></TD -><TD -ALIGN="LEFT" -VALIGN="MIDDLE" -><P ->Critical</P -></TD -><TD -ALIGN="LEFT" -VALIGN="TOP" -><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" -VALIGN="TOP" -><P ->3</P -></TD -><TD -ALIGN="LEFT" -VALIGN="MIDDLE" -><P ->Unknown</P -></TD -><TD -ALIGN="LEFT" -VALIGN="TOP" -><P ->Invalid command line arguments were supplied to the - plugin or the plugin was unable to check the status of the given - hosts/service</P -></TD -></TR -></TBODY -></TABLE -></DIV -></DIV -></DIV -><DIV -CLASS="SECTION" -><HR><H1 -CLASS="SECTION" -><A -NAME="SYSCMDAUXFILES" ->System Commands and Auxiliary Files</A -></H1 -><DIV -CLASS="SECTION" -><H2 -CLASS="SECTION" -><A -NAME="AEN117" ->Don't execute system commands without specifying their - full path</A -></H2 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN121" ->Use spopen() if external commands must be executed</A -></H2 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN125" ->Don't make temp files unless absolutely required</A -></H2 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN128" ->Don't be tricked into following symlinks</A -></H2 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN131" ->Validate all input</A -></H2 -><P ->use routines in utils.c or utils.pm and write more as needed</P -></DIV -></DIV -><DIV -CLASS="SECTION" -><HR><H1 -CLASS="SECTION" -><A -NAME="PERLPLUGIN" ->Perl Plugins</A -></H1 -><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 - the first time and when Nagios 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 with ePN.</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 "$main::x" or predeclare every - variable. </P -><P ->Explicitly initialize each varialable in use. Otherwise with - caching enabled, the plugin will not be recompilied each time, and - therefore Perl will not reinitialize all the variables. All old - variable values will still be in effect.</P -></LI -><LI -><P ->Do not use < DATA > (these simply do not compile under ePN).</P -></LI -><LI -><P ->Do not use named subroutines</P -></LI -><LI -><P ->If writing to a file (perhaps recording - performance data) explicitly close close it. The plugin never - calls <I -CLASS="EMPHASIS" ->exit</I ->; that is caught by - p1.pl, so output streams are never closed.</P -></LI -><LI -><P ->As in <A -HREF="#RUNTIME" ->the section called <I ->Runtime Timeouts</I -></A -> all plugins need - to monitor their runtime, specially if they are using network - resources. Use of the <I -CLASS="EMPHASIS" ->alarm</I -> is recommended. - Plugins may import a default time out ($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><H1 -CLASS="SECTION" -><A -NAME="RUNTIME" ->Runtime Timeouts</A -></H1 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN165" ->Use DEFAULT_SOCKET_TIMEOUT</A -></H2 -><P ->All network plugins should use DEFAULT_SOCKET_TIMEOUT to timeout</P -></DIV -><DIV -CLASS="SECTION" -><HR><H2 -CLASS="SECTION" -><A -NAME="AEN168" ->Add alarms to network plugins</A -></H2 -><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><H1 -CLASS="SECTION" -><A -NAME="PLUGOPTIONS" ->Plugin Options</A -></H1 -><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><H2 -CLASS="SECTION" -><A -NAME="AEN174" ->Option Processing</A -></H2 -><P ->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).</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> - </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 -></DIV -><DIV -CLASS="SECTION" -><HR><H2 -CLASS="SECTION" -><A -NAME="AEN187" ->Plugins with more than one type of threshold, or with - threshold ranges</A -></H2 -><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 alternatves 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. 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.</P -></DIV -></DIV -><DIV -CLASS="SECTION" -><HR><H1 -CLASS="SECTION" -><A -NAME="SUBMITTINGCHANGES" ->New submissions and patches</A -></H1 -><P ->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.</P -><P ->Plugins in the contrib directory are going to be migrated to the - standard plugins/plugin-scripts directory as time permits and per user - requests</P -><P ->Patches should be submitted via the SourceForge and be announced to - the mailing list.</P -><P ->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.</P -><P ->If possible please submit a test harness. Documentation on sample - tests coming soon.</P -></DIV -></DIV -></DIV -></BODY -></HTML ->
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