As some people know, I previously " created" (mostly modified the check_swap plug-in to print RAM usage) check_ram in C. Now one of my problems for the past few months was putting the C plug-in as well as " supported" environment under the same hat. Today I had another look at the amount of available plug-ins in NagiosExchange. There are quite a few plug-ins available, but as I do have some experience with Python, I used the one written in Python.

It was rather easy hacking in support for performance data into it, as the below shows. Someone else already posted a non-unified diff for performance data support, but that ain’t quite right according to the Nagios plug-in development guidelines.

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--- check_ram.py.orig
+++ check_ram.py
@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 #
 #   Copyright Hari Sekhon 2007
+#   Copyright Christian Heim 2008
 #
 #   This program is free software; you can redistribute it and/or modify
 #   it under the terms of the GNU General Public License as published by
@@ -64,27 +65,30 @@
     total_used_megs = float(memtotal-memfree) / 1024
     total_free_megs = float(total_free) / 1024
     memtotal_megs   = float(memtotal) / 1024
+
+    total_warning_threshold_megs = round(float(memtotal) * float(warning_threshold) / 100 / 1024)
+    total_critical_threshold_megs = round(float(memtotal) * float(critical_threshold) / 100 / 1024)

     if percent == True:
         percentage_free = int( float(total_free) / float(memtotal) * 100 )
         if percentage_free < critical_threshold:
-            print "RAM CRITICAL: %d%% ram free (%d/%d MB used)" % (percentage_free,total_used_megs,memtotal_megs)
+            print "RAM CRITICAL - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)
             return CRITICAL
         elif percentage_free < warning_threshold:
-            print "RAM WARNING: %d%% ram free (%d/%d MB used)" % (percentage_free,total_used_megs,memtotal_megs)
+            print "RAM WARNING - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)
             return WARNING
         else:
-            print "RAM OK: %d%% ram free" % percentage_free
+            print "RAM OK - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)
             return OK
     else:
         if total_free < critical_threshold:
-            print "RAM CRITICAL: %dMB ram free (%d/%d MB used)" % (total_free_megs,total_used_megs,memtotal_megs)
+            print "RAM CRITICAL - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)
             return CRITICAL
         if total_free < warning_threshold:
-            print "RAM WARNING: %dMB ram free (%d/%d MB used)" % (total_free_megs,total_used_megs,memtotal_megs)
+            print "RAM WARNING - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)
             return WARNING
         else:
-            print "RAM OK: %dMB ram free" % (total_free_megs)
+            print "RAM OK - %d%% free (%d MB out of %d MB) |ram=%dMB;%d;%d;0;%d" % (percentage_free,total_free_megs,memtotal_megs,total_free_megs,total_warning_threshold_megs,total_critical_threshold_megs,memtotal_megs)

             return OK

Now, with that simple plug-in I can go ahead and package the thing separately, without the need to figure out a way to get them nagios-plugins to install some useful includes …