check-disk-usage.rb - Option to define minimal free space threshold

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This CHANGELOG follows the format listed [here](https://github.com/sensu-plugins/community/blob/master/HOW_WE_CHANGELOG.md)
 
 ## [Unreleased]
+### Added
+- `check-disk-usage.rb` - Option to define minimal free space threshold.
 
 ## [5.1.4] - 2020-11-05
 ### Fixed

README.md

@@ -55,6 +55,7 @@ Usage: check-disk-usage.rb (options)
     -m MAGIC                         Magic factor to adjust warn/crit thresholds. Example: .9
     -l MINIMUM                       Minimum size to adjust (in GB)
     -n NORMAL                        Levels are not adapted for filesystems of exactly this size, where levels are reduced for smaller filesystems and raised for larger filesystems.
+    -f FREESPACEBELOW                Trigger warn/critical alarm only if free space on mount goes below this threshold (in GB). Useful on huge filesystems which are 99.X percent full and still have lots of space left.
 ```
 
 **metrics-disk-usage.rb**

bin/check-disk-usage.rb

@@ -122,6 +122,13 @@ class CheckDisk < Sensu::Plugin::Check::CLI
          proc: proc(&:to_f),
          default: 100
 
+  option :freespacebelow,
+         short: '-f FREESPACEBELOW',
+         description: 'Trigger alarm only if free space on device is below '\
+           'this threshold (in GB)',
+         proc: proc(&:to_f),
+         default: 10000
+
   # Setup variables
   #
   def initialize
@@ -195,10 +202,12 @@ def check_mount(line)
     used = to_human(fs_info.bytes_used)
     total = to_human(fs_info.bytes_total)
 
-    if percent_b >= bcrit
-      @crit_fs << "#{line.mount_point} #{percent_b}% bytes usage (#{used}/#{total})"
-    elsif percent_b >= bwarn
-      @warn_fs << "#{line.mount_point} #{percent_b}% bytes usage (#{used}/#{total})"
+    if (fs_info.bytes_total - fs_info.bytes_used) <= (config[:freespacebelow] * 1_000_000_000)
+      if percent_b >= bcrit
+        @crit_fs << "#{line.mount_point} #{percent_b}% bytes usage (#{used}/#{total})"
+      elsif percent_b >= bwarn
+        @warn_fs << "#{line.mount_point} #{percent_b}% bytes usage (#{used}/#{total})"
+      end
     end
   end