Adding Munin plugin.

COPYING

-Copyright (c) 2009, 2010, 2011 Andreas Olsson
+Copyright (c) 2009-2012 Andreas Olsson
 
 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation

README

@@ -10,3 +10,9 @@ Nagios plugin which works by reading a text file containing a Unix
 timestamp of the most recent tarsnap backup. See the top comment in
 check_tarsnap for an example on how your tarsnap backup script can
 generate such a file.
+
+* tarsnap_usage
+This Munin plugin keeps track on how much data a machine has backed up
+on tarsnap. This is done by reading the current amount of data from a
+text file, preferably updated by the tarsnap backup script. See the
+plugin documentation for details.

tarsnap_usage

+#!/bin/sh
+# -*- sh -*-
+
+: << '=cut'
+
+=head1 NAME
+
+tarsnap_usage - Plugin to measure amount of tarsnap stored data
+
+=head1 CONFIGURATION
+
+By default the amount of data will be read from the file
+/var/lib/tarsnap/status/data. Another file can be specified by setting
+the variable datafile.
+
+  [tarsnap_usage]
+  env.datafile /path/to/datafile
+
+=head2 DATA FILE
+
+The plugin expects the data file to contain a numeric value, and
+nothing more, representing the number of bytes stored. One way to have
+that file generated is by running something like the following at the
+end of your tarsnap backup script.
+
+  data=$(tarsnap --print-stats | sed -nre "s/^\s+\(unique data\)\s+[0-9]+\s+([0-9]+)$/\1/p")
+  [ -n "$data ] && echo "$data" > /var/lib/tarsnap/status/data
+
+=head1 AUTHOR
+
+Andreas Olsson <andreas@arrakis.se>
+
+=head1 LICENSE
+
+MIT License
+
+=head1 MAGIC MARKERS
+
+ #%# family=auto
+ #%# capabilities=autoconf
+
+=cut
+
+if [ -z "$datafile" ]; then
+    datafile="/var/lib/tarsnap/status/data"
+fi
+
+amount=$(cat "$datafile" 2> /dev/null)
+
+is_numeric () {
+    echo "$amount" | grep -Eq "^[0-9]+$" && return 0 || return 1
+}
+
+if [ "$1" = "autoconf" ]; then
+    is_numeric && echo yes || echo no
+    exit 0
+fi
+
+if [ "$1" = "config" ]; then
+    echo 'graph_title Tarsnap usage'
+    echo 'graph_vlabel byte stored'
+    echo 'data.label total usage'
+    echo 'graph_args --base 1000 -l 0'
+    echo 'graph_category disk'
+    echo 'graph_info Total amount of unique data backed up by tarsnap. That is, after deduplication and compression.'
+    exit 0
+fi
+
+if ! is_numeric; then
+    echo "Failed to read expected data from ${datafile}"
+    exit 1
+fi
+
+echo "data.value ${amount}"