Configuration

Setting up environment
Setting up check-command
Defining services
Creating RRD's
Configuring Apan
Adding an icond and a link
Debugging

Setting up environment

Modify apan.defs to suit your needs. If Apan is installed in another location than /usr/local/nagios/apan, you have to set the path to apan.defs in apan.sh, apan.cgi and generate.cgi.

Setting up check-command

Define a check-command for apan in checkcommands.cfg;

define command {
command_name                   apan
command_line                   /usr/local/nagios/apan/apan.sh $ARG1$ $HOSTNAME$ $SERVICEDESC$ $TIMET$ $ARG2$ $ARG3$
}

Defining services

Set up the services that will do the monitoring;

define service {
host_name                      sheriff,bandit,WC-router-holland
service_description            Ping
check_command                  apan!ping!100.0,20%!500.0,60%
name                           Ping
use                            generic-service
normal_check_interval          1
}

define service {
host_name                      sheriff,pistol,barbar
service_description            Statd-load
check_command                  apan!load!70!90
use                            generic-test
normal_check_interval          1
}

Note:

The second argument in the check_command is the name of the plugin that apan will use. Read more about each plugin in next section of the docs.
The third and fourth argument is used by the plugins, mainly to specify warning and critical levels.

Creating RRD's

I am no expert on RRD-tool, so maybe these examples are not so optimized.. For example:

 rrdtool create /usr/local/nagios/rrd/raket_Net-use.rrd -s 60 DS:IN:COUNTER:300:0:U DS:OUT:COUNTER:300:U:U RRA:AVERAGE:0.5:1:50400 RRA:AVERAGE:0.5:60:43800

Creates an RRD with two datasets named IN and OUT. The datasets are counters supposed to store the number of network packages sent and received on a network-interface. Samplerate is one minute and RRA's are set up to store minut-average for 35 days and hour-average for 5 years.

To store Pig round-trip times you can use the same syntax, but change the DS-type to 'GAUGE';

rrdtool create /usr/local/nagios/rrd/bandit-ping.rrd -s 60 DS:ping:GAUGE:300:0:U RRA:AVERAGE:0.5:1:50400 RRA:AVERAGE:0.5:60:43800

The thing you probably want to look more at is the samplerate and heartbeat values.
Read more about RRD-tool at http://people.ee.ethz.ch/~oetiker/webtools/rrdtool

Configuring Apan

Now its time for the hard step, the config-file apan.cfg. For each service you want apan to handle you must add a line in apan.cfg. The line is made up of 8 fields separated by ';'.
The fields are:

Host name ; Service name ; RRD-file ; argument-1|argument-2|..argument-n ; DS-name-1:plot-function-1 DS-name-2:plot-function-2 DS-name-n:plot-function-n ; Comment ; Y-unit ; Extra command

In more detail:

Host name

The name of the host, should be exactly the same name as in Nagios.

Service name

The name of the service, should be exactly the same name as in Nagios.

RRD-file

Full name of the RRD-file including the full path.

argument-1|argument-2|..argument-n

Arguments to be used by the plugin. The plugin will be called one time for each argument. Arguments can contain any character exept '|'.

DS-name-1:plot-function-1 DS-name-2:plot-function-2 DS-name-n:plot-function-n

DS-name is the name of the dataset that corresponds to the argument in the previous field. Plot-function is the format that rrdtool will use to plot the corresponding dataset when the graphs are constructed.

Comment

An additional informativ string that is displayed on the we-page with the graphs.

Y-unit

The unit displayed on the Y-axis in the graphs.

Extra command

Here you can define extra command-line arguments that will be used by rrdtool when the graps are created.

OK, that's the theoretical part, maybe some examples could help?

barbar;apan-disk;/usr/local/nagios/rrd/barbar_disk.rrd;/;-:LINE2;Disk-usage;%

This line defines the service 'apan-disk' for host 'barbar'. The RRD, /usr/local/nagios/rrd/barbar_disk.rrd, have one DS named '-'. The plugin is called once with the argument '/'. When a graph is plotted, LINE2 (a medium-thick line) is used for drawing and the Y-axis is labeled '%'.

sdl-www-01;Network-10;/usr/local/nagios/rrd/sdl-www-01_Network-10.rrd;public:.1.3.6.1.2.1.2.2.1.10.16777220|public:.1.3.6.1.2.1.2.2.1.16.16777220;10_IN:LINE2 10_OUT:LINE2;Network throughput;Bytes/sek;

In this definition, the RRD have two datasets named '10_IN' and '10_OUT'. The plugin is called twice with the arguments 'public:.1.3.6.1.2.1.2.2.1.10.16777220' and 'public:.1.3.6.1.2.1.2.2.1.16.16777220' (The SNMP oid's for sent and received network packages).

adsrv;Disk-usage;/usr/local/nagios/rrd/adsrv_disk.rrd;c;c-used:AREA c-free:STACK;Disk usage;Bytes;-l 1 -b 1024

Here, the RRD have the datasets 'c-used' and 'c-free'. The plugin is called once wit the argument 'c'. When we generate a graph for this data, 'c-used' will become a filled area with 'c-free' stacked upon it. When the y-axis is scaled, 1024 will be used as base-value and it will always start from 0 (-l 1 -b 1024 in the 'Extra command'-field).

Simple?? For more information on the arguments, DS-values, etc - look at the plugin-documentation for the specific plugin used.

Adding an icon and a link

In order to access the graphs from Nagios web-interface you have to add a link to the service as an 'Extendet service information' (see Nagios docs for more information).
Add a seviceextinfo with graph.png as 'icon_image' and point 'notes_url' to apan.cgi with host-name and service-name as arguments. Example:

define serviceextinfo{
host_name               server
service_description     Ping
notes_url               /nagios/cgi-bin/apan.cgi?host=server&service=Ping
icon_image              graph.png
icon_image_alt          View graphs
}

Debugging

To enable debugging output from Apan, set the variables DEBUG to 1 and the variable DEBUGFILE to point to a file in apan.defs; Debugging output from the cgi's ic controlled by CGIDEBUG and CGIDEBUGFILE

DEBUG=1
DEBUGFILE=/tmp/apan.debug
CGIDEBUG=1
CGIDEBUGFILE=/tmp/apancgi.debug

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