Is it possible to display the warning and critical treshold for example with a HLINE in RRDTool, without using PNP4Nagios?
I only found examples using PNP4Nagios to access the warning and critical values saved, but I am calling RRDTool from the command line and therefore I want to extract the warning and critical values using only this.
Any help appreciated.
To get a horizontal line added to the graph for your Critical threshold, you will need to use the HRULE directive to RRDgraph. E.G.:
HRULE:100#ff8080:Critical
However, you will need to extract the actual threshold values yourself from whatever software you are using (Nagios?) since RRDTool does not do thresholding itself. If you are generating your graphs using PNP4Nagios, then you can use the PNP4Nagios templates to pull the thresholds from Nagios and add the necessary line on the graph. Here's part of a PNP4Nagios template that pulls the Nagios threshold to use as part of the graph generation command:
if ($CRIT[1] != "") {
$def[1] .= "HRULE:$CRIT[1]#ff8080:Critical ";
}
If you are using RRDTool with MRTG, then the Routers2 frontend will add threshold lines to the generated graphs automatically if it finds a ThreshMaxI[] or similar definition.
If you do not use these, you'll need to obtain the threshold values yourself; remember RRDTool does not hold your threshold values, so it can only display these lines if you direct it to.
