add graph for rear backup status

iml_rear_backup.ini

+; ======================================================================
+;
+; Rear Backup status
+;
+; ----------------------------------------------------------------------
+; 2023-12-22  <axel.hahn@unibe.ch>  initial version
+; ======================================================================
+
+; ----------------------------------------------------------------------
+; graph
+; ----------------------------------------------------------------------
+
+[backupserver.graph]
+check_command = "Rear-Backup"
+
+[backupserver.urlparams]
+areaAlpha   = "0.4"
+; areaMode    = "first"
+areaMode    = "stacked"
+colorList   = "cc0000,ffaa22,33cc33"
+;              ^      ^      ^
+;              crit   warn   ok
+
+lineWidth   = "2"
+min         = "0"
+; max         = "100"
+yUnitSystem = "binary"
+
+[backupserver.metrics_filters]
+critical   = "$service_name_template$.perfdata.critical.value"
+warning = "$service_name_template$.perfdata.warning.value"
+ok         = "$service_name_template$.perfdata.ok.value"
+
+[backupserver.functions]
+critical    = "alias($metric$, 'Outdated')"
+warning     = "alias($metric$, 'Warning')"
+ok          = "alias($metric$, 'OK')"