first_notification_delay - notification may be sent too early

[Paweł Małachowski]

Hello,


according to manual:

first_notification_delay: This directive is used to define the number of
"time units" to wait before sending out the first problem notification when
this host enters a non-UP state. Unless you've changed the interval_length
directive from the default value of 60, this number will mean minutes. If
you set this value to 0, Nagios will start sending out notifications
immediately. 



However, it may send notification earlier, because time is counted starting
from last UP state, not first non-UP state.

Example:
passive check, first_notification_delay set to 60, passive checks reported
every 5 minutes:
00 minute - reported OK
05 minute - reported OK - the last OK status
10 minute - reported DOWN - notification won't be sent (delay in progress)
65 minute - notification sent (55 minutes after DOWN, not 60)
70 minute - no notification sent

If passive checks are reported less frequent, e.g. one per our, things get
even worse. :)



Code snippet for ilustration of this behaviour:

/* checks viability of sending a host notification */
int check_host_notification_viability(host *hst, int type, int options){
[...]
        if(type==NOTIFICATION_NORMAL && hst->current_notification_number==0 && hst->current_state!=HOST_UP && (current_time < (time_t)((hst->last_time_up==(time_t)0L)?program_start:hst->last_time_up + (hst->first_notification_delay*interval_length)))){
                log_debug_info(DEBUGL_NOTIFICATIONS,1,"Not enough time has elapsed since the host changed to a non-UP state (or since program start), so we shouldn't notify about this problem yet.\n");
                return ERROR;
                }

Probably using "last_state_change" instead of "last_time_up" would be better (haven't tried).



regards,
-- 
Paweł Małachowski

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