Nagios Support Forum

## Summary

In Nagios Core 4.4.14 (on AlmaLinux 9.5, installed via YUM), we are encountering a problem where service notifications are not sent after state transitions like:

`CRITICAL → OK → CRITICAL`

Only the first CRITICAL state triggers a notification. After recovery (OK), if the service becomes CRITICAL again, no notification is sent.

## Expected Behavior

We want Nagios to trigger a service notification (and execute our custom notification script) **every time** the service enters a HARD state like CRITICAL — even if it was previously in CRITICAL before recovering.

## Actual Behavior

- Initial state change from OK to CRITICAL → notification sent
- Recovery to OK → notification sent
- State changes back to CRITICAL → **no notification sent**
- No `SERVICE NOTIFICATION` log is recorded in `/var/log/nagios/nagios.log`.

## Notification Script

The custom script we are using is:

```bash
#!/bin/bash
#$1:HOSTADDRESS
#$2:HOSTALIAS
#$3:SERVICESTATE
#$4:CONTACTEMAIL

if [ "${3}" == "OK" ]; then
Stat="IF-UP"
else
Stat="IF-DOWN"
fi

/usr/bin/printf "%b" "Event: ${Stat}\nIpAddress: ${1}\nHost: ${2}\n" | /usr/bin/mail -r [email protected] -s "${Stat} ${1}" ${4}


※(We replaced actual email addresses with [email protected] for privacy.)

◆Configuration Summary
〇services.cfg

define service{
name generic-service
active_checks_enabled 1
passive_checks_enabled 1
parallelize_check 1
obsess_over_service 1
check_freshness 0
notifications_enabled 1
event_handler_enabled 1
flap_detection_enabled 1
process_perf_data 1
retain_status_information 1
retain_nonstatus_information 1
is_volatile 0
check_period 24x7
max_check_attempts 3
check_interval 30
retry_interval 1
contact_groups ADMING001
notification_options w,u,c,r
notification_interval 0
notification_period 24x7
register 0
}
define service{
use generic-service
host_name TEST001
service_description TESTS001
check_command check_ping!1000.0,80%!2000.0,100%
check_interval 2
retry_interval 1
}
〇contacts.cfg

define contact {
contact_name ADMIN001
use generic-contact
service_notification_options u,c,r
host_notification_options n
service_notification_commands send-alarm2
host_notification_commands send-alarm2
email [email protected]
}
〇commands.cfg

define command {
command_name send-alarm2
command_line /usr/local/nagios/libexec/send-alarm2.sh $HOSTADDRESS$ $HOSTALIAS$ $SERVICESTATE$ $CONTACTEMAIL$
}


◆Question
Is this behavior expected?

How can we configure Nagios so that it sends notifications on every state change, even if it's a reoccurrence of the same state?

Hello @hayaken9999,

You may want to adjust your notification_interval as I believe setting that to 0 will prevent re-notifications.

You may also want to look into setting your service as volatile. Take a look at the following:
https://assets.nagios.com/downloads/nag ... vices.html

Thank you for your suggestions regarding notification_interval and is_volatile.

However, I would like to clarify the actual issue we're facing:

CRITICAL → OK → CRITICAL
A notification is sent for the first CRITICAL state and for the recovery (OK), but no notification is sent when the state returns to CRITICAL after recovery.
This is the core of the problem.

Here are the current configuration details:

notification_interval=0 is already set, so we do not expect repeated notifications while in the same CRITICAL state.

What we do need is a notification only when the service state changes, such as:

CRITICAL → OK → CRITICAL (each transition should trigger a notification).

is_volatile=0 is set for the service.
If we set is_volatile=1, then alerts appear in the Nagios UI, but no emails are sent.

notifications_enabled=1 is confirmed.

Given these conditions, what can we do to ensure that Nagios sends notifications on every state change, especially for transitions like CRITICAL → OK → CRITICAL?

We appreciate your continued support.

Best regards,

The state changes may not be as you think depending upon your setup.

The state may go from:

CRITICAL(Hard) → OK(Hard) → CRITICAL(Soft) -> CRITICAL(Hard)

Alerts are sent at each transition (if configured) but notifications are only sent when it transition to "Hard".