Category Archives: nagios

How to send passive checks to nagios real life example:

Posted by on January 13, 2016 No comments

First of all – why you need to use passive checks in nagios.
It`s useful for large systems, nagios will not wait for connect timeout during telecom issues.
And it`s easy to configure.

Our case (large social network).
Need to check number of unsubscribers. If no “unsubscribe” letters for 1 hour – something goes wrong… FBL list not working and we need Alert. If we will not process FBL letters for several hours, email providers rise our SPAM rating.

How to fetch letters (I use ruby Imap) – topic for another article :).

1. Nagios Check code:

# cat /home/scripts/fbl.sh
#!/bin/bash

NUM=`/usr/bin/psql -t -h 1.1.1.1 -p 5450 -U cron_user  base3 -c "select count(1) from email_stop_list where (esl_created BETWEEN current_timestamp - interval '1 hour' and current_timestamp) and esl_reason ~ '^fbl'"`

if [ $NUM -eq 0 ]; then
        echo -e "nest\tunsubscribe_fbl\t3\tNo_Unsubscribe"  | /home/scripts/send_nsca -H 2.2.2.2 -p 5667 -c /etc/send_nsca.conf
 else
    echo -e "nest\tunsubscribe_fbl\t0\t$NUM unsubscribes last houer"  | /home/scripts/send_nsca -H 2.2.2.2 -p 5667 -c /etc/send_nsca.conf
 fi

2. Code for send_nsca

Plugin Return Code Service State Host State
0 OK UP
1 WARNING UP or DOWN/UNREACHABLE*
2 CRITICAL DOWN/UNREACHABLE
3 UNKNOWN DOWN/UNREACHABLE

3. Nginx service config

# cat nest.cfg
define service{
  use                            generic-service-template-passive
  host_name                       nest
  service_description             unsubscribe_fbl
  freshness_threshold             3600
  check_command                   volatile_no_information
  contact_groups                  nagios-wheel,nagios-wheel-smsmail
}

4. Service template

define service {
    use                             generic-service-template
    name                            generic-service-template-passive
    active_checks_enabled           0
    passive_checks_enabled          1
    obsess_over_service             0
    flap_detection_enabled          0
    event_handler_enabled           1
    failure_prediction_enabled      1
    is_volatile                     1
    register                        0
    check_period                    24x7
    max_check_attempts              1
    normal_check_interval           5
    retry_check_interval            2
    check_freshness                 1
    freshness_threshold             90000
    contact_groups                  nagios-wheel
    check_command                   volatile_no_information
    notifications_enabled           1
    notification_interval           15
    notification_period             24x7
    notification_options            w,u,c,r
    process_perf_data               1
    retain_status_information       1
    retain_nonstatus_information    1
}