Recurring Downtimes
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## Recurring Downtimes

Many people have regular downtimes at different times and it would be a tedious task to reschedule them manually every time. So far there is no official format for defining such schedules. That means that these definitions have to be stored in a separate file which cannot be included into the other object definitions. A cronjob will call a script which will read the definitions, already existing downtimes, and plan new downtimes if necessary.

Downtime definition

Icinga introduces a new format for these downtimes based on existing definitions taken from the status file and time periods resulting in:

     define downtime {
        host_name           some host
        hostgroups          some hostgroup
        servicegroups       some servicegroup
        service_description some service
        author              some author
        comment             some comment
        duration            30
        downtime_period     2011-10-02 - 2011-10-10 10:00-12:00
        fixed               0
        propagate           1
        register            0
    }

Notes on the above definition:

- "host_name", "hostgroups", and "servicegroups" are mandatory and mutually exclusive.

- "service_description" is optional. If not defined a downtime for a host / hostgroup(s) / servicegroup(s) is/are scheduled. If defined it can be a single service or "all" for all services of a single host or all hosts of a hostgroup.

- "duration" is optional and must be defined if a flexible downtime is to be scheduled.

- "fixed" is optional and will be "0" if duration is defined or if it differs from start time-end time.

- "propagate" is optional and defaults to "0". If set the downtime will be propagated to child hosts of the host specified.

- "register" may be used to deactive the definition ("0"). It will have the same effect as if the definition would not exist.

- "downtime_period" is similar to the definition found in time periods meaning that any of the following should be valid:

         downtime_period     2011-10-01              20:00-02:00
         downtime_period     2011-10-10 - 2011-10-20 10:00-12:00
         downtime_period     day 1 - 3               04:00-12:00
         downtime_period     sunday                  00:00-24:00
         downtime_period     monday - wednesday      20:00-22:00
         downtime_period     monday                  00:00-09:00,17:00-24:00
         downtime_period     1999-01-28              00:00-24:00
         downtime_period     saturday                00:00-24:00
         downtime_period     monday 3                00:00-24:00
         downtime_period     day 2                   00:00-24:00
         downtime_period     february 10             00:00-24:00
         downtime_period     february -1             00:00-24:00
         downtime_period     friday -2               00:00-24:00
         downtime_period     thursday -1 november    00:00-24:00
         downtime_period     2007-01-01 - 2008-02-01 00:00-24:00
         downtime_period     monday 3 - thursday 4   00:00-24:00
         downtime_period     day 1 - 15              00:00-24:00
         downtime_period     day 20 - -1             00:00-24:00
         downtime_period     july 10 - 15            00:00-24:00
         downtime_period     april 10 - may 15       00:00-24:00
         downtime_period     tuesday 1 april - friday 2 may      00:00-24:00
         downtime_period     2007-01-01 - 2008-02-01 / 3         00:00-24:00
         downtime_period     2008-04-01 / 7                      00:00-24:00
         downtime_period     monday 3 - thursday 4 / 2           00:00-24:00
         downtime_period     day 1 - 15 / 5                      00:00-24:00
         downtime_period     july 10 - 15 / 2                    00:00-24:00
         downtime_period     tuesday 1 april - friday 2 may / 6  00:00-24:00

  Please note that similiar to time periods multiple "downtime_period" entries per definition are possible to define different times for a single object like the following:

       define downtime {
          ...
          comment            Backup: incr on wed, full on sat
          downtime_period    wednesday 20:00-21:00
          downtime_period    saturday  20:00-23:30
      }

  Well, there is one drawback. This way you cannot define different flexible downtimes within one definition.

Variable dates

The definitions above will work for most dates but some are calculated based on easter sunday which is on a different date each year. We tried to bypass these limitations by calculating the dates based on easter sunday and giving them names you can refer to. The variable names are not case sensitive.

Variable name | Offset / Date
--- | ---
Twelfth_day | January, 6th
Labour_day | May, 1st
Carnival_monday | -48
Mardi_gras | -47
Ash_wednesday | -46
Maundy_thursday | -3
Good_friday | -2
Easter_sunday | 0
Easter_monday | 1
Ascension_day | +39
Whit_sunday | +49
Whit_monday | +50
Trinity | +56
Corpus_christi | +70
Assumption_day | August, 8th
Penance_day | Wednesday before Nov., 23rd
Christmas_day | December, 25th
Boxing_day | December, 26th

So now you can define a downtime for Carnival Monday using something like:

     define downtime {
        ...
        comment            Cheer up, lads
        downtime_period    carnival_monday 09:00-17:00
     }

Local holidays

Looking at the calendars of several countries there are a lot of holidays which only apply to a single country. Unfortunately some of these dates are on a weekday in a week within a month. You can already define these dates using "monday 3 february" or "monday -1 may" but you may want to use variables names as well. Defining these names and their corresponding calculations in a separate file and processing them enables you to do so. The default name for this file is `holiday.cfg` located in `/usr/local/icinga/etc`. The location can be altered using the option "-l".

We only picked three dates to give you the idea how to do it:

    # example of local holiday definitions
    # please don't use local characters
    # variable names must not contain spaces
    #
    Presidents_day        day_in_week_of_month(2,1,3)
    Spring_Bank_Holiday   day_in_week_of_month(5,1,-1)
    Pentecote             date_easter(49)

There are two "functions" available to define these flexible dates:

- "day_in_week_of_month": You have to specify three parameters

  - month: 1 = january ... 12 = december

  - day: 1 = monday ... 7 = sunday

  - week: 1 .. 5 for the week within the month or -1 for last week within the month

- "date_easter": The number specifies the offset from easter sunday

So now you can define a downtime using something like:

     define downtime {
        ...
        comment            Don't shut down the cash machines
        downtime_period    spring_bank_holiday  09:00-17:00
     }

Please note that you have to specify the location of this file using the option "-l".

Entering downtimes

So far there is no way to enter the definitions via your browser so you have to use your favourite text editor to create the definitions. Sorry.

Planning downtimes

Once you have created a file holding the downtime definitions you will want to schedule the downtimes automatically. This can be done using the Perl script "sched_down.pl" being called from the crontab. The script itself requires the Perl module "Date::Calc".

The easiest way is to execute "/path/to/script/sched_down.pl". Adding the option "-h" will output some information:

       -c | --config=s     Icinga main config
                           default: /usr/local/icinga/etc/icinga.cfg
       -s | --schedule=s   schedule definitions
                           default: /usr/local/icinga/etc/downtime.cfg
       -l | --local=s      local holiday definitions
                           default: /usr/local/icinga/etc/holiday.cfg
       -m | --max_ahead=s  plan max. days ahead (default = 2)
       -f | --forecast=s   forecast next schedules
       -e | --examine=s    examine period and show next schedule
                           specify date and time instead like in downtime_period
       -t | --timestamp=s  specify deviating date/time
                           YYYYMMDDhhmi, YYYYMMDD, or hhmi
       -d | --debug=s      0|1|2|3 (default = 1)
       -h | --help         display this help

    Note: Enabled debugging, forecasting, and/or examine will prevent that schedules
          are sent to the command pipe (downtimes are only calculated)!

    Setting environment variables influences the behaviour:
    - FAKE_DATE (YYYYMMDD): date deviating from current date
    - FAKE_TIME (HHMM)    : time deviating from current time
    - DEBUG (0|1|2|3)     : disables/enables debugging information
      0 = no debugging / cmds are sent to external command pipe!
      Note: command line options take precedence over environment variables

All arguments are optional. Just to test the function of the script it might be helpful to use the "examine" option followed by a downtime period:

     /usr/local/icinga/bin/sched_down.pl -e "tuesday 20:00-21:00"

This will return a string similar to the actual command if the downtime is within the planning period (default two days) which can be altered using the option "-m". To test downtimes in the future you may set the environment variable FAKE_DATE (e.g. "FAKE_DATE=20130127") prior calling the script although it might be easier to use the option "-t".

There are two ways to execute the script:

- As an active check

  You can execute the script like a normal active check with a convenient check interval

       define service {
          host_name             icinga-server
          service_description   schedule_downtimes
          check_command         schedule_script!-d0
          check_interval        60
          retry_interval        60
          check_period          24x7
          ...
       }

       define command {
          command_name          schedule_script
          command_line          $USER1$/sched_down.pl $ARG1$
       }

- Via the crontab

  A line in the crontab of the Icinga user executing the script every full hour might look like

       0 * * * * /usr/local/icinga/bin/sched_down.pl -d0

Unless you get the downtimes on short notice this should be sufficient. The script will only plan non-existing downtimes so no harm will be done if it is called more often.

Converting downtime definitions

Steve Shipway has created files to plan downtimes via a CGI and schedule them for several Nagios versions a long time ago (see here).

The commercial Nagios version has added recurring downtimes as well but instead of using all of Steve's scripts they decided to take the scheduling script and write a new CGI which doesn't seem to be able to plan flexible downtimes (well, at least not in the 2011 VM).

The Perl script "sched_conv.pl" will try to convert files created by these two scripts mentioned above into a new file. You may want to call the script adding the option "-h" to get some help.

Files

You will find the perl scripts in `contrib/downtimes`.

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