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Elasticsearch Guide [7.7] » Alerting on cluster and index events » Triggers » Schedule trigger
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Schedule triggeredit

Schedule triggers define when the watch execution should start based on date and time. All times are specified in UTC time.

Watcher uses the system clock to determine the current time. To ensure schedules are triggered when expected, you should synchronize the clocks of all nodes in the cluster using a time service such as NTP.

Keep in mind that the throttle period can affect when a watch is actually executed. The default throttle period is five seconds (5000 ms). If you configure a schedule that’s more frequent than the throttle period, the throttle period overrides the schedule. For example, if you set the throttle period to one minute (60000 ms) and set the schedule to every 10 seconds, the watch is executed no more than once per minute. For more information about throttling, see Acknowledgement and throttling.

Watcher provides several types of schedule triggers:

Hourly scheduleedit

A schedule that triggers at a particular minute every hour of the day. To use the hourly schedule, you specify the minute (or minutes) when you want the scheduler to start the watch execution with the minute attribute.

If you don’t specify the minute attribute for an hourly schedule, it defaults to 0 and the schedule triggers on the hour every hour--12:00, 13:00, 14:00, and so on.

Configuring a once an hour scheduleedit

To configure a once an hour schedule, you specify a single time with the minute attribute.

For example, the following hourly schedule triggers at minute 30 every hour-- 12:30, 13:30, 14:30, …​:

{
  "trigger" : {
    "schedule" : {
      "hourly" : { "minute" : 30 }
    }
  }
}

Configuring a multiple times hourly scheduleedit

To configure an hourly schedule that triggers at multiple times during the hour, you specify an array of minutes. For example, the following schedule triggers every 15 minutes every hour--12:00, 12:15, 12:30, 12:45, 1:00, 1:15, …​:

{
  "trigger" : {
    "schedule" : {
      "hourly" : { "minute" : [ 0, 15, 30, 45 ] }
    }
  }
}

Daily scheduleedit

A schedule that triggers at a particular time every day. To use the daily schedule, you specify the time of day (or times) when you want the scheduler to start the watch execution with the at attribute.

Times are specified in the form HH:mm on a 24-hour clock. You can also use the reserved values midnight and noon for 00:00 and 12:00, and specify times using objects.

If you don’t specify the at attribute for a daily schedule, it defaults to firing once daily at midnight, 00:00.

Configuring a daily scheduleedit

To configure a once a day schedule, you specify a single time with the at attribute. For example, the following daily schedule triggers once every day at 5:00 PM:

{
  "trigger" : {
    "schedule" : {
      "daily" : { "at" : "17:00" }
    }
  }
}

Configuring a multiple times daily scheduleedit

To configure a daily schedule that triggers at multiple times during the day, you specify an array of times. For example, the following daily schedule triggers at 00:00, 12:00, and 17:00 every day.

{
  "trigger" : {
    "schedule" : {
      "daily" : { "at" : [ "midnight", "noon", "17:00" ] }
    }
  }
}

Specifying times using objectsedit

In addition to using the HH:mm string syntax to specify times, you can specify a time as an object that has hour and minute attributes.

For example, the following daily schedule triggers once every day at 5:00 PM:

{
  "trigger" : {
    "schedule" : {
      "daily" : {
        "at" : {
          "hour" : 17,
          "minute" : 0
        }
      }
    }
  }
}

To specify multiple times using the object notation, you specify multiple hours or minutes as an array. For example, following daily schedule triggers at 00:00, 00:30, 12:00, 12:30, 17:00 and 17:30 every day:

{
  "trigger" : {
    "schedule" : {
      "daily" : {
        "at" : {
          "hour" : [ 0, 12, 17 ],
          "minute" : [0, 30]
        }
      }
    }
  }
}

Weekly scheduleedit

A schedule that triggers at a specific day and time every week. To use the weekly schedule, you specify the day and time (or days and times) when you want the scheduler to start the watch execution with the on and at attributes.

You can specify the day of the week by name, abbreviation, or number (with Sunday being the first day of the week):

  • sunday, monday, tuesday, wednesday, thursday, friday and saturday
  • sun, mon, tue, wed, thu, fri and sat
  • 1, 2, 3, 4, 5, 6 and 7

Times are specified in the form HH:mm on a 24-hour clock. You can also use the reserved values midnight and noon for 00:00 and 12:00.

Configuring a weekly scheduleedit

To configure a once a week schedule, you specify the day with the on attribute and the time with the at attribute. For example, the following weekly schedule triggers once a week on Friday at 5:00 PM:

{
  "trigger" : {
    "schedule" : {
      "weekly" : { "on" : "friday", "at" : "17:00" }
    }
  }
}

You can also specify the day and time with the day and time attributes, they are interchangeable with on and at.

Configuring a multiple times weekly scheduleedit

To configure a weekly schedule that triggers multiple times a week, you can specify an array of day and time values. For example, the following weekly schedule triggers every Tuesday at 12:00 PM and every Friday at 5:00 PM:

{
  "trigger" : {
    "schedule" : {
      "weekly" : [
        { "on" : "tuesday", "at" : "noon" },
        { "on" : "friday", "at" : "17:00" }
      ]
    }
  }
}

Alternatively, you can specify days and times in an object that has on and minute attributes that contain an array of values. For example, the following weekly schedule triggers every Tuesday and Friday at 12:00 PM and 17:00 PM:

{
  "trigger" : {
    "schedule" : {
      "weekly" : {
        "on" : [ "tuesday", "friday" ],
        "at" : [ "noon", "17:00" ]
      }
    }
  }
}

Monthly scheduleedit

A schedule that triggers at a specific day and time every month. To use the monthly schedule, you specify the day of the month and time (or days and times) when you want the scheduler to start the watch execution with the on and at attributes.

You specify the day of month as a numeric value between 1 and 31 (inclusive). Times are specified in the form HH:mm on a 24-hour clock. You can also use the reserved values midnight and noon for 00:00 and 12:00.

Configuring a monthly scheduleedit

To configure a once a month schedule, you specify a single day and time with the on and at attributes. For example, the following monthly schedule triggers on the 10th of each month at noon:

{
  "trigger" : {
    "schedule" : {
      "monthly" : { "on" : 10, "at" : "noon" }
    }
  }
}

You can also specify the day and time with the day and time attributes, they are interchangeable with on and at.

Configuring a multiple times monthly scheduleedit

To configure a monthly schedule that triggers multiple times a month, you can specify an array of day and time values. For example, the following monthly schedule triggers at 12:00 PM on the 10th of each month and at 5:00 PM on the 20th of each month:

{
  "trigger" : {
    "schedule" : {
      "monthly" : [
        { "on" : 10, "at" : "noon" },
        { "on" : 20, "at" : "17:00" }
      ]
    }
  }
}

Alternatively, you can specify days and times in an object that has on and at attributes that contain an array of values. For example, the following monthly schedule triggers at 12:00 AM and 12:00 PM on the 10th and 20th of each month.

{
  "trigger" : {
    "schedule" : {
      "monthly" : {
        "on" : [ 10, 20 ],
        "at" : [ "midnight", "noon" ]
      }
    }
  }
}

Yearly scheduleedit

A schedule that triggers at a specific day and time every year. To use the yearly schedule, you specify the month, day, and time (or months, days, and times) when you want the scheduler to start the watch execution with the in, on, and at attributes.

You can specify the month by name, abbreviation, or number:

  • january, february, march, april, may, june, july, august, september, october, november and december
  • jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov and dec
  • 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12

You specify the day of month as a numeric value between 1 and 31 (inclusive). The Times are specified in the form HH:mm on a 24-hour clock. You can also use the reserved values midnight and noon for 00:00 and 12:00.

Configuring a yearly scheduleedit

To configure a once a year schedule, you specify the month with the in attribute, the day with the on attribute, and the time with the at attribute. For example, the following yearly schedule triggers once a year at noon on January 10th:

{
  "trigger" : {
    "schedule" : {
      "yearly" : { "in" : "january", "on" : 10, "at" : "noon" }
    }
  }
}

You can also specify the month, day, and time with the month, day, and time attributes, they are interchangeable with in, on, and at.

Configuring a multiple times yearly scheduleedit

To configure a yearly schedule that triggers multiple times a year, you can specify an array of month, day, and time values. For example, the following yearly schedule triggers twice a year: at noon on January 10th, and at 5:00 PM on July 20th.

{
  "trigger" : {
    "schedule" : {
      "yearly" : [
        { "in" : "january", "on" : 10, "at" : "noon" },
        { "in" : "july", "on" : 20, "at" : "17:00" }
      ]
    }
  }
}

Alternatively, you can specify the months, days, and times in an object that has in, on, and minute attributes that contain an array of values. For example, the following yearly schedule triggers at 12:00 AM and 12:00 PM on January 10th, January 20th, December 10th, and December 20th.

{
  "trigger" : {
    "schedule" : {
      "yearly" : {
        "in" : [ "jan", "dec" ],
        "on" : [ 10, 20 ],
        "at" : [ "midnight", "noon" ]
      }
    }
  }
}

Cron scheduleedit

Defines a schedule using a cron expression that specifiues when to execute a watch.

While cron expressions are powerful, a regularly occurring schedule is easier to configure with the other schedule types. If you must use a cron schedule, make sure you verify it with elasticsearch-croneval .

Configure a cron schedule with one timeedit

To configure a cron schedule, you simply specify the cron expression as a string value. For example, the following snippet configures a cron schedule that triggers every day at noon:

{
  ...
  "trigger" : {
    "schedule" : {
      "cron" : "0 0 12 * * ?"
    }
  }
  ...
}

Configure a cron schedule with multiple timesedit

To configure a cron schedule that triggers multiple times, you can specify an array of cron expressions. For example, the following cron schedule triggers every even minute during weekdays and every uneven minute during the weekend:

{
  ...
  "trigger" : {
    "schedule" : {
      "cron" : [
        "0 0/2 * ? * MON-FRI"",
        "0 1-59/2 * ? * SAT-SUN"
      ]
    }
  }
  ...
}

Use croneval to validate cron expressionsedit

Elasticsearch provides a elasticsearch-croneval command line tool in the $ES_HOME/bin directory that you can use to check that your cron expressions are valid and produce the expected results.

To validate a cron expression, pass it in as a parameter to elasticsearch-croneval:

bin/elasticsearch-croneval "0 0/1 * * * ?"

Interval scheduleedit

A schedule that triggers at a fixed time interval. The interval can be set in seconds, minutes, hours, days, or weeks:

  • "Xs" - trigger every X seconds. For example, "30s" means every 30 seconds.
  • "Xm" - trigger every X minutes. For example, "5m" means every 5 minutes.
  • "Xh" - trigger every X hours. For example, "12h" means every 12 hours.
  • "Xd" - trigger every X days. For example, "3d" means every 3 days.
  • "Xw" - trigger every X weeks. For example, "2w" means every 2 weeks.

If you don’t specify a time unit, it defaults to seconds.

The interval value differs from the standard time value used in Elasticsearch. You cannot configure intervals in milliseconds or nanoseconds.

Configuring an interval scheduleedit

To configure an interval schedule, you specify a string value that represents the interval. If you omit the unit of time (s,m, h, d, or w), it defaults to seconds.

For example, the following interval schedule triggers every five minutes:

{
  "trigger" : {
    "schedule" : {
      "interval" : "5m"
    }
  }
}
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