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Yandex Cloud Functions

Timer

Timer is a trigger that runs a function on a schedule. The schedule is entered as a cron expression. The cron expression uses Coordinated Universal Time (UTC).

Cron expression format

The order of fields in the cron expression: Minutes Hours Day-of-month Month Day-of-week Year.

Possible field values

Note

Special characters used, as well as the names of months and days of the week, are case-insensitive: MON is equivalent to mon.

Field
name.		 Required
field		 Acceptable
values		 Special
characters
supported
Minutes Yes 0-59 ,, -, *, /
Hours Yes 0-23 ,, -, *, /
Day of month Yes 1-31 ,, -, *, ?, /, L, W
Month Yes 1-12,
JAN-DEC		 ,, -, *, /
Day of week Yes 1-7,
SUN-SAT		 ,, -, *, ?, /, L, #
Year No empty, 1970-2099 ,, -, *, /

Special characters

You can use the following special characters in the cron expressions:

  • * — Select all values in the field.

    The * character in the Minutes field: the trigger starts every minute.

  • ? — Select any field value. You cannot fill Day of month and Day of week at the same time. If you entered a value in one of these fields, enter ? in the other field.

    10 in Day of month and ? in Day of week: the trigger is launched every 10th day of the month.

  • `` — Select a range of values.

    The 10-12 range in Hours: the trigger runs at 10 a.m., 11 a.m., and at noon.

  • , — Select multiple values.

    MON, WED, FRI in the Day of week field: The trigger runs on Monday, Wednesday, and Friday.

  • / — Increment the value.

    0/15 in the Minutes field: The trigger starts at 0, 15, 30, and 45 minutes past each hour.

  • L — This character functions differently in the two fields where it's used:

    • In the Day of month field, it means the last day of the month.
    • In the Day of week field, it means the last day of the week, 7 (Saturday, SAT).

    L in the Day of month field: The trigger runs on January 31, February 28, and so on.

  • W — Select the weekday nearest to the specified date.

    15W in the Day of month field: The trigger is run on the weekday nearest to the 15th day of the month. If the 15th day is Saturday, the trigger runs on Friday the 14th.

    Note

    The characters L and W in the Day of month field can be also merged into LW: The trigger is run on the last weekday of the month.

  • # — Select the Nth day of the month.

    The value 6#3 in the Day of week field: The trigger runs on the third Friday of the month (6 — Friday, 3 — the third Friday of the month).

Examples of cron expressions

Cron expression Description
* * * * ? * The trigger is run every minute.
0 * ? * * * The trigger is run every hour.
15 10 ? * * * The trigger is run every day at 10:15 a.m.

Roles required for the timer to run correctly

  • To create a timer, you need a permission for the service account that runs the timer executing the operation. This permission is included in the roles iam.serviceAccounts.user, editor, and higher.
  • To run a timer, the service account needs the serverless.functions.invoker role for the folder containing the function called by the timer.

Learn more about access management.

Timer message format

After the trigger is activated, it sends the following message to the function:

{
  "messages": [
    {
      "event_metadata": {
        "event_id": "a1s41g2n5g0o5p778k4r",
        "event_type": "yandex.cloud.events.serverless.triggers.TimerMessage",
        "created_at": "2019-12-04T12:05:14.227761Z",
        "cloud_id": "b1gvlrnlei4l5idm9cbj",
        "folder_id": "b1g88tflru0ek1omtsu0"
      },
      "details": {
        "trigger_id": "a1sfe084v4se4morbu2i"
      }
    }
  ]
}
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