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Cron expression reference - Distributed Load Testing on AWS
Accepted valuesUnsupported patternsPreset patternsScheduling constraints

Cron expression reference

This solution uses a subset of the standard 5-field Linux cron format for recurring test schedules. The cron expression consists of five fields separated by spaces.

┌───────── minute (0-59)
│ ┌─────── hour (0-23, *, */N, or comma list)
│ │ ┌───── day of month (1-31 or *)
│ │ │ ┌─── month (1-12 or *)
│ │ │ │ ┌─ day of week (0-6, *, range, or list)
│ │ │ │ │
0 9 * * 1-5

Accepted values

The following table describes what each field accepts.

Field Accepted values Examples

Minute

A single value from 0 to 59.

0, 30, 45

Hour

(every hour), a step value , a single value from 0 to 23, or a comma-separated list of values.

, , 9, 9,17

Day of month

* (every day) or a single value from 1 to 31.

*, 1, 15, 31

Month

* (every month) or a single value from 1 to 12.

*, 1, 6, 12

Day of week

* (every day), a single value from 0 to 6, a range using a hyphen, or a comma-separated list.

*, 0, 1-5, 0,6

Day of week values use the following mapping: 0 = Sunday, 1 = Monday, 2 = Tuesday, 3 = Wednesday, 4 = Thursday, 5 = Friday, 6 = Saturday.

Unsupported patterns

The following patterns are valid Linux cron syntax but are not supported by this solution.

Pattern Example Reason

Minute step values

*/15 * * * *

The minimum scheduling interval is one hour.

Minute lists

0,30 * * * *

The minimum scheduling interval is one hour.

Day of month ranges

0 9 1-15 * *

Only a single day value or wildcard is accepted.

Day of month lists

0 9 1,15 * *

Only a single day value or wildcard is accepted.

Month ranges

0 9 * 3-9 *

Only a single month value or wildcard is accepted.

Month lists

0 9 1 1,6,12 *

Only a single month value or wildcard is accepted.

Question mark

0 9 ? * ?

The question mark character is not valid in standard Linux cron. Use * instead.

Preset patterns

The web console provides the following preset patterns that you can select with a single click.

Pattern name Expression Description

Every hour

0 * * * *

Runs at minute 0 of every hour.

Daily at 9:00 AM

0 9 * * *

Runs once daily at 9:00 AM in the selected timezone.

Weekdays at 8:00 AM

0 8 * * 1-5

Runs Monday through Friday at 8:00 AM.

Every Sunday at 5 PM

0 17 * * 0

Runs every Sunday at 5:00 PM.

1st of month at 11 AM

0 11 1 * *

Runs on the first day of every month at 11:00 AM.

Scheduling constraints

  • The minimum interval between scheduled test runs is one hour. The system validates that the interval between consecutive runs is longer than the estimated test duration.

  • An expiry date is required for all recurring schedules. Tests will not run after the end of the expiry date (UTC).

  • The schedule timezone determines when the cron fires. Daylight Saving Time transitions are handled automatically. If a scheduled time does not exist due to a DST spring-forward transition, that occurrence is skipped.

  • The system validates the cron expression on both the web console and the API. If the expression does not match the accepted format, the test cannot be created.