Cron Expression Basics¶
DataKitchen's DataOps Automation uses the Kubernetes scheduler for order scheduling.
The system translates standard cron syntax and time zone definitions to set the date/time for scheduled order runs.
Cron fields¶
Automation cron expressions are strings of five fields separated by spaces: <minute> <hour> <day-of-month> <month> <day-of-week>
Where:
- minute = 0-59
- hour = 0-23
- day-of-month = 1-31
- month = 1-12 or JAN-DEC
- day-of-week = 0-7 or SUN-SAT (Sunday can be represented by either 0 or 7 or SUN)
Considerations¶
- Multiple days can be listed as strings or numerals, as in MON,WED,THU or 1,3,4 and MON-THU or 1-4.
- String literals are case-insensitive, so THU, thu, and Thu are all valid syntax for Thursday.
- Automation does not support the
secondandyearfields found in some cron implementations.
Cron characters¶
| Character | Use |
|---|---|
| Asterisk (*) | Means "all," as in the order should run for every unit of time where the asterisk appears in the expression. |
| Dash (-) | Means "range," as in a range of units of time. For example, "1-4" in the day-of-week field sets the schedule for Monday through Thursday. NOTE: commas and dashes cannot be used together for non-UTC time zones. Dashes are not supported in day-of-month or day-of-week fields if there is hour overflow |
| Comma (,) | Separates multiple values in a unit of time. For example, "MON, WED, FRI" in the day-of-week field sets the schedule to run on those three days. NOTE: commas and dashes cannot be used together for non-UTC time zones. |
| Forward slash (/) | Defines the starting value and incremental or step value in a unit of time. For example, "5/15" in the minute field sets the schedule to run at the 5, 20, 35, and 50 minute marks of an hour. |
Warning
Characters fail with non-UTC time zones. At this time, the DataOps Automation cron scheduler does not support the use of commas and dashes together when schedules are set using non-UTC time zones. Use the UTC time zone with complex schedules, as in "2,5,15-45/2 2 1-5,7,31 MAR,DEC WED".
Time zones¶
While the Automation scheduler supports many time zones, due to the translations the system must perform, there are limitations when using certain cron syntax with non-UTC time zones.
Schedules with non-UTC time zones cannot include cron expressions with both commas and dashes.
UTC workaround¶
As a workaround, select UTC for the Time Zone, then write a cron expression with the appropriate hours pre-translated.
Visual example in Automation¶
Examples of supported cron expressions¶
The syntax follows this field order: <minute> <hour> <day-of-month> <month> <day-of-week>
Tip
See crontab.guru for additional help in translating cron expressions.
| Expression | Definition |
|---|---|
0 15 * * * |
At 3:00 pm every day |
30 9 * * MON-FRI 30 9 * * 1-5 |
Both run at 9:30 am every Mon, Tue, Wed, Thurs, and Fri |
15,45 7 * 4 TUE |
At 7:15 am and 7:45 am every Tuesday in April |
0 6,18 15 * * |
At 6:00 am and 6:00 pm on the 15th day of every month |
0 0 10/5 * * |
At 00:00 on every 5th day-of-month from 10 through 31 |
Examples with UTC¶
| Standard time zone expression | UTC time zone expression |
|---|---|
30 09 * * * At 9:30 am every day, EST (America/New_York, UTC-05:00) |
30 14 * * * At 14:30 every day, UTC |
15,45 22 * * TUE At 10:15 pm and 10:45 pm every Tue, EST (America/New_York, UTC-05:00) |
15,45 3 * * WED At 03:15 and 03:45 every Wed, UTC (UTC translation shifts to the next day) |