Scheduled Tasks
This page documents Generation 1, which has reached End of Life. Gen 1 apps use
docker-compose.yml. For current documentation, see Timers.
Convox can set up cron-like recurring tasks on any of your application processes. This can be useful for background work like data dumps, batch jobs, or even queueing other background jobs for a worker.
Configuring tasks
Scheduled tasks are configured in docker-compose.yml using labels in the convox.cron namespace. The label format is:
convox.cron.<task name>=<cron expression> <command>
-
task name is a unique name for each task that you choose. Task names may not be reused within the same application process. A name starts with a letter, contains only letters, digits and dashes, and is 4 to 30 characters long.
-
cron expression describes the schedule on which the task will be invoked. See "Cron expression format" below for more info.
-
command is the command to be run in this process. Before configuring the task you can test that your command works by running
convox run <process name> <command>.
Example: to run the command bin/myjob every hour on the web process, you would configure the label like this:
web:
labels:
- convox.cron.myjob=0 * * * ? bin/myjob
Cron expression format
Cron expressions use the following format. All times are UTC.
.----------------- minute (0 - 59)
| .-------------- hour (0 - 23)
| | .----------- day-of-month (1 - 31)
| | | .-------- month (1 - 12) OR JAN,FEB,MAR,APR ...
| | | | .----- day-of-week (1 - 7) OR SUN,MON,TUE,WED,THU,FRI,SAT
| | | | |
* * * * *
Note: One of the day-of-month and day-of-week fields must be
?. An expression cannot set both.Each run starts after a random delay of up to 10 seconds, so jobs scheduled for the same minute can start in any order. To run jobs in a specific order, schedule them in different minutes.
Some example expressions:
| Expression | Meaning |
|---|---|
* * * * ? |
Run every minute |
*/10 * * * ? |
Run every 10 minutes |
0 * * * ? |
Run every hour |
30 6 * * ? |
Run at 6:30am UTC every day |
30 18 ? * MON-FRI |
Run at 6:30pm UTC every weekday |
0 12 1 * ? |
Run at noon on the first day of every month |
0 0,12 * * ? |
Run at Midnight and Noon every day |
See the Scheduled Events AWS documentation for more details.
Run options and persistence
The service a scheduled task is associated with does not necessarily need running containers all the time. The service can be scaled down to -1 or 0, and the scheduled task will "wake it up," causing a container to be created for the scheduled to task to run in, and exiting when it finishes.
See Also
