Timer Triggers

Invoke functions on a cron schedule with timer triggers using fission timer create, supporting cron specs and descriptors like @every.

A time trigger invokes a function on a cron schedule — once, or repeatedly. Use it for periodic jobs such as cleanups, report generation, or polling an external system.

The timer component evaluates your schedule using server time and POSTs to your function through the router when each scheduled moment arrives.

Cron format

Schedules are written as robfig/cron specifications. Fission accepts the standard five fields and an optional leading seconds field, so a spec is either:

┌───────────── second (optional, 0 - 59)
│ ┌───────────── minute (0 - 59)
│ │ ┌───────────── hour (0 - 23)
│ │ │ ┌───────────── day of month (1 - 31)
│ │ │ │ ┌───────────── month (1 - 12)
│ │ │ │ │ ┌───────────── day of week (0 - 6)
│ │ │ │ │ │
* * * * * *

Friendlier descriptors such as @every 1m, @hourly, and @daily are also supported.

Create a time trigger

Run a function every 30 minutes:

$ fission timer create --name halfhourly --function hello --cron "0 */30 * * * *"
trigger 'halfhourly' created
Current Server Time: 2019-12-17T08:33:28Z
Next 1 invocation: 2019-12-17T09:00:00Z

Or use a descriptor instead of a cron field list:

$ fission timer create --name minute --function hello --cron "@every 1m"
trigger 'minute' created
Current Server Time: 2019-12-17T08:33:43Z
Next 1 invocation: 2019-12-17T08:34:43Z

List time triggers

List your triggers to see their function and cron spec:

$ fission timer list
NAME       CRON           FUNCTION_NAME
halfhourly 0 */30 * * * * hello
minute     @every 1m      hello

Test a schedule

Use showschedule to preview the upcoming invocations for a cron spec without creating a trigger. This is the quickest way to check that a spec means what you think it does.

$ fission timer showschedule --cron "0 30 * * * *" --round 5
Current Server Time: 2018-06-12T05:07:41Z
Next 1 invocation: 2018-06-12T05:30:00Z
Next 2 invocation: 2018-06-12T06:30:00Z
Next 3 invocation: 2018-06-12T07:30:00Z
Next 4 invocation: 2018-06-12T08:30:00Z
Next 5 invocation: 2018-06-12T09:30:00Z
Schedules are evaluated against the server’s time, not your laptop’s. The times printed above come from the Fission cluster.
Last modified June 6, 2026: SEO + LLM-friendliness: JSON-LD, llms.txt, descriptions, robots, titles (#289) (6cead82)