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Cron schedule

Run a Flow on a recurring schedule without inventing a scheduler service.

Problem and approach​

Demonstrates starting a Dex flow with a cron schedule so each tick runs the flow like a recurring job.

Key components​

  1. CronScheduleStarter — on Spring ApplicationReadyEvent, starts flow ID cron-schedule-sample with cron expression */1 * * * * (idempotent if already started).
  2. CronScheduleFlow — the scheduled flow; each trigger runs its start step and completes.

How it starts​

CronScheduleStarter uses the shared Dex Client after the Worker is up:

client.startFlow(
    cronScheduleFlow,
    "cron-schedule-sample",
    null,
    StartFlowOptions.newBuilder()
        .timeout(Duration.ofHours(1))
        .cronSchedule("*/1 * * * *")
        .build());

If the flow is already running, FLOW_ALREADY_STARTED is ignored so restarts are safe.

Schedule management​

View and manage the underlying Temporal schedule in the Temporal UI (local dexcli Temporal or Temporal Cloud):

  • Flows — filter by Flow ID cron-schedule-sample
  • Schedules — pause, trigger, or delete

To change the schedule: update CronScheduleStarter, deploy, delete the old schedule in the UI if needed, then restart the sample process so it recreates the schedule.

Current limitations​

Schedule overlap policy is not exposed and defaults to skip overlapping runs.

Code examples​

Full runnable samples live under examples/{go,java,python,typescript} (HTTP prefix /design-pattern/... where applicable).

# See examples/python/dex_examples/patterns/workflow/cron/