Triggers

Tools

For documentation purposes it is assumed the reader has flowctl installed. To see how, please see the repo README. For more information on the trigger commands, see the trigger command documentation in flowctl.

Flowdat workflows can be triggered according to custom criteria with the Flowdapt trigger service. A trigger resource is defined in its own yaml file and follows the same general kubernetes schema as workflows and configs:

kind: trigger_rule
metadata:
  name: trigger_fallback_on_fail
spec:
  type: condition
  rule:
    and:
      - eq:
        - var: type
        - com.event.workflow.workflow_finished
      - eq:
        - var: data.workflow
        - test_simple
      - eq:
        - var: data.state
        - failed
  action:
    target: run_workflow
    parameters:
      workflow: fallback_workflow

We see how the above condition is defined as a list of three criteria that all must be satisifed (eq) in order to trigger the action. The type of event must be a workflow_finished type, the data.workflow of the workflow must be test_simple, and the data.state of the workflow must be failed.

Once all three of these criteria are met, the trigger service will automatically launch another workflow with the name fallback_workflow (which must exist in the database by a previous flowctl apply -p path/to/workflow.yaml details here)

Add the trigger

The example above can be saved into a file called fallback_trigger.yaml and then it can be added to the Flowdapt server by running:

flowctl apply -p /path/to/fallback_trigger.yaml`

After it is added, the Flowdapt service will automatically begin monitoring for this event and then triggering the fallback_workflow whenever the three criteria are met.

Setting a schedule trigger

The workflow can also be scheduled to periodically re-run itself using the schedule key. This type of workflow is good for any workflow that the user knows they want to run on a set frequency such as model retraining, or fetching/updating data at constant intervals in time. Flowdapt adopts the standard crontab syntax for setting the schedule which follows:

kind: trigger_rule
metadata:
  name: create_features
spec:
  type: schedule
  rule:
    - "*/5 * * * *"
  action:
    target: run_workflow
    parameters:
      workflow: create_features

Here the schedule is set to "*/5 * * * *" which indicates the min, hour, dom, mon, dow where min is the minute, hour is the hour, dom is the day of the month, mon is the month, and dow is the day of the week (0-6). An asterisk, as used for all entries in the prior example, indicates all times. So the example workflow above will be executed for each minute of each hour of all days of all months. If a user wants to instead run their workflow every 15 minutes, only on Mondays, they could set their schedule as "*/15 * * * 1". More details about crontab settings can be found here

As with all other flowdapt resources, the schedule trigger can be added to the server with:

flowctl apply -p /path/to/schedule_trigger.yaml

Once it is applied, the schedule becomes activated. The schedule can be removed by deleting the trigger with flowctl delete -p path/to/schedule_trigger.