Script filter¶

Script filters can be used to filter the events with LUA scripts.

Script filters are applied to the event data. A CloudEvent from Webhook event-source has payload structure as:

{
  "context": {
    "type": "type_of_event_source",
    "specversion": "cloud_events_version",
    "source": "name_of_the_event_source",
    "id": "unique_event_id",
    "time": "event_time",
    "datacontenttype": "type_of_data",
    "subject": "name_of_the_configuration_within_event_source"
  },
  "data": {
    "header": {},
    "body": {}
  }
}

Fields¶

An Script filter can be defined under filters with a field script:

filters:
  script: |-
    if event.body.a == "b" and event.body.d.e == "z" then return true else return false end

Practical example¶

Create a webhook event-source

kubectl -n argo-events apply -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/event-sources/webhook.yaml

Create a webhook sensor with context filter

kubectl -n argo-events apply -f https://raw.githubusercontent.com/argoproj/argo-events/stable/examples/sensors/filter-script.yaml

Send an HTTP request to the event-source

kubectl port-forward svc/webhook-eventsource-svc 12000
curl -d '{"hello": "world"}' -X POST http://localhost:12000/example

You will notice in sensor logs that the event did not trigger anything.

Send another HTTP request the event-source

curl -X POST -d '{"a": "b", "d": {"e": "z"}}' http://localhost:12000/example

Then you will see the event successfully triggered a workflow creation.