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Kafka Trigger

Kafka trigger allows sensor to publish events on Kafka topic. This trigger helps source the events from outside world into your messaging queues.

Specification

The Kafka trigger specification is available here.

Walkthrough

  1. Consider a scenario where you are expecting a file drop onto a Minio bucket and want to place that event on a Kafka topic.

  2. Set up the Minio Event Source here. Do not create the Minio sensor, we are going to create it in next step.

  3. Lets create the sensor.

    apiVersion: argoproj.io/v1alpha1
    kind: Sensor
    metadata:
      name: minio-sensor
    spec:
      dependencies:
        - name: test-dep
          eventSourceName: minio
          eventName: example
      triggers:
        - template:
            name: kafka-trigger
            kafka:
              # Kafka URL
              url: kafka.argo-events.svc:9092
              # Name of the topic
              topic: minio-events
              # partition id
              partition: 0
              payload:
                - src:
                    dependencyName: test-dep
                    dataKey: notification.0.s3.object.key
                  dest: fileName
                - src:
                    dependencyName: test-dep
                    dataKey: notification.0.s3.bucket.name
                  dest: bucket
    
  4. The Kafka message needs a body. In order to construct message based on the event data, sensor offers payload field as a part of the Kafka trigger.

The payload contains the list of src which refers to the source event and dest which refers to destination key within result request payload.

The payload declared above will generate a message body like below.

    {
        "fileName": "hello.txt" // name/key of the object
        "bucket": "input" // name of the bucket
    }
  1. Drop a file called hello.txt onto the bucket input and you will receive the message on Kafka topic