PingSource

A PingSource produces events with a fixed payload on a specified cron schedule.

Installation

The PingSource source type is enabled by default when you install Knative Eventing.

Example

This example shows how to send an event every minute to a Event Display Service.

Creating a namespace

Create a new namespace called pingsource-example by entering the following command:

kubectl create namespace pingsource-example

Creating the Event Display Service

In this step, you create one event consumer, event-display to verify that PingSource is properly working.

To deploy the event-display consumer to your cluster, run the following command:

kubectl -n pingsource-example apply -f - << EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: event-display
spec:
  replicas: 1
  selector:
    matchLabels: &labels
      app: event-display
  template:
    metadata:
      labels: *labels
    spec:
      containers:
        - name: event-display
          image: gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display

---

kind: Service
apiVersion: v1
metadata:
  name: event-display
spec:
  selector:
    app: event-display
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080
EOF

Creating the PingSource

You can now create the PingSource sending an event containing {"message": "Hello world!"} every minute.

YAML

kubectl create -n pingsource-example -f - <<EOF
apiVersion: sources.knative.dev/v1beta2
kind: PingSource
metadata:
  name: test-ping-source
spec:
  schedule: "*/1 * * * *"
  contentType: "application/json"
  data: '{"message": "Hello world!"}'
  sink:
    ref:
      apiVersion: v1
      kind: Service
      name: event-display
EOF

Kn

kn source ping create test-ping-source \
  --namespace pingsource-example \
  --schedule "*/1 * * * *" \
  --data '{"message": "Hello world!"}' \
  --sink http://event-display.pingsource-example.svc.cluster.local

Warning

Notice that the namespace is specified in two places in the command in --namespace and the --sink hostname

(Optional) Create a PingSource with binary data

Sometimes you may want to send binary data, which cannot be directly serialized in yaml, to downstream. This can be achieved by using dataBase64 as the payload. As the name suggests, dataBase64 should carry data that is base64 encoded.

Please note that data and dataBase64 cannot co-exist.

cat <<EOF | kubectl create -f -
apiVersion: sources.knative.dev/v1beta2
kind: PingSource
metadata:
  name: test-ping-source-binary
spec:
  schedule: "*/2 * * * *"
  contentType: "text/plain"
  dataBase64: "ZGF0YQ=="
  sink:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: event-display
EOF

Verify

View the logs for the event-display event consumer by entering the following command:

kubectl -n pingsource-example logs -l app=event-display --tail=100

This returns the Attributes and Data of the events that the PingSource sent to the event-display Service:

☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.sources.ping
  source: /apis/v1/namespaces/default/pingsources/test-ping-source
  id: d8e761eb-30c7-49a3-a421-cd5895239f2d
  time: 2019-12-04T14:24:00.000702251Z
  datacontenttype: application/json
Data,
  {
    "message": "Hello world!"
  }

If you created a PingSource with binary data, you should also see the following:

☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.sources.ping
  source: /apis/v1/namespaces/default/pingsources/test-ping-source-binary
  id: a195be33-ff65-49af-9045-0e0711d05e94
  time: 2020-11-17T19:48:00.48334181Z
  datacontenttype: text/plain
Data,
  ZGF0YQ==

Cleanup

Delete the pingsource-example namespace and all of its resources from your cluster by entering the following command:

kubectl delete namespace pingsource-example

Reference Documentation

See the PingSource specification.

Contact

For any inquiries about this source, please reach out on to the Knative users group.