PingSource example

This example shows how to configure PingSource as an event source targeting a Knative Service.

Before you begin

  1. Set up Knative Serving.
  2. Set up Knative Eventing.

Create a Knative Service

To verify that PingSource is working, create a simple Knative Service that dumps incoming messages to its log.

Use following command to create the service from STDIN:

cat <<EOF | kubectl create -f -
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: event-display
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display
EOF

Use following command to create the service using the kn cli:

kn service create event-display --image gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display

Create a PingSource

For each set of ping events that you want to request, create an Event Source in the same namespace as the destination.

Use following command to create the event source from STDIN:

cat <<EOF | kubectl create -f -
apiVersion: sources.knative.dev/v1beta2
kind: PingSource
metadata:
  name: test-ping-source
spec:
  schedule: "*/2 * * * *"
  contentType: "application/json"
  data: '{"message": "Hello world!"}'
  sink:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: event-display
EOF

Use following command to create the event source from the ping-source.yaml file:

kn source ping create test-ping-source \
  --schedule "*/2 * * * *" --data \
  '{ "message": "Hello world!" }' \
  --sink ksvc:event-display

(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.

Use the following command to create the event source with binary data from STDIN:

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

Verify that the message was sent to the Knative eventing system by looking at message dumper logs.

Use following command to view the logs of the event-display service:

kubectl logs -l serving.knative.dev/service=event-display -c user-container --since=10m

You can also use kail instead of kubectl logs to tail the logs of the subscriber.

kail -l serving.knative.dev/service=event-display -c user-container --since=10m

You should see log lines showing the request headers and body from the source:

☁️  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

You can delete the PingSource instance by entering the following command:

kubectl delete pingsources.sources.knative.dev test-ping-source
kubectl delete pingsources.sources.knative.dev test-ping-source-binary

kn source ping delete test-ping-source
kn source ping delete test-ping-source-binary

Similarly, you can delete the Service instance via:

kubectl delete service.serving.knative.dev event-display

kn service delete event-display