Kubernetes event using the API Server Source

1. You must have a Knative cluster running both the Serving and Eventing components. To learn how to install the required components, see Installing Knative.

2. You can follow the steps below to create new files, or you clone a copy from the repo by running:

These instructions assume the namespace , which you can change to your preferred namespace. If you use a different namespace, you will need to modify all the YAML files deployed in this sample to point at that namespace.

1. Create the default Broker in your namespace:

   kubectl create -f - <<EOF
   apiVersion: eventing.knative.dev/v1
   kind: Broker
   metadata:
    name: default
   EOF

Service Account

1. Create a Service Account that the ApiServerSource runs as. The ApiServerSource watches for Kubernetes events and forwards them to the Knative Eventing Broker. Create a file named serviceaccount.yaml and copy the code block below into it.

   apiVersion: v1
   kind: ServiceAccount
   metadata:
     name: events-sa
     namespace: default
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRole
   metadata:
     name: event-watcher
   rules:
     - apiGroups:
         - ""
       resources:
         - events
       verbs:
         - get
         - list
         - watch
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: k8s-ra-event-watcher
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     name: event-watcher
   subjects:
     - kind: ServiceAccount
       name: events-sa
       namespace: default

   If you want to re-use an existing Service Account with the appropriate permissions, you need to modify the serviceaccount.yaml.

2. kubectl apply --filename serviceaccount.yaml

1. In order to receive events, you have to create a concrete Event Source for a specific namespace. Create a file named k8s-events.yaml and copy the code block below into it.

   If you want to consume events from a different namespace or use a different Service Account, you need to modify k8s-events.yaml accordingly.

2. Enter the following command to create the event source:

Trigger

In order to check the ApiServerSource is fully working, we will create a simple Knative Service that dumps incoming messages to its log and creates a Trigger from the Broker to that Knative Service.

1. Create a file named trigger.yaml and copy the code block below into it.

   apiVersion: eventing.knative.dev/v1
   kind: Trigger
   metadata:
     name: testevents-trigger
     namespace: default
   spec:
     broker: default
     subscriber:
       ref:
         apiVersion: serving.knative.dev/v1
         kind: Service
         name: event-display
   ---
   # This is a very simple Knative Service that writes the input request to its log.
   apiVersion: serving.knative.dev/v1
   kind: Service
   metadata:
     name: event-display
     namespace: default
   spec:
     template:
       spec:
         containers:
           - # This corresponds to
             # https://github.com/knative/eventing-contrib/tree/master/cmd/event_display/main.go
             image: gcr.io/knative-releases/knative.dev/eventing-contrib/cmd/event_display

2. If the deployed ApiServerSource is pointing at a Broker other than default, modify trigger.yaml by adding spec.broker with the Broker‘s name.

3. kubectl apply --filename trigger.yaml

Create events by launching a pod in the default namespace. Create a busybox container and immediately delete it:

Verify

We will verify that the Kubernetes events were sent into the Knative eventing system by looking at our message dumper function logs. If you deployed the Trigger, continue using this section. If not, you will need to look downstream yourself:

kubectl get pods
kubectl logs -l serving.knative.dev/service=event-display -c user-container

You should see log lines similar to:

☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  source: https://10.96.0.1:443
  subject: /apis/v1/namespaces/default/events/testevents.15dd3050eb1e6f50
  time: 2020-07-28T16:35:14.172979816Z
  datacontenttype: application/json
Extensions,
  kind: Event
  knativearrivaltime: 2020-07-28T16:35:14.173381505Z
  knativehistory: default-kne-trigger-kn-channel.default.svc.cluster.local
  name: busybox.1625f7cfa4cd12f8
  namespace: default
Data,
  {
    "apiVersion": "v1",
    "count": 1,
    "eventTime": null,
    "firstTimestamp": "2020-07-28T16:35:14Z",
    "involvedObject": {
      "apiVersion": "v1",
      "fieldPath": "spec.containers{busybox}",
      "kind": "Pod",
      "name": "busybox",
      "namespace": "default",
      "resourceVersion": "28987493",
      "uid": "1efb342a-737b-11e9-a6c5-42010a8a00ed"
    },
    "kind": "Event",
    "lastTimestamp": "2020-07-28T16:35:14Z",
    "message": "Started container",
    "metadata": {
      "creationTimestamp": "2020-07-28T16:35:14Z",
      "name": "busybox.1625f7cfa4cd12f8",
      "namespace": "default",
      "resourceVersion": "506088",
      "selfLink": "/api/v1/namespaces/default/events/busybox.1625f7cfa4cd12f8",
      "uid": "7f841049-7979-48db-9cbc-93ed2346a1b5",
    },
    "reason": "Started",
    "reportingComponent": "",
    "reportingInstance": "",
    "source": {
      "component": "kubelet",
      "host": "gke-knative-auto-cluster-default-pool-23c23c4f-xdj0"
    },
    "type": "Normal"
  }

You can remove the ServiceAccount, ClusterRoles, ClusterRoleBinding, ApiServerSource, Service and Trigger using:

kubectl --namespace default delete --filename serviceaccount.yaml

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