APIServerSource

An APIServerSource brings Kubernetes API server events into Knative.

Installation

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

Example

This example shows how to create an APIServerSource that listens to Kubernetes Events and send CloudEvents to the Event Display Service.

Creating a namespace

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

kubectl create namespace apiserversource-example

Creating the Event Display Service

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

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

kubectl -n apiserversource-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 a Service Account

Create a Service Account that the ApiServerSource runs as. The ApiServerSource watches for Kubernetes events and forwards them to the Knative Eventing Broker.

kubectl -n apiserversource-example apply -f - << EOF
apiVersion: v1
kind: ServiceAccount
metadata:
 name: events-sa
 namespace: apiserversource-example
---
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
 kind: ClusterRole
 name: event-watcher
subjects:
 - kind: ServiceAccount
   name: events-sa
   namespace: apiserversource-example
EOF

Creating the APIServerSource

In order to receive kubernetes events, you need to create a concrete APIServerSource for the namespace.

• YAML
• kn

kubectl -n apiserversource-example apply -f - << EOF
apiVersion: sources.knative.dev/v1
kind: ApiServerSource
metadata:
 name: testevents
 namespace: apiserversource-example
spec:
 serviceAccountName: events-sa
 mode: Resource
 resources:
   - apiVersion: v1
     kind: Event
 sink:
   ref:
     apiVersion: v1
     kind: Service
     name: event-display
EOF

kn source apiserver create testevents \
  --namespace apiserversource-example \
  --mode "Resource" \
  --resource "Event:v1" \
  --service-account events-sa \
  --sink  --sink http://event-display.svc.cluster.local

Creating Events

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

kubectl -n apiserversource-example run busybox --image=busybox --restart=Never -- ls
kubectl -n apiserversource-example delete pod busybox

Verify

We will verify that the Kubernetes events were sent into the Knative eventing system by looking at our message dumper function logs.

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

You should see log lines similar to:

☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.apiserver.resource.update
  source: https://10.96.0.1:443
  subject: /apis/v1/namespaces/apiserversource-example/events/testevents.15dd3050eb1e6f50
  id: e0447eb7-36b5-443b-9d37-faf4fe5c62f0
  time: 2020-07-28T19:14:54.719501054Z
  datacontenttype: application/json
Extensions,
  kind: Event
  name: busybox.1626008649e617e3
  namespace: apiserversource-example
Data,
  {
    "apiVersion": "v1",
    "count": 1,
    "eventTime": null,
    "firstTimestamp": "2020-07-28T19:14:54Z",
    "involvedObject": {
      "apiVersion": "v1",
      "fieldPath": "spec.containers{busybox}",
      "kind": "Pod",
      "name": "busybox",
      "namespace": "apiserversource-example",
      "resourceVersion": "28987493",
      "uid": "1efb342a-737b-11e9-a6c5-42010a8a00ed"
    },
    "kind": "Event",
    "lastTimestamp": "2020-07-28T19:14:54Z",
    "message": "Started container",
    "metadata": {
      "creationTimestamp": "2020-07-28T19:14:54Z",
      "name": "busybox.1626008649e617e3",
      "namespace": "default",
      "resourceVersion": "506088",
    "selfLink": "/api/v1/namespaces/apiserversource-example/events/busybox.1626008649e617e3",
      "uid": "2005af47-737b-11e9-a6c5-42010a8a00ed"
    },
    "reason": "Started",
    "reportingComponent": "",
    "reportingInstance": "",
    "source": {
      "component": "kubelet",
      "host": "gke-knative-auto-cluster-default-pool-23c23c4f-xdj0"
    },
    "type": "Normal"
  }

Cleanup

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

kubectl delete namespace apiserversource-example

Reference Documentation

See the APIServerSource specification.

Contact

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

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