Creating an ApiServerSource object

Creating an ApiServerSource object

This topic describes how to create an ApiServerSource object.

Before you begin

Before you can create an ApiServerSource object:

You must have Knative Eventing installed on your cluster.
You must install the kubectl CLI tool.
Optional: If you want to use the kn commands, install the kn tool.

Create an ApiServerSource object

Optional: Create a namespace for the API server source instance by running the command:
```
kubectl create namespace <namespace>
```
Where <namespace> is the name of the namespace that you want to create.

Note

Creating a namespace for your ApiServerSource and related components allows you to view changes and events for this workflow more easily, because these are isolated from the other components that might exist in your default namespace.

It also makes removing the source easier, because you can delete the namespace to remove all of the resources.
Create a ServiceAccount:
1. Create a YAML file using the following template:
```
apiVersion: v1
kind: ServiceAccount
metadata:
  name: <service-account>
  namespace: <namespace>
```
  Where:
  - <service-account> is the name of the ServiceAccount that you want to create.
  - <namespace> is the namespace that you created in step 1 earlier.
2. Apply the YAML file by running the command:
```
kubectl apply -f <filename>.yaml
```
  Where <filename> is the name of the file you created in the previous step.
Create a Role:
1. Create a YAML file using the following template:
```
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: <role>
rules:
  <rules>
```
  Where:
  - <role> is the name of the Role that you want to create.
  - <rules> are the set of permissions you want to grant to the APIServerSource object. This set of permissions must match the resources you want to receive events from. For example, to receive events related to the events resource, use the following set of permissions:
```
- apiGroups:
  - ""
  resources:
  - events
  verbs:
  - get
  - list
  - watch
```
    Note
    
    The only required verbs are get, list and watch.
2. Apply the YAML file by running the command:
```
kubectl apply -f <filename>.yaml
```
  Where <filename> is the name of the file you created in the previous step.
Create a RoleBinding:
1. Create a YAML file using the following template:
```
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: <role-binding>
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: <role>
subjects:
- kind: ServiceAccount
  name: <service-account>
  namespace: <namespace>
```
  Where:
  - <role-binding> is the name of the RoleBinding that you want to create.
  - <role> is the name of the Role that you created in step 3 earlier.
  - <service-account> is the name of the ServiceAccount that you created in step 2 earlier.
  - <namespace> is the name of the namespace that you created in step 1 earlier.
2. Apply the YAML file by running the command:
```
kubectl apply -f <filename>.yaml
```
  Where <filename> is the name of the file you created in the previous step.

Create a sink. If you do not have your own sink, you can use the following example Service that dumps incoming messages to a log:

Copy the YAML below into a file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: event-display
  namespace: <namespace>
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/cmd/event_display
---
kind: Service
apiVersion: v1
metadata:
  name: event-display
  namespace: <namespace>
spec:
  selector:
    app: event-display
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080

Where <namespace> is the name of the namespace that you created in step 1 above.

Apply the YAML file by running the command:
```
kubectl apply -f <filename>.yaml
```
Where <filename> is the name of the file you created in the previous step.

Create the ApiServerSource object:

kn
- To create the ApiServerSource, run the command:
```
kn source apiserver create <apiserversource> \
  --namespace <namespace> \
  --mode "Resource" \
  --resource "Event:v1" \
  --service-account <service-account> \
  --sink <sink-name>
```
  Where:
  - <apiserversource> is the name of the source that you want to create.
  - <namespace> is the name of the namespace that you created in step 1 earlier.
  - <service-account> is the name of the ServiceAccount that you created in step 2 earlier.
  - <sink-name> is the name of your sink, for example, http://event-display.pingsource-example.svc.cluster.local.
  For a list of available options, see the Knative client documentation.
YAML
1. Create a YAML file using the following template:
```
apiVersion: sources.knative.dev/v1
kind: ApiServerSource
metadata:
 name: <apiserversource-name>
 namespace: <namespace>
spec:
 serviceAccountName: <service-account>
 mode: <event-mode>
 resources:
   - apiVersion: v1
     kind: Event
 sink:
   ref:
     apiVersion: v1
     kind: <sink-kind>
     name: <sink-name>
```
  Where:
  - <apiserversource-name> is the name of the source that you want to create.
  - <namespace> is the name of the namespace that you created in step 1 earlier.
  - <service-account> is the name of the ServiceAccount that you created in step 2 earlier.
  - <event-mode> is either Resource or Reference. If set to Resource, the event payload contains the entire resource that the event is for. If set to Reference, the event payload only contains a reference to the resource that the event is for. The default is Reference.
  - <sink-kind> is any supported Addressable object that you want to use as a sink, for example, Service or Deployment.
  - <sink-name> is the name of your sink.
  For more information about the fields you can configure for the ApiServerSource object, see ApiServerSource reference.
2. Apply the YAML file by running the command:
```
kubectl apply -f <filename>.yaml
```
  Where <filename> is the name of the file you created in the previous step.

Verify the ApiServerSource object

Make the Kubernetes API server create events by launching a test Pod in your namespace by running the command:
```
kubectl run busybox --image=busybox --namespace=<namespace> --restart=Never -- ls
```
Where <namespace> is the name of the namespace that you created in step 1 earlier.
Delete the test Pod by running the command:
```
kubectl --namespace=<namespace> delete pod busybox
```
Where <namespace> is the name of the namespace that you created in step 1 earlier.

View the logs to verify that Kubernetes events were sent to the sink by the Knative Eventing system by running the command:

kubectl logs --namespace=<namespace> -l app=<sink> --tail=100

Where:

<namespace> is the name of the namespace that you created in step 1 earlier.
<sink> is the name of the PodSpecable object that you used as a sink in step 5 earlier.

Example log output:

☁️  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"
  }

Delete the ApiServerSource object

To remove the ApiServerSource object and all of the related resources:

Delete the namespace by running the command:
```
kubectl delete namespace <namespace>
```
Where <namespace> is the name of the namespace that you created in step 1 earlier.