Getting started

Getting started

Prerequisites

Before you can create an API server source, you must install Knative Eventing and the kubectl CLI tool.

Create an API server source

Optional: Create a namespace for the API server source instance:
```
kubectl create namespace <namespace>
```
where;
- <namespace> is the name of the namespace that you want to create.
Creating a namespace for your API server source and related components allows you to view changes and events for this workflow more easily, since these are isolated from the many other components that may exist in your default namespace.

It also makes removing the source easier, since you can simply delete the namespace to remove all of the resources.
Create a service account:
```
kubectl create -f - <<EOF
apiVersion: v1
kind: ServiceAccount
metadata:
  name: <service-account>
  namespace: <namespace>
EOF
```
where;
- <service-account> is the name of the service account that you want to create.
- <namespace> is the namespace that you created in step 1 above.

Create a cluster role:

kubectl create -f - <<EOF
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: <cluster-role>
rules:
- apiGroups:
  - ""
  resources:
  - events
  verbs:
  - get
  - list
  - watch
EOF

where;

<cluster-role> is the name of the cluster role that you want to create.

Create a cluster role binding:
```
kubectl create -f - <<EOF
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: <cluster-role-binding>
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: <cluster-role>
subjects:
- kind: ServiceAccount
  name: <service-account>
  namespace: <namespace>
EOF
```
where;
- <cluster-role-binding> is the name of the cluster role binding that you want to create.
- <cluster-role> is the name of the cluster role that you created in step 3 above.
- <service-account> is the name of the service account that you created in step 2 above.
- <namespace> is the name of the namespace that you created in step 1 above.
Create an ApiServerSource object:
- YAML
- kn
```
kubectl create -f - <<EOF
apiVersion: sources.knative.dev/v1
kind: ApiServerSource
metadata:
 name: <apiserversource>
 namespace: <namespace>
spec:
 serviceAccountName: <service-account>
 mode: Resource
 resources:
   - apiVersion: v1
     kind: Event
 sink:
   ref:
     apiVersion: v1
     kind: Service
     name: <sink>
EOF
```
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 above.
- <service-account> is the name of the service account that you created in step 2 above.
- <sink> is the name of the Knative service that you want to use as a sink. A service is used here as an example, however you can use any supported PodSpecable object by updating the kind from Service to another object type.
```
kn source apiserver create <apiserversource> \
  --namespace <namespace> \
  --mode "Resource" \
  --resource "Event:v1" \
  --service-account <service-account> \
  --sink <sink>
```
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 above.
- <service-account> is the name of the service account that you created in step 2 above.
- <sink> is the name of the PodSpecable object that you want to use as a sink.
Create events by launching a test pod in your namespace:
```
kubectl run busybox --image=busybox --namespace=<namespace> --restart=Never -- ls
```
where;
- <namespace> is the name of the namespace that you created in step 1 above.
Delete the test pod:
```
kubectl --namespace=<namespace> delete pod busybox
```
where;
- <namespace> is the name of the namespace that you created in step 1 above.

View the logs to verify that Kubernetes events were sent to the Knative Eventing system:

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

where;

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

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 API server source

Deleting the namespace removes the API server source and all of the related resources that were created in this namespace:

kubectl delete namespace <namespace>

where;

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