// Module included in the following assemblies:
//
// * serverless/eventing/event-sources/serverless-apiserversource.adoc

:_mod-docs-content-type: PROCEDURE
[id="apiserversource-yaml_{context}"]
= Creating an API server source by using YAML files

Creating Knative resources by using YAML files uses a declarative API, which enables you to describe event sources declaratively and in a reproducible manner. To create an API server source by using YAML, you must create a YAML file that defines an `ApiServerSource` object, then apply it by using the `oc apply` command.

.Prerequisites

* The {ServerlessOperatorName} and Knative Eventing are installed on the cluster.
* You have created a project or have access to a project with the appropriate roles and permissions to create applications and other workloads in {product-title}.
* You have created the `default` broker in the same namespace as the one defined in the API server source YAML file.
* Install the OpenShift CLI (`oc`).

.Procedure

include::snippets/serverless-service-account-apiserversource.adoc[]

. Create an API server source as a YAML file:
+
[source,yaml]
----
apiVersion: sources.knative.dev/v1alpha1
kind: ApiServerSource
metadata:
  name: testevents
spec:
  serviceAccountName: events-sa
  mode: Resource
  resources:
    - apiVersion: v1
      kind: Event
  sink:
    ref:
      apiVersion: eventing.knative.dev/v1
      kind: Broker
      name: default
----

. Apply the `ApiServerSource` YAML file:
+
[source,terminal]
----
$ oc apply -f <filename>
----

. To check that the API server source is set up correctly, create a Knative service as a YAML file that dumps incoming messages to its log:
+
[source,yaml]
----
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: event-display
  namespace: default
spec:
  template:
    spec:
      containers:
        - image: quay.io/openshift-knative/knative-eventing-sources-event-display:latest
----

. Apply the `Service` YAML file:
+
[source,terminal]
----
$ oc apply -f <filename>
----

. Create a `Trigger` object as a YAML file that filters events from the `default` broker to the service created in the previous step:
+
[source,yaml]
----
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: event-display-trigger
  namespace: default
spec:
  broker: default
  subscriber:
    ref:
      apiVersion: serving.knative.dev/v1
      kind: Service
      name: event-display
----

. Apply the `Trigger` YAML file:
+
[source,terminal]
----
$ oc apply -f <filename>
----

. Create events by launching a pod in the default namespace:
+
[source,terminal]
----
$ oc create deployment hello-node --image=quay.io/openshift-knative/knative-eventing-sources-event-display
----

. Check that the controller is mapped correctly, by entering the following command and inspecting the output:
+
[source,terminal]
----
$ oc get apiserversource.sources.knative.dev testevents -o yaml
----
+
.Example output
[source,yaml]
----
apiVersion: sources.knative.dev/v1alpha1
kind: ApiServerSource
metadata:
  annotations:
  creationTimestamp: "2020-04-07T17:24:54Z"
  generation: 1
  name: testevents
  namespace: default
  resourceVersion: "62868"
  selfLink: /apis/sources.knative.dev/v1alpha1/namespaces/default/apiserversources/testevents2
  uid: 1603d863-bb06-4d1c-b371-f580b4db99fa
spec:
  mode: Resource
  resources:
  - apiVersion: v1
    controller: false
    controllerSelector:
      apiVersion: ""
      kind: ""
      name: ""
      uid: ""
    kind: Event
    labelSelector: {}
  serviceAccountName: events-sa
  sink:
    ref:
      apiVersion: eventing.knative.dev/v1
      kind: Broker
      name: default
----

.Verification

To verify that the Kubernetes events were sent to Knative, you can look at the message dumper function logs.

. Get the pods by entering the following command:
+
[source,terminal]
----
$ oc get pods
----
. View the message dumper function logs for the pods by entering the following command:
+
[source,terminal]
----
$ oc logs $(oc get pod -o name | grep event-display) -c user-container
----
+
.Example output
[source,terminal]
----
☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.apiserver.resource.update
  datacontenttype: application/json
  ...
Data,
  {
    "apiVersion": "v1",
    "involvedObject": {
      "apiVersion": "v1",
      "fieldPath": "spec.containers{hello-node}",
      "kind": "Pod",
      "name": "hello-node",
      "namespace": "default",
       .....
    },
    "kind": "Event",
    "message": "Started container",
    "metadata": {
      "name": "hello-node.159d7608e3a3572c",
      "namespace": "default",
      ....
    },
    "reason": "Started",
    ...
  }
----

.Deleting the API server source

. Delete the trigger:
+
[source,terminal]
----
$ oc delete -f trigger.yaml
----

. Delete the event source:
+
[source,terminal]
----
$ oc delete -f k8s-events.yaml
----

. Delete the service account, cluster role, and cluster binding:
+
[source,terminal]
----
$ oc delete -f authentication.yaml
----