06.Knative_App

Integrate Knative into KubeVela

These demonstrations show how KubeVela integrates Knative Configuration/Route to deploy and manage applications. We will deploy an application with Knative Serving Workload, then interact with it using cURL requests.

The demonstrations are verified in Alibaba Kubernetes Cluster v1.18.8 of Hongkong region.

Prerequisites

• Follow the instructions in the installation document to get KubeVela installed.

• Knative Serving v0.21. Refer to Install Knative to install Knative. Remember to:

  • pick Istio as the networking layer
  • choose Magic DNS (xip.io) to configure DNS.

Quick Start

Prepare ComponentDefinition and Application

We need an ComponentDefinition capable of renderring a Service of Knative serving.knative.dev/v1.

apiVersion: core.oam.dev/v1beta1
kind: ComponentDefinition
metadata:
  name: knative-serving
  annotations:
    definition.oam.dev/description: "Knative serving."
spec:
  workload:
    definition:
      apiVersion: serving.knative.dev/v1
      kind: Service
  schematic:
    cue:
      template: |
        output: {
        	apiVersion: "serving.knative.dev/v1"
        	kind:       "Service"
        	spec: {
        		template:
        			spec:
        				containers: [{
        					image: parameter.image
        					env:   parameter.env
        				}]
        	}
        }
        parameter: {
        	image: string
        	env?: [...{
        		// +usage=Environment variable name
        		name: string
        		// +usage=The value of the environment variable
        		value?: string
        		// +usage=Specifies a source the value of this var should come from
        		valueFrom?: {
        			// +usage=Selects a key of a secret in the pod's namespace
        			secretKeyRef: {
        				// +usage=The name of the secret in the pod's namespace to select from
        				name: string
        				// +usage=The key of the secret to select from. Must be a valid secret key
        				key: string
        			}
        		}
        	}]
        }

$ kubectl apply -f ./componentdefinition-knative-serving.yaml

Then we write an application with the newly created ComponentDefinition.

apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
  name: webapp
spec:
  components:
    - name: backend
      type: knative-serving
      properties:
        image: gcr.io/knative-samples/helloworld-go
        env:
          - name: TARGET
            value: "Go Sample v1"

$ kubectl apply -f ./app.yaml

Verify the application

$ kubectl get application
NAME     AGE
webapp   24m

$ kubectl get ksvc
NAME            URL                                                 LATESTCREATED         LATESTREADY           READY   REASON
backend-v1      http://backend-v1.default.47.242.55.215.xip.io      backend-v1-00001      backend-v1-00001      True

$ curl http://backend-v1.default.47.242.55.215.xip.io
Hello Go Sample v1!

Have fun with KubeVela and Knative.