Knative Serving ¶

This package provides serverless functionality using Knative.

Supported Providers ¶

The following table shows the providers this package can work with.

Components ¶

• Knative Serving version: 0.22.0

Configuration ¶

Installation ¶

The Knative Serving package requires use of Contour for ingress. To successfully install and use the Knative Serving package, you must first install Contour.

tanzu package install contour --package-name contour.community.tanzu.vmware.com --version 1.18.1

After the Contour package has been installed, you can install Knative-Serving.

tanzu package install knative-serving --package-name knative-serving.community.tanzu.vmware.com --version 0.22.0

Removal ¶

To remove the Knative-Serving and Contour packages, issue package delete commands.

tanzu package installed delete knative-serving
tanzu package installed delete contour

Usage Example ¶

Official getting started documentation can be found on the Knative site. Provided there are examples for:

• Deploying a Knative service
• Scaling to Zero
• Traffic Splitting

Scale to Zero ¶

This sample demonstrates the scale to zero feature of Knative. You can watch the pods for the application start and quit automatically based on usage. It follows the Knative-Serving Hello World - Go instructions.

Before beginning this guide, knative requires networking layer configuration as a pre-requisite. Be sure to install the Contour package before continuing with this guide.

1. Create a service YAML file for your application.

   cat <<EOF > helloworld-service.yaml
   ---
   apiVersion: v1
   kind: Namespace
   metadata:
     name: example
   ---
   apiVersion: serving.knative.dev/v1
   kind: Service
   metadata:
     name: helloworld-go
     namespace: example
   spec:
     template:
       spec:
         containers:
           - image: gcr.io/knative-samples/helloworld-go
             env:
               - name: TARGET
                 value: "Go Sample v1"
   EOF
   

2. Apply the service manifest

   kubectl apply --filename helloworld-service.yaml
   

3. In a separate terminal window, watch the pods.

   watch kubectl get pods --namespace example
   

4. At this point you will have a Magic DNS (nip.io) configured to provide you access to your service. If you want to use real DNS or any other Magic DNS you’ll need to provide the appropriate configuration to the knative-serving package when installing it.

   NOTE: nip only works if your Contour has a loadbalancer with a reachable IP address. If you don’t have a loadbalancer or have a loadbalancer that only be reached by CNAME, you can use real DNS, see the configuration options for this package.

5. Get the Knative services. This will show which applications are available and the URL to access them.

   kubectl get ksvc --namespace example
   
   NAMESPACE   NAME              URL                                                   LATESTCREATED           LATESTREADY             READY   REASON
   example     helloworld-go     http://helloworld-go.default.18.204.46.247.nip.io     helloworld-go-00001     helloworld-go-00001     True
   

6. Make a request to the application via a cURL of the URL from the previous step.

   curl http://helloworld-go.default.18.204.46.247.nip.io
   
   Hello Go Sample v1!
   

7. If you still have a terminal window open a watch of the pods, keep an eye on the pod for helloworld-go. After about 2 minutes, it should go away. This is Knative scaling to zero, esssentially stopping pods that are not being used. Once the pod has terminated, make another cURL request to your application and you should see the pod re-created on demand.