This post provides you step-by-step instructions to install Knative with Istio on IBM Cloud Kubernetes Service (IKS), build and push your image to IBM Cloud Container Registry and deploy the app. 

Before jumping into the instructions, let’s quickly understand what Knative is and what are its key components.

Knative extends Kubernetes to provide the missing building blocks that developers need to create modern, source-centric, container-based, cloud-native applications.

Each of the components under the Knative project attempt to identify common patterns and codify the best practices shared by successful real-world Kubernetes-based frameworks and applications, such as

• Orchestrating source-to-container workflows
• Routing and managing traffic during deployment
• Scaling and sizing resources based on demand
• Binding running services to eventing ecosystems

Knative focuses on the “boring but difficult” parts that everyone needs, but no one benefits from doing over again on their own. This in-turn frees developers to spend more time writing application code, not worrying about how they are going to build, deploy, monitor, and debug it.

Knative Components

Currently, Knative consists of the following top-level repositories:

• Build and build-templates — automatic, repeatable server-side container builds
• Serving — scale to zero, request-driven compute
• Eventing — management and delivery of events

We expect this list to grow as more areas are identified.

Prerequisites

• Node and npm
• Download and install the ibmcloud command line tool

Setup CLI

• Install the cs (container-service) and cr (container-registry) plugins

ibmcloud plugin install container-service -r Bluemix
ibmcloud plugin install container-registry -r Bluemix

• Authorize ibmcloud:

ibmcloud login

Create a Kubernetes Cluster and Set Up Istio

In this section, you will provision a Kubernetes cluster on IBM Cloud Kubernetes service(IKS) and install Istio + Knative components.

• Setup environment variables

• Follow the steps to Create a Kubernetes Cluster

kubectl apply --filename kubectl apply --filename https://raw.githubusercontent.com/knative/serving/master/third_party/istio-1.0.2/istio.yaml

• Label the default namespace with istio-injection=enabled: kubectl label namespace default istio-injection=enabled
• Monitor the Istio components until all of the components show a STATUS of Running or Completed: kubectl get pods --namespace istio-system
• Install Knative components
• To check Knative installation:

Build and Deploy the App

This section uses a rehash of helloworld-nodejs app. For code samples in other programming languages(Go, Python, C#, Java etc.,), refer Knative serving sample applications 

• Clone the repo and cdinto the cloned folder

git clone https://github.com/VidyasagarMSC/knative-deploy
cd knative-deploy

• Install dependencies

npm install

• Build and Push the Docker image to IBM Cloud Container Registry by replacing <region>and <namespace>values

ibmcloud cr build -t registry.<region>.bluemix.net/<namespace>/knative-node-app .

• Inservice.yaml replace imagevalue and run the below command

apiVersion: serving.knative.dev/v1alpha1 # Current version of Knative
kind: Service
metadata:
  name: knative-node-app # The name of the app
  namespace: default # The namespace the app will use
spec:
  runLatest:
    configuration:
      revisionTemplate:
        spec:
          container:
            image: registry.{REGION}.bluemix.net/{NAMESPACE}/knative-node-app # The URL to the image of the app on IBMCLOUD Registry
            env:
            - name: TARGET # The environment variable printed out by the sample app
              value: "Knative Node App running on IBM Cloud"

kubectl apply --filename service.yaml

• To find the IP address for your service, use kubectl get svc knative-ingressgateway -n istio-systemto get the ingress IP for your cluster. If your cluster is new, it may take sometime for the service to get assigned an external IP address.

export IP_ADDRESS=$(kubectl get svc knative-ingressgateway --namespace istio-system --output 'jsonpath={.status.loadBalancer.ingress[0].ip}')

• To find the URL for your service, use kubectl get services.serving.knative.dev knative-node-app --output jsonpath='{.status.domain}'

export HOST_URL=$(kubectl get services.serving.knative.dev knative-node-app  --output jsonpath='{.status.domain}')

• Now you can make a request to your app to see the result.

 curl -H "Host: ${HOST_URL}" http://${IP_ADDRESS}
Response: Node App running on IBM Cloud

Cleanup

• Run the below command to remove the sample app from your cluster

kubectl delete --filename service.yaml

• To delete the cluster (removes everything), enter the following command:

ibmcloud cs cluster-rm $CLUSTER_NAME

Further Reading

• IBM, Google Give Birth to Knative Serverless Cloud Project 
• Knative Docs