Knative on Kubernetes: A Step-by-Step Guide

Are you looking for a way to run serverless functions on Kubernetes? Look no further than Knative! Knative is an open-source platform that provides a set of building blocks for running serverless workloads on Kubernetes. In this step-by-step guide, we'll walk you through the process of setting up Knative on Kubernetes.

Prerequisites

Before we get started, you'll need to have the following:

• A Kubernetes cluster
• kubectl installed on your local machine
• Helm installed on your local machine

If you don't have a Kubernetes cluster yet, you can create one using a cloud provider like Google Cloud Platform or Amazon Web Services. Once you have a cluster up and running, you can use kubectl to interact with it.

Step 1: Install Istio

Knative requires Istio to be installed on your Kubernetes cluster. Istio is an open-source service mesh that provides traffic management, security, and observability for microservices. To install Istio, you can use the following command:

$ istioctl install

This will install the default Istio configuration on your cluster. If you want to customize the installation, you can use a configuration file.

Step 2: Install Knative Serving

Knative Serving is the component that allows you to run serverless workloads on Kubernetes. To install Knative Serving, you can use Helm. First, add the Knative Helm repository:

$ helm repo add knative https://storage.googleapis.com/knative-releases/release/v0.25.0

Next, install Knative Serving:

$ helm install knative-serving knative/serving --namespace knative-serving

This will install Knative Serving in the knative-serving namespace. You can check the status of the installation using the following command:

$ kubectl get pods --namespace knative-serving

You should see several pods running, including activator, autoscaler, controller, and webhook.

Step 3: Deploy a Sample Application

Now that Knative Serving is installed, let's deploy a sample application to test it out. Knative provides a sample application called helloworld-go that you can use. To deploy the application, use the following command:

$ kubectl apply -f https://raw.githubusercontent.com/knative/docs/master/docs/serving/samples/hello-world/helloworld-go.yaml

This will create a new Knative service called helloworld-go. You can check the status of the service using the following command:

$ kubectl get ksvc helloworld-go

You should see the service listed, along with its URL. To test the service, you can use curl:

$ curl http://helloworld-go.default.example.com

You should see a message that says "Hello World!"

Step 4: Scale the Application

One of the benefits of using Knative is that it allows you to automatically scale your applications based on demand. To test this out, let's generate some traffic to the helloworld-go service. You can use the following command to generate traffic:

$ while true; do curl http://helloworld-go.default.example.com; done

This will continuously send requests to the service. You can monitor the traffic using the following command:

$ kubectl get ksvc helloworld-go --watch

As the traffic increases, you should see the number of pods running increase as well. Knative will automatically scale the application based on the incoming traffic.

Step 5: Clean Up

When you're done testing Knative, you can clean up the resources that you created. To delete the helloworld-go service, use the following command:

$ kubectl delete -f https://raw.githubusercontent.com/knative/docs/master/docs/serving/samples/hello-world/helloworld-go.yaml

To delete Knative Serving, use the following command:

$ helm uninstall knative-serving --namespace knative-serving

To delete Istio, use the following command:

$ istioctl x uninstall --purge

Conclusion

Knative is a powerful platform for running serverless workloads on Kubernetes. With its built-in scaling and traffic management capabilities, it makes it easy to deploy and manage your applications. By following this step-by-step guide, you should now have a good understanding of how to set up and use Knative on Kubernetes. Happy coding!

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