Install Knative in Gardener Clusters

A walkthrough the steps for installing Knative in Gardener shoot clusters.

4 minute read

Overview

This guide walks you through the installation of the latest version of Knative using pre-built images on a Gardener created cluster environment. To set up your own Gardener, see the documentation or have a look at the landscape-setup-template project. To learn more about this open source project, read the blog on kubernetes.io.

Prerequisites

Knative requires a Kubernetes cluster v1.15 or newer.

Steps

Install and Configure kubectl

If you already have kubectl CLI, run kubectl version --short to check the version. You need v1.10 or newer. If your kubectl is older, follow the next step to install a newer version.
Install the kubectl CLI.

Access Gardener

Create a project in the Gardener dashboard. This will essentially create a Kubernetes namespace with the name garden-<my-project>.
Configure access to your Gardener project using a kubeconfig.
If you are not the Gardener Administrator already, you can create a technical user in the Gardener dashboard. Go to the “Members” section and add a service account. You can then download the kubeconfig for your project. You can skip this step if you create your cluster using the user interface; it is only needed for programmatic access, make sure you set export KUBECONFIG=garden-my-project.yaml in your shell.

Creating a Kubernetes Cluster

You can create your cluster using kubectl CLI by providing a cluster specification yaml file. You can find an example for GCP in the gardener/gardener repository. Make sure the namespace matches that of your project. Then just apply the prepared so-called “shoot” cluster CRD with kubectl:

kubectl apply --filename my-cluster.yaml

The easier alternative is to create the cluster following the cluster creation wizard in the Gardener dashboard: shoot creation

Configure kubectl for Your Cluster

You can now download the kubeconfig for your freshly created cluster in the Gardener dashboard or via the CLI as follows:

kubectl --namespace shoot--my-project--my-cluster get secret kubecfg --output jsonpath={.data.kubeconfig} | base64 --decode > my-cluster.yaml

This kubeconfig file has full administrators access to you cluster. For the rest of this guide, be sure you have export KUBECONFIG=my-cluster.yaml set.

Installing Istio

Knative depends on Istio. If your cloud platform offers a managed Istio installation, we recommend installing Istio that way, unless you need the ability to customize your installation.

Otherwise, see the Installing Istio for Knative guide to install Istio.

You must install Istio on your Kubernetes cluster before continuing with these instructions to install Knative.

Installing `cluster-local-gateway` for Serving Cluster-Internal Traffic

If you installed Istio, you can install a cluster-local-gateway within your Knative cluster so that you can serve cluster-internal traffic. If you want to configure your revisions to use routes that are visible only within your cluster, install and use the cluster-local-gateway.

Installing Knative

The following commands install all available Knative components as well as the standard set of observability plugins. Knative’s installation guide - Installing Knative.

If you are upgrading from Knative 0.3.x: Update your domain and static IP address to be associated with the LoadBalancer istio-ingressgateway instead of knative-ingressgateway. Then run the following to clean up leftover resources:
```
kubectl delete svc knative-ingressgateway -n istio-system
kubectl delete deploy knative-ingressgateway -n istio-system
```
If you have the Knative Eventing Sources component installed, you will also need to delete the following resource before upgrading:
```
kubectl delete statefulset/controller-manager -n knative-sources
```
While the deletion of this resource during the upgrade process will not prevent modifications to Eventing Source resources, those changes will not be completed until the upgrade process finishes.

To install Knative, first install the CRDs by running the kubectl apply command once with the -l knative.dev/crd-install=true flag. This prevents race conditions during the install, which cause intermittent errors:

kubectl apply --selector knative.dev/crd-install=true \
--filename https://github.com/knative/serving/releases/download/v0.12.1/serving.yaml \
--filename https://github.com/knative/eventing/releases/download/v0.12.1/eventing.yaml \
--filename https://github.com/knative/serving/releases/download/v0.12.1/monitoring.yaml

To complete the installation of Knative and its dependencies, run the kubectl apply command again, this time without the --selector flag:

kubectl apply --filename https://github.com/knative/serving/releases/download/v0.12.1/serving.yaml \
--filename https://github.com/knative/eventing/releases/download/v0.12.1/eventing.yaml \
--filename https://github.com/knative/serving/releases/download/v0.12.1/monitoring.yaml

Monitor the Knative components until all of the components show a STATUS of Running:

kubectl get pods --namespace knative-serving
kubectl get pods --namespace knative-eventing
kubectl get pods --namespace knative-monitoring

Set Your Custom Domain

Fetch the external IP or CNAME of the knative-ingressgateway:

kubectl --namespace istio-system get service knative-ingressgateway
NAME                     TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)                                      AGE
knative-ingressgateway   LoadBalancer   100.70.219.81   35.233.41.212   80:32380/TCP,443:32390/TCP,32400:32400/TCP   4d

Create a wildcard DNS entry in your custom domain to point to the above IP or CNAME:

*.knative.<my domain> == A 35.233.41.212
# or CNAME if you are on AWS
*.knative.<my domain> == CNAME a317a278525d111e89f272a164fd35fb-1510370581.eu-central-1.elb.amazonaws.com

Adapt your Knative config-domain (set your domain in the data field):

kubectl --namespace knative-serving get configmaps config-domain --output yaml
apiVersion: v1
data:
  knative.<my domain>: ""
kind: ConfigMap
  name: config-domain
  namespace: knative-serving

What’s Next

Now that your cluster has Knative installed, you can see what Knative has to offer.

Deploy your first app with the Getting Started with Knative App Deployment guide.

Get started with Knative Eventing by walking through one of the Eventing Samples.

Install Cert-Manager if you want to use the automatic TLS cert provisioning feature.

Cleaning Up

Use the Gardener dashboard to delete your cluster, or execute the following with kubectl pointing to your garden-my-project.yaml kubeconfig:

kubectl --kubeconfig garden-my-project.yaml --namespace garden--my-project annotate shoot my-cluster confirmation.gardener.cloud/deletion=true

kubectl --kubeconfig garden-my-project.yaml --namespace garden--my-project delete shoot my-cluster

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