Installing Knative components using Operator

Knative provides an operator as a tool to install, configure and manage Knative. The Knative operator leverages custom objects in the cluster to define and manage the installed Knative software. This guide explains how to install and uninstall Knative using Knative operator.

Before you begin

Knative installation using the Operator requires the following:

A Kubernetes cluster v1.16 or newer, as well as a compatible kubectl. This guide assumes that you’ve already created a Kubernetes cluster. If you have only one node for your cluster, set CPUs to at least 6, Memory to at least 6.0 GB, Disk storage to at least 30 GB. If you have multiple nodes for your cluster, set CPUs to at least 2, Memory to at least 4.0 GB, Disk storage to at least 20 GB for each node.
The Kubernetes cluster must be able to access the internet, since the Knative operator downloads images online.
Download and install Istio.

Limitations of Knative Operator:

Knative Operator is still in Alpha phase. It has not been tested in a production environment, and should be used for development or test purposes only.

Install Knative with the Knative Operator

You can find the release information of Knative Operator on the Releases page.

Installing the Knative Operator

From releases:

Install the latest Knative operator with the following command:

kubectl apply -f https://github.com/knative/operator/releases/download/v0.18.0/operator.yaml

From source code:

You can also install Knative Operator from source using ko.

Install the ko build tool.
Download the source code using the following command:

git clone https://github.com/knative/operator.git

Install the operator in the root directory of the source using the following command:

ko apply -f config/

Verify the operator installation

Verify the installation of Knative Operator using the command:

kubectl get deployment knative-operator

If the operator is installed correctly, the deployment should show a Ready status. Here is a sample output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
knative-operator   1/1     1            1           19h

Track the log

Use the following command to track the log of the operator:

kubectl logs -f deploy/knative-operator

Installing the Knative Serving component

Create and apply the Knative Serving CR:
You can install the latest available Knative Serving in the operator by applying a YAML file containing the following:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-serving
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
```
If you do not specify a version by using spec.version, the operator defaults to the latest available version.
You do not need to upgrade the operator to a newer version to install new releases of Knative Serving. If Knative Serving launches a new version, e.g. {{spec.version}}, you can install it by applying a YAML file containing the following:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-serving
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  version: {{spec.version}}
  manifests:
    - URL: https://github.com/knative/serving/releases/download/v${VERSION}/serving-core.yaml
    - URL: https://github.com/knative/serving/releases/download/v${VERSION}/serving-hpa.yaml
    - URL: https://github.com/knative/serving/releases/download/v${VERSION}/serving-post-install-jobs.yaml
    - URL: https://github.com/knative/net-istio/releases/download/v0.17.0/net-istio.yaml
```
The field spec.version is used to set the version of Knative Serving. Replace {{spec.version}} with the correct version number. The tag ${VERSION} is automatically replaced with the version number from spec.version by the operator.

The field spec.manifests is used to specify one or multiple URL links of Knative Serving component. Do not forget to add the valid URL of the Knative network ingress plugin. Knative Serving component is still tightly-coupled with a network ingress plugin in the operator. As in the above example, you can use net-istio. The ordering of the URLs is critical. Put the manifest you want to apply first on the top.
The operator provides you the flexibility to install customized Knative Serving based your own requirements. As long as the manifests of customized Knative Serving are accessible to the operator, they can be installed.

For example, the version of the customized Knative Serving is {{spec.version}}, and it is available at https://my-serving/serving.yaml. You choose net-istio as the ingress plugin, which is available at https://my-net-istio/net-istio.yaml. You can create the content of Serving CR as below:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-serving
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  version: {{spec.version}}
  manifests:
    - URL: https://my-serving/serving.yaml
    - URL: https://my-net-istio/net-istio.yaml
```
You can make the customized Knative Serving available in one or multiple links, as the spec.manifests supports a list of links. The ordering of the URLs is critical. Put the manifest you want to apply first on the top. We strongly recommend you to specify the version and the valid links to the customized Knative Serving, by leveraging both spec.version and spec.manifests. Do not skip either field.
Verify the Knative Serving deployment:

kubectl get deployment -n knative-serving

If Knative Serving has been successfully deployed, all deployments of the Knative Serving will show READY status. Here is a sample output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
activator          1/1     1            1           18s
autoscaler         1/1     1            1           18s
autoscaler-hpa     1/1     1            1           14s
controller         1/1     1            1           18s
istio-webhook      1/1     1            1           12s
networking-istio   1/1     1            1           12s
webhook            1/1     1            1           17s

Check the status of Knative Serving Custom Resource:

kubectl get KnativeServing knative-serving -n knative-serving

If Knative Serving is successfully installed, you should see:

NAME              VERSION             READY   REASON
knative-serving   <version number>    True

Installing the Knative Eventing component

Create and apply the Knative Eventing CR:
You can install the latest available Knative Eventing in the operator by applying a YAML file containing the following:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-eventing
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeEventing
metadata:
  name: knative-eventing
  namespace: knative-eventing
```
If you do not specify a version by using spec.version, the operator defaults to the latest available version.
You do not need to upgrade the operator to a newer version to install new releases of Knative Eventing. If Knative Eventing launches a new version, e.g. {{spec.version}}, you can install it by applying a YAML file containing the following:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-eventing
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeEventing
metadata:
  name: knative-eventing
  namespace: knative-eventing
spec:
  version: {{spec.version}}
  manifests:
    - URL: https://github.com/knative/eventing/releases/download/v${VERSION}/eventing.yaml
    - URL: https://github.com/knative/eventing/releases/download/v${VERSION}/eventing-post-install-jobs.yaml
```
The field spec.version is used to set the version of Knative Eventing. Replace {{spec.version}} with the correct version number. The tag ${VERSION} is automatically replaced with the version number from spec.version by the operator.

The field spec.manifests is used to specify one or multiple URL links of Knative Eventing component. Do not forget to add the valid URL of the Knative network ingress plugin. The ordering of the URLs is critical. Put the manifest you want to apply first on the top.
The operator provides you the flexibility to install customized Knative Eventing based your own requirements. As long as the manifests of customized Knative Eventing are accessible to the operator, they can be installed.

For example, the version of the customized Knative Eventing is {{spec.version}}, and it is available at https://my-eventing/eventing.yaml. You can create the content of Eventing CR as below:
```
apiVersion: v1
kind: Namespace
metadata:
 name: knative-eventing
---
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeEventing
metadata:
  name: knative-eventing
  namespace: knative-eventing
spec:
  version: {{spec.version}}
  manifests:
    - URL: https://my-eventing/eventing.yaml
```
You can make the customized Knative Eventing available in one or multiple links, as the spec.manifests supports a list of links. The ordering of the URLs is critical. Put the manifest you want to apply first on the top. We strongly recommend you to specify the version and the valid links to the customized Knative Eventing, by leveraging both spec.version and spec.manifests. Do not skip either field.
Verify the Knative Eventing deployment:

kubectl get deployment -n knative-eventing

If Knative Eventing has been successfully deployed, all deployments of the Knative Eventing will show READY status. Here is a sample output:

NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
broker-controller      1/1     1            1           63s
broker-filter          1/1     1            1           62s
broker-ingress         1/1     1            1           62s
eventing-controller    1/1     1            1           67s
eventing-webhook       1/1     1            1           67s
imc-controller         1/1     1            1           59s
imc-dispatcher         1/1     1            1           59s
mt-broker-controller   1/1     1            1           62s

Check the status of Knative Eventing Custom Resource:

kubectl get KnativeEventing knative-eventing -n knative-eventing

If Knative Eventing is successfully installed, you should see:

NAME               VERSION             READY   REASON
knative-eventing   <version number>    True

Uninstall Knative

Removing the Knative Serving component

Remove the Knative Serving CR:

kubectl delete KnativeServing knative-serving -n knative-serving

Removing Knative Eventing component

Remove the Knative Eventing CR:

kubectl delete KnativeEventing knative-eventing -n knative-eventing

Knative operator prevents unsafe removal of Knative resources. Even if the Knative Serving and Knative Eventing CRs are successfully removed, all the CRDs in Knative are still kept in the cluster. All your resources relying on Knative CRDs can still work.

Removing the Knative Operator:

If you have installed Knative using the Release page, remove the operator using the following command:

kubectl delete -f https://github.com/knative/operator/releases/download/v0.18.0/operator.yaml

If you have installed Knative from source, uninstall it using the following command while in the root directory for the source:

ko delete -f config/

What’s next

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