Installing Knative components using Operator

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/v0.19.0/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 Serving component with different network layers

Knative Operator can configure Knative Serving component with different network layer options. Istio is the default network layer, if the ingress is not specified in the Knative Serving CR. Click on each tab below to see how you can configure Knative Serving with different ingresses:

Ambassador
Contour
Gloo
Kong
Kourier

FEATURE STATE: alpha @ Knative v0.8

The following commands install Ambassador and enable its Knative integration.

Create a namespace to install Ambassador in:
```
kubectl create namespace ambassador
```

Install Ambassador:

kubectl apply --namespace ambassador \
  --filename https://getambassador.io/yaml/ambassador/ambassador-crds.yaml \
  --filename https://getambassador.io/yaml/ambassador/ambassador-rbac.yaml \
  --filename https://getambassador.io/yaml/ambassador/ambassador-service.yaml

Give Ambassador the required permissions:

kubectl patch clusterrolebinding ambassador -p '{"subjects":[{"kind": "ServiceAccount", "name": "ambassador", "namespace": "ambassador"}]}'

Enable Knative support in Ambassador:

kubectl set env --namespace ambassador  deployments/ambassador AMBASSADOR_KNATIVE_SUPPORT=true

To configure Knative Serving to use Ambassador, apply the content of the Serving CR as below:

cat <<-EOF | kubectl apply -f -
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  config:
    network:
      ingress.class: "ambassador.ingress.networking.knative.dev"
EOF

Fetch the External IP or CNAME:
```
kubectl --namespace ambassador get service ambassador
```
Save this for configuring DNS below.

FEATURE STATE: stable @ Knative v0.18

The following commands install Contour and enable its Knative integration.

Install a properly configured Contour:

kubectl apply --filename https://github.com/knative/net-contour/releases/download/v0.19.0/contour.yaml

Install the Knative Contour controller:

kubectl apply --filename https://github.com/knative/net-contour/releases/download/v0.19.0/net-contour.yaml

To configure Knative Serving to use Contour, apply the content of the Serving CR as below:

cat <<-EOF | kubectl apply -f -
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  config:
    network:
      ingress.class: "contour.ingress.networking.knative.dev"
EOF

Fetch the External IP or CNAME:
```
kubectl --namespace contour-external get service envoy
```
Save this for configuring DNS below.

FEATURE STATE: alpha @ Knative v0.8

For a detailed guide on Gloo integration, see Installing Gloo for Knative in the Gloo documentation.

The following commands install Gloo and enable its Knative integration.

Make sure glooctl is installed (version 1.3.x and higher recommended):
```
glooctl version
```
If it is not installed, you can install the latest version using:
```
curl -sL https://run.solo.io/gloo/install | sh
export PATH=$HOME/.gloo/bin:$PATH
```
Or following the Gloo CLI install instructions.

Install Gloo and the Knative integration:

glooctl install knative --install-knative=false

To configure Knative Serving to use Gloo, apply the content of the Serving CR as below:

cat <<-EOF | kubectl apply -f -
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  ingress:
    gloo:
      enabled: true
EOF

Fetch the External IP or CNAME:
```
glooctl proxy url --name knative-external-proxy
```
Save this for configuring DNS below.

FEATURE STATE: @ Knative v0.13

The following commands install Kong and enable its Knative integration.

Install Kong Ingress Controller:

kubectl apply --filename https://raw.githubusercontent.com/Kong/kubernetes-ingress-controller/0.9.x/deploy/single/all-in-one-dbless.yaml

To configure Knative Serving to use Kong, apply the content of the Serving CR as below:

cat <<-EOF | kubectl apply -f -
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  config:
    network:
      ingress.class: "kong"
EOF

Fetch the External IP or CNAME:
```
kubectl --namespace kong get service kong-proxy
```
Save this for configuring DNS below.

FEATURE STATE: beta @ Knative v0.17

The following commands install Kourier and enable its Knative integration.

Install the Knative Kourier controller:

kubectl apply --filename https://github.com/knative/net-kourier/releases/download/v0.19.0/kourier.yaml

To configure Knative Serving to use Kourier, apply the content of the Serving CR as below:

cat <<-EOF | kubectl apply -f -
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  config:
    network:
      ingress.class: "kourier.ingress.networking.knative.dev"
EOF

Fetch the External IP or CNAME:
```
kubectl --namespace knative-serving get service kourier
```
Save this for configuring DNS below.
Configure DNS
We ship a simple Kubernetes Job called “default domain” that will (see caveats) configure Knative Serving to use xip.io as the default DNS suffix.
```
kubectl apply --filename https://github.com/knative/serving/releases/download/v0.19.0/serving-default-domain.yaml
```
Caveat: This will only work if the cluster LoadBalancer service exposes an IPv4 address or hostname, so it will not work with IPv6 clusters or local setups like Minikube. For these, see “Real DNS” or “Temporary DNS”.

To configure DNS for Knative, take the External IP or CNAME from setting up networking, and configure it with your DNS provider as follows:
- If the networking layer produced an External IP address, then configure a wildcard A record for the domain:
```
# Here knative.example.com is the domain suffix for your cluster
*.knative.example.com == A 35.233.41.212
```
- If the networking layer produced a CNAME, then configure a CNAME record for the domain:
```
# Here knative.example.com is the domain suffix for your cluster
*.knative.example.com == CNAME a317a278525d111e89f272a164fd35fb-1510370581.eu-central-1.elb.amazonaws.com
```
Once your DNS provider has been configured, add the following section into your existing Serving CR, and apply it:
```
# Replace knative.example.com with your domain suffix
apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
  namespace: knative-serving
spec:
  config:
    domain:
      "knative.example.com": ""
  ...
```
If you are using curl to access the sample applications, or your own Knative app, and are unable to use the “Magic DNS (xip.io)” or “Real DNS” methods, there is a temporary approach. This is useful for those who wish to evaluate Knative without altering their DNS configuration, as per the “Real DNS” method, or cannot use the “Magic DNS” method due to using, for example, minikube locally or IPv6 clusters.

To access your application using curl using this method:
1. After starting your application, get the URL of your application:
```
kubectl get ksvc
```
  The output should be similar to:
```
NAME            URL                                        LATESTCREATED         LATESTREADY           READY   REASON
helloworld-go   http://helloworld-go.default.example.com   helloworld-go-vqjlf   helloworld-go-vqjlf   True
```
2. Instruct curl to connect to the External IP or CNAME defined by the networking layer in section 3 above, and use the -H "Host:" command-line option to specify the Knative application’s host name. For example, if the networking layer defines your External IP and port to be http://192.168.39.228:32198 and you wish to access the above helloworld-go application, use:
```
curl -H "Host: helloworld-go.default.example.com" http://192.168.39.228:32198
```
  In the case of the provided helloworld-go sample application, using the default configuration, the output should be:
```
Hello Go Sample v1!
```
Refer to the “Real DNS” method for a permanent solution.
Monitor the Knative components until all of the components show a STATUS of Running or Completed:
```
kubectl get pods --namespace knative-serving
```

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/v0.19.0/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/

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