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Installing Knative using the Operator

Knative provides a Kubernetes Operator to install, configure and manage Knative. You can install the Serving component, Eventing component, or both on your cluster.

Prerequisites

Before installing Knative, you must meet the following prerequisites:

  • For prototyping purposes, Knative works on most local deployments of Kubernetes. For example, you can use a local, one-node cluster that has 2 CPUs and 4 GB of memory.

    Tip

    You can install a local distribution of Knative for development purposes using the Knative Quickstart plugin

  • For production purposes, it is recommended that:

    • If you have only one node in your cluster, you need at least 6 CPUs, 6 GB of memory, and 30 GB of disk storage.
    • If you have multiple nodes in your cluster, for each node you need at least 2 CPUs, 4 GB of memory, and 20 GB of disk storage.
    • You have a cluster that uses Kubernetes v1.22 or newer.
    • You have installed the kubectl CLI.
    • Your Kubernetes cluster must have access to the internet, because Kubernetes needs to be able to fetch images. To pull from a private registry, see Deploying images from a private container registry.

Caution

The system requirements provided are recommendations only. The requirements for your installation might vary, depending on whether you use optional components, such as a networking layer.

Install the Knative Operator

Before you install the Knative Serving and Eventing components, first install the Knative Operator.

Install the latest Knative Operator release

To install the latest stable Operator release, run the command:

kubectl apply -f https://github.com/knative/operator/releases/download/knative-v1.4.1/operator.yaml

You can find information about the released versions of the Knative Operator on the releases page.

Verify your Knative Operator installation

  1. Because the Operator is installed to the default namespace, ensure you set the current namespace to default by running the command:

    kubectl config set-context --current --namespace=default
    
  2. Check the Operator deployment status by running the command:

    kubectl get deployment knative-operator
    

    If the Operator is installed correctly, the deployment shows a Ready status:

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

Track the log

To track the log of the Operator, run the command:

kubectl logs -f deploy/knative-operator

Upgrade the existing custom resources

If you are upgrading an existing Operator install from v1.2 or earlier to v1.3 or later, run the following command to upgrade the existing custom resources to v1beta1:

kubectl create -f https://github.com/knative/operator/releases/download/knative-v1.4.1/operator-post-install.yaml

Installing the Knative Serving component

To install Knative Serving you must create a custom resource (CR), add a networking layer to the CR, and configure DNS.

Create the Knative Serving custom resource

To create the custom resource for the latest available Knative Serving in the Operator:

  1. Copy the following YAML into a file:

    apiVersion: v1
    kind: Namespace
    metadata:
      name: knative-serving
    ---
    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeServing
    metadata:
      name: knative-serving
      namespace: knative-serving
    

    Note

    When you don't specify a version by using spec.version field, the Operator defaults to the latest available version.

  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

Install the networking layer

Knative Operator can configure the 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. If you choose to use the default Istio network layer, you must install Istio on your cluster. Because of this, you might find it easier to configure Kourier as your networking layer.

Click on each of the following tabs to see how you can configure Knative Serving with different ingresses:

The following steps install Kourier and enable its Knative integration:

  1. To configure Knative Serving to use Kourier, add spec.ingress.kourier and spec.config.network to your Serving CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeServing
    metadata:
      name: knative-serving
      namespace: knative-serving
    spec:
      # ...
      ingress:
        kourier:
          enabled: true
      config:
        network:
          ingress-class: "kourier.ingress.networking.knative.dev"
    
  2. Apply the YAML file for your Serving CR by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of your Serving CR file.

  3. Fetch the External IP or CNAME by running the command:

    kubectl --namespace knative-serving get service kourier
    

    Save this for configuring DNS later.

The following steps install Istio to enable its Knative integration:

  1. Install Istio.

  2. If you installed Istio under a namespace other than the default istio-system:

    1. Add spec.config.istio to your Serving CR YAML file as follows:

      apiVersion: operator.knative.dev/v1beta1
      kind: KnativeServing
      metadata:
        name: knative-serving
        namespace: knative-serving
      spec:
        # ...
        config:
          istio:
            local-gateway.<local-gateway-namespace>.knative-local-gateway: "knative-local-gateway.<istio-namespace>.svc.cluster.local"
      

      Where:

      • <local-gateway-namespace> is the local gateway namespace, which is the same as Knative Serving namespace knative-serving.
      • <istio-namespace> is the namespace where Istio is installed.
    2. Apply the YAML file for your Serving CR by running the command:

      kubectl apply -f <filename>.yaml
      

      Where <filename> is the name of your Serving CR file.

  3. Fetch the External IP or CNAME by running the command:

    kubectl get svc istio-ingressgateway -n <istio-namespace>
    

    Save this for configuring DNS later.

The following steps install Contour and enable its Knative integration:

  1. Install a properly configured Contour:

    kubectl apply --filename https://github.com/knative/net-contour/releases/download/knative-v1.4.0/contour.yaml
    
  2. To configure Knative Serving to use Contour, add spec.ingress.contour spec.config.network to your Serving CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeServing
    metadata:
      name: knative-serving
      namespace: knative-serving
    spec:
      # ...
      ingress:
        contour:
          enabled: true
      config:
        network:
          ingress-class: "contour.ingress.networking.knative.dev"
    
  3. Apply the YAML file for your Serving CR by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of your Serving CR file.

  4. Fetch the External IP or CNAME by running the command:

    kubectl --namespace contour-external get service envoy
    

    Save this for configuring DNS later.

Verify the Knative Serving deployment

  1. Monitor the Knative deployments:

    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
    domain-mapping         1/1     1            1           12s
    domainmapping-webhook  1/1     1            1           12s
    webhook                1/1     1            1           17s
    
  2. 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
    

Configure DNS

You can configure DNS to prevent the need to run curl commands with a host header.

The following tabs expand to show instructions for configuring DNS. Follow the procedure for the DNS of your choice:

Knative provides a Kubernetes Job called default-domain that configures Knative Serving to use sslip.io as the default DNS suffix.

kubectl apply -f https://github.com/knative/serving/releases/download/knative-v1.4.0/serving-default-domain.yaml

Warning

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 unless minikube tunnel is running.

In these cases, see the "Real DNS" or "Temporary DNS" tabs.

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 spec.config.domain 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 (sslip.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 mentioned in section 3, 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 helloworld-go application mentioned earlier, 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 is:
    Hello Go Sample v1!
    
    Refer to the "Real DNS" method for a permanent solution.

Installing the Knative Eventing component

To install Knative Eventing you must apply the custom resource (CR). Optionally, you can install the Knative Eventing component with different event sources.

Create the Knative Eventing custom resource

To create the custom resource for the latest available Knative Eventing in the Operator:

  1. Copy the following YAML into a file:

    apiVersion: v1
    kind: Namespace
    metadata:
      name: knative-eventing
    ---
    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    

    Note

    When you do not specify a version by using spec.version field, the Operator defaults to the latest available version.

  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

Where <filename> is the name of the file you created in the previous step.

Installing Knative Eventing with event sources

Knative Operator can configure the Knative Eventing component with different event sources. Click on each of the following tabs to see how you can configure Knative Eventing with different event sources:

To configure Knative Eventing to install Ceph as the event source:

  1. Add spec.source.ceph to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        ceph:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install Apache CouchDB as the event source:

  1. Add spec.source.couchdb to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        couchdb:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install GitHub as the event source:

  1. Add spec.source.github to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        github:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install GitLab as the event source:

  1. Add spec.source.gitlab to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        gitlab:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install Kafka as the event source:

  1. Add spec.source.kafka to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        kafka:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install NATS Streaming as the event source:

  1. Add spec.source.natss to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        natss:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install Prometheus as the event source:

  1. Add spec.source.prometheus to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        prometheus:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install RabbitMQ as the event source,

  1. Add spec.source.rabbitmq to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        rabbitmq:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

To configure Knative Eventing to install Redis as the event source:

  1. Add spec.source.redis to your Eventing CR YAML file as follows:

    apiVersion: operator.knative.dev/v1beta1
    kind: KnativeEventing
    metadata:
      name: knative-eventing
      namespace: knative-eventing
    spec:
      # ...
      source:
        redis:
          enabled: true
    
  2. Apply the YAML file by running the command:

    kubectl apply -f <filename>.yaml
    

    Where <filename> is the name of the file you created in the previous step.

Verify the Knative Eventing deployment

  1. Monitor the Knative deployments:

    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
    eventing-controller     1/1     1            1           43s
    eventing-webhook        1/1     1            1           42s
    imc-controller          1/1     1            1           39s
    imc-dispatcher          1/1     1            1           38s
    mt-broker-controller    1/1     1            1           36s
    mt-broker-filter        1/1     1            1           37s
    mt-broker-ingress       1/1     1            1           37s
    pingsource-mt-adapter   0/0     0            0           43s
    sugar-controller        1/1     1            1           36s
    
  2. 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
    

Uninstalling Knative

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 Serving component

To remove the Knative Serving CR run the command:

kubectl delete KnativeServing knative-serving -n knative-serving

Removing Knative Eventing component

To remove the Knative Eventing CR run the command:

kubectl delete KnativeEventing knative-eventing -n knative-eventing

Removing the Knative Operator:

If you have installed Knative using the release page, remove the operator by running the command:

kubectl delete -f https://github.com/knative/operator/releases/download/knative-v1.4.1/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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