Installing Knative Serving using YAML files¶

The following commands install Kourier and enable its Knative integration.

1. Install the Knative Kourier controller by running the command:

   kubectl apply -f https://github.com/knative/net-kourier/releases/download/knative-v1.16.0/kourier.yaml
   

2. Configure Knative Serving to use Kourier by default by running the command:

   kubectl patch configmap/config-network \
     --namespace knative-serving \
     --type merge \
     --patch '{"data":{"ingress-class":"kourier.ingress.networking.knative.dev"}}'
   

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

   kubectl --namespace kourier-system get service kourier
   

   Tip

   Save this to use in the following Configure DNS section.

The following commands install Istio and enable its Knative integration.

1. Install a properly configured Istio by following the Advanced Istio installation instructions or by running the command:

   kubectl apply -l knative.dev/crd-install=true -f https://github.com/knative/net-istio/releases/download/knative-v1.16.0/istio.yaml
   kubectl apply -f https://github.com/knative/net-istio/releases/download/knative-v1.16.0/istio.yaml
   

2. Install the Knative Istio controller by running the command:

   kubectl apply -f https://github.com/knative/net-istio/releases/download/knative-v1.16.0/net-istio.yaml
   

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

   kubectl --namespace istio-system get service istio-ingressgateway
   

   Tip

   Save this to use in the following Configure DNS section.

The following commands install Contour and enable its Knative integration.

1. Install a properly configured Contour by running the command:

   kubectl apply -f https://github.com/knative/net-contour/releases/download/knative-v1.16.0/contour.yaml
   

2. Install the Knative Contour controller by running the command:

   kubectl apply -f https://github.com/knative/net-contour/releases/download/knative-v1.16.0/net-contour.yaml
   

3. Configure Knative Serving to use Contour by default by running the command:

   kubectl patch configmap/config-network \
     --namespace knative-serving \
     --type merge \
     --patch '{"data":{"ingress-class":"contour.ingress.networking.knative.dev"}}'
   

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

   kubectl --namespace contour-external get service envoy
   

   Tip

   Save this to use in the following Configure DNS section.

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-v1.16.0/serving-default-domain.yaml

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, direct Knative to use that domain:

  # Replace knative.example.com with your domain suffix
  kubectl patch configmap/config-domain \
    --namespace knative-serving \
    --type merge \
    --patch '{"data":{"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. Configure Knative to use a domain reachable from outside the cluster:

   kubectl patch configmap/config-domain \
         --namespace knative-serving \
         --type merge \
         --patch '{"data":{"example.com":""}}'
   

2. 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
   

3. 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.

Knative also supports the use of the Kubernetes Horizontal Pod Autoscaler (HPA) for driving autoscaling decisions.

• Install the components needed to support HPA-class autoscaling by running the command:

  kubectl apply -f https://github.com/knative/serving/releases/download/knative-v1.16.0/serving-hpa.yaml
  

Knative supports encryption features through cert-manager. Follow the documentation in Serving encryption for more information.