Kourier

This component is GA

Kourier is an Ingress for Knative Serving. Kourier is a lightweight alternative for the Istio ingress as its deployment consists only of an Envoy proxy and a control plane for it.

Kourier is passing the knative serving e2e and conformance tests: Kourier Testgrid.

• Getting started
• Features
• Deployment
• Development
• License

Getting started

• Install Knative Serving, ideally without Istio:

kubectl apply -f https://github.com/knative/serving/releases/latest/download/serving-crds.yaml
kubectl apply -f https://github.com/knative/serving/releases/latest/download/serving-core.yaml

• Then install Kourier:

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

• Configure Knative Serving to use the proper "ingress.class":

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

• (OPTIONAL) Set your desired domain (replace 127.0.0.1.nip.io to your preferred domain):

kubectl patch configmap/config-domain \
  -n knative-serving \
  --type merge \
  -p '{"data":{"127.0.0.1.nip.io":""}}'

• (OPTIONAL) Deploy a sample hello world app:

cat <<-EOF | kubectl apply -f -
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: helloworld-go
spec:
  template:
    spec:
      containers:
      - image: gcr.io/knative-samples/helloworld-go
        env:
        - name: TARGET
          value: Go Sample v1
EOF

• (OPTIONAL) For testing purposes, you can use port-forwarding to make requests to Kourier from your machine:

kubectl port-forward --namespace kourier-system $(kubectl get pod -n kourier-system -l "app=3scale-kourier-gateway" --output=jsonpath="{.items[0].metadata.name}") 8080:8080 19000:9000 8443:8443

curl -v -H "Host: helloworld-go.default.127.0.0.1.nip.io" http://localhost:8080

Deployment

By default, the deployment of the Kourier components is split between two different namespaces:

• Kourier control is deployed in the knative-serving namespace
• The kourier gateways are deployed in the kourier-system namespace

To change the Kourier gateway namespace, you will need to:

• Modify the files in config/ and replace all the namespaces fields that have kourier-system with the desired namespace.
• Set the KOURIER_GATEWAY_NAMESPACE env var in the kourier-control deployment to the new namespace.

Features

• Traffic splitting between Knative revisions.
• Automatic update of endpoints as they are scaled.
• Support for gRPC services.
• Timeouts and retries.
• TLS
• Cipher Suite
• External Authorization support.
• Proxy Protocol (AN EXPERIMENTAL / ALPHA FEATURE)

Setup TLS certificate

Create a secret containing your TLS certificate and Private key:

kubectl create secret tls ${CERT_NAME} --key ${KEY_FILE} --cert ${CERT_FILE}

Add the following env vars to net-kourier-controller in the "kourier" container :

CERTS_SECRET_NAMESPACE: ${NAMESPACES_WHERE_THE_SECRET_HAS_BEEN_CREATED}
CERTS_SECRET_NAME: ${CERT_NAME}

Cipher Suites

You can specify the cipher suites for TLS external listener. To specify the cipher suites you want to allow, run the following command to patch config-kourier ConfigMap:

kubectl -n "knative-serving" patch configmap/config-kourier \
  --type merge \
  -p '{"data":{"cipher-suites":"ECDHE-ECDSA-AES128-GCM-SHA256,ECDHE-ECDSA-CHACHA20-POLY1305"}}'

The default uses the default cipher suites of the envoy version.

External Authorization Configuration

If you want to enable the external authorization support you can set these ENV vars in the net-kourier-controller deployment:

• KOURIER_EXTAUTHZ_HOST*: The external authorization service and port, my-auth:2222
• KOURIER_EXTAUTHZ_FAILUREMODEALLOW*: Allow traffic to go through if the ext auth service is down. Accepts true/false
• KOURIER_EXTAUTHZ_PROTOCOL: The protocol used to query the ext auth service. Can be one of : grpc, http, https. Defaults to grpc
• KOURIER_EXTAUTHZ_MAXREQUESTBYTES: Max request bytes, if not set, defaults to 8192 Bytes. More info Envoy Docs
• KOURIER_EXTAUTHZ_TIMEOUT: Max time in ms to wait for the ext authz service. Defaults to 2s
• KOURIER_EXTAUTHZ_PATHPREFIX: If KOURIER_EXTAUTHZ_PROTOCOL is equal to http or https, path to query the ext auth service. Example : if set to /verify, it will query /verify/ (notice the trailing /). If not set, it will query /
• KOURIER_EXTAUTHZ_PACKASBYTES: If KOURIER_EXTAUTHZ_PROTOCOL is equal to grpc, sends the body as raw bytes instead of a UTF-8 string. Accepts only true/false, t/f or 1/0. Attempting to set another value will throw an error. Defaults to false. More info Envoy Docs.

* Required

Proxy Protocol Configuration

Note: this is an experimental/alpha feature.

To enable proxy protocol feature, run the following command to patch config-kourier ConfigMap:

kubectl patch configmap/config-kourier \
  -n knative-serving \
  --type merge \
  -p '{"data":{"enable-proxy-protocol":"true"}}'

Ensure that the file was updated successfully:

kubectl get configmap config-kourier --namespace knative-serving --output yaml

LoadBalancer configuration:

We need to:

• Use your LB provider annotation to enable proxy-protocol.
• If you are planning to enable external-domain-tls, use your LB provider annotation to specify a custom name to use for the Load balancer, This is used to work around the issue of kube-proxy adding external LB address to node local iptables rule, which will break requests to an LB from in-cluster if the LB is expected to terminate SSL or proxy protocol.
• Change the external Traffic Policy to local so the LB we'll preserve the client source IP and avoids a second hop for LoadBalancer.

Example (Scaleway provider):

apiVersion: v1
kind: Service
metadata:
  name: kourier
  namespace: kourier-system
  annotations:
    service.beta.kubernetes.io/scw-loadbalancer-proxy-protocol-v2: '*'
    service.beta.kubernetes.io/scw-loadbalancer-use-hostname: "true"
  labels:
    networking.knative.dev/ingress-provider: kourier
spec:
  ports:
    - name: http2
      port: 80
      protocol: TCP
      targetPort: 8080
    - name: https
      port: 443
      protocol: TCP
      targetPort: 8443
  selector:
    app: 3scale-kourier-gateway
  externalTrafficPolicy: Local
  type: LoadBalancer

Tips

Domain Mapping is configured to explicitly use http2 protocol only. This behaviour can be disabled by adding the following annotation to the Domain Mapping resource

kubectl annotate domainmapping <domain_mapping_name> kourier.knative.dev/disable-http2=true --namespace <namespace>

A good use case for this configuration is DomainMapping with Websocket

Note: This annotation is an experimental/alpha feature. We may change the annotation name in the future.

License

Apache 2.0 License