Gateway API

Gateway API is a set of resources for configuring networking in Kubernetes. It expands on Ingress to configure additional types of routes such as TCP, UDP, and TLS in addition to HTTP/HTTPS, and to support backends other than Service, and manage the proxies that implement routes.

Gateway API resources will only be reconciled when the Gateway API CRDs are installed in your cluster before Kong Ingress Controller is started. See the getting started page for installation instructions.

A Gateway resource describes an application or cluster feature that can handle Gateway API routing rules, directing inbound traffic to Services by following the rules provided. For Kong’s implementation, a Gateway corresponds to a Kong Deployment managed by the Ingress controller.

Typically, Gateway API implementations manage the resources associated with a Gateway on behalf of users for creating a Gateway resource triggers automatic provisioning of Deployments, Services, and others with configuration by matching the Gateway’s listeners and addresses. Kong’s implementation does not automatically manage Gateway provisioning.

Because the Kong Deployment and its configuration are not managed automatically, listeners and address configuration are not set for you. You must configure your Deployment and Service to match your Gateway’s configuration.

For example, with the following Gateway:

apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: example
spec:
  gatewayClassName: kong
  listeners:
  - name: proxy
    port: 80
    protocol: HTTP
  - name: proxy-ssl
    port: 443
    protocol: HTTPS
    hostname: kong.example.com
    tls:
      mode: Terminate
      certificateRefs:
        - kind: Secret
          name: kong-example-com-cert
  - name: proxy-tcp-9901
    port: 9901
    protocol: TCP
  - name: proxy-udp-9902
    port: 9902
    protocol: UDP
  - name: proxy-tls-9903
    port: 9903
    protocol: TLS

It requires a proxy Service that includes all the requested listener ports:

apiVersion: v1
kind: Service
metadata:
  name: proxy
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8000
  - port: 443
    protocol: TCP
    targetPort: 8443
  - port: 9901
    protocol: TCP
    targetPort: 9901
  - port: 9902
    protocol: UDP
    targetPort: 9902
  - port: 9903
    protocol: TCP
    targetPort: 9903

You must also configure Kong Gateway’s proxy_listen and stream_listen configuration parameters in the container environment:

KONG_PROXY_LISTEN="0.0.0.0:8000 reuseport backlog=16384, 0.0.0.0:8443 http2 ssl reuseport backlog=16384 http2"
KONG_STREAM_LISTEN="0.0.0.0:9901 reuseport backlog=16384, 0.0.0.0:9902 reuseport backlog=16384 udp", 0.0.0.0:9903 reuseport backlog=16384 ssl"

The Service, proxy_listen, and stream_listen configurations are managed via the Helm chart using the proxy configuration block.

proxy:
  http:
    enabled: true
    servicePort: 80
    containerPort: 8000

  tls:
    enabled: true
    servicePort: 443
    containerPort: 8443

  stream:
    - containerPort: 9901
      servicePort: 9901
      protocol: TCP
    - containerPort: 9902
      servicePort: 9902
      protocol: UDP
    - containerPort: 9903
      servicePort: 9903
      protocol: TCP
      parameters:
        - "ssl"

Ports missing appropriate Kong-side configuration results in an error condition in the Gateway’s status.

message: no Kong listen with the requested protocol is configured for the requested port
reason: PortUnavailable

Listener compatibility and handling multiple Gateways

Each Kong Ingress Controller can be provided with a controller name. If no controller name is provided through the --gateway-api-controller-name field (or CONTROLLER_GATEWAY_API_CONTROLLER_NAME environment variable), the default konghq.com/kic-gateway-controller is used.

Every GatewayClass referencing such a controller in the controllerName field is reconciled by the Kong Ingress Controller. Similarly, every Gateway referencing a GatewayClass that specifies a matching controllerName is reconciled.

Binding Kong Gateway to a Gateway resource

To configure Kong Ingress Controller to reconcile the Gateway resource, you must:

• Set the konghq.com/gatewayclass-unmanaged=true annotation in your GatewayClass resource.
• Configure spec.controllerName in your GatewayClass, as explained in the section on listener compatibility.
• Ensure the spec.gatewayClassName value in your Gateway resource matches the value in metadata.name from your GatewayClass.

You can confirm if Kong Ingress Controller has updated the Gateway by inspecting the list of associated addresses.

kubectl get gateway kong -o=jsonpath='{.status.addresses}' | jq

If an IP address is shown, the Gateway is being managed by Kong:

[
  {
    "type": "IPAddress",
    "value": "10.96.179.122"
  },
  {
    "type": "IPAddress",
    "value": "172.18.0.240"
  }
]

Using Kong Ingress Controller without Kong Gateway Operator results in all Gateway resources with the same spec.controllerName being merged into a single configuration. Kong Gateway deployments are created externally to Kong Ingress Controller, which means that we cannot dynamically control the configuration in response to Gateway listeners.

When using unmanaged mode, Routes from all Gateway instances are merged together and sent to all Kong Gateway instances being managed by the single Kong Ingress Controller.