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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 and Kong’s implementation of Gateway API are both Generally Available for all users.

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.

Gateway management

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. The 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 this 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

It also matches Kong proxy_listen configuration 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"

Both the Service and proxy_listen configuration 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. All the GatewayClasses referencing such a controller in the controllerName field are reconciled by the Kong Ingress Controller. Similarly, all the Gateways referencing a GatewayClass that specifies a matching controllerName are 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.

In addition, the spec.controllerName in your GatewayClass needs to be properly configured, as explained in the section above. For more information, see kic-flags.

Finally, the spec.gatewayClassName value in your Gateway resource should match the value in metadata.name from your GatewayClass.

You can check to confirm if Kong Ingress Controller has updated the Gateway by inspecting the list of associated addresses. If an IP address is shown, the Gateway is being managed by Kong.

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

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

Gateway’s “publish” Service

When an unmanaged Gateway is reconciled by KIC, it gets annotated with konghq.com/publish-service equal to a Service’s namespaced name configured in --publish-service (and optionally in --publish-service-udp) CLI flag. The annotation value is used by the Gateway controller to determine its Listeners’ statuses.

Once the Gateway’s konghq.com/publish-service annotation is assigned, it will no longer be auto-updated by Kong Ingress Controller to match the --publish-service CLI flag. If, for any reason, any of those change after the annotation is assigned, the Gateway controller will not be able to determine the Gateway’s Listeners’ statuses. Manual intervention will be required to update the annotation to match the CLI flag.

If you’d like to migrate an already annotated Gateway to a KIC installation that uses another --publish-service (or --publish-service-udp), you should modify the Gateway’s annotation to match the CLI flag. Otherwise, you may experience the Gateway controller getting stuck looking up the Service:

One of publish services defined in Gateway's "konghq.com/publish-service" annotation didn't match controller manager's configuration    {"GatewayV1Gateway": {"name":"kong","namespace":"default"}, "namespace": "default", "name": "kong", "service": "kong/kong-proxy", "error": "publish service reference \"kong/kong-proxy\" from Gateway's annotations did not match configured controller manager's publish services (\"kong/new-kong-proxy\")"}