Routes in multiple namespaces

With the Gateway API, a single Gateway can target routes across multiple namespaces.

This guide assumes that you have installed Gateway API CRDs and a conformant controller.

In the following example:

• acme-lb GatewayClass: The GatewayClass responsible for satisfying Gateway and Route resources.
• multi-ns-gateaway Gateway: The Gateway is configured with a single listener on port 80 which selects routes that have the label product: baz in any namespace. Notice how the routes.namespaces.from field in the listener is set to All.
• gateway-api-example-ns1 and gateway-api-example-ns2 Namespaces: These are the namespaces in which route resources are instantiated.
• http-app-1 and http-app-2 HTTPRoutes: These are two resources that are installed in separate namespaces. These routes will be bound to Gateway multi-ns-gateway for the following reasons:
  • Both have the product: baz label on them.
  • http-app-1 HTTPRoute has spec.gateways.allow set to All. The route owner has opted to allow all Gateways in the cluster to bind to this Route.
  • http-app-2 HTTPRoute has spec.gateways.allow set to FromList and contains a reference to the multi-ns-gateway in default namespace. This means that only the specified Gateway resource can bind to this route. Additional Gateways may be added to this list to allow them to bind to this route.

kind: GatewayClass
apiVersion: networking.x-k8s.io/v1alpha1
metadata:
  name: acme-lb
spec:
  controller: acme.io/gateway-controller
  parametersRef:
    name: acme-lb
    group: acme.io
    kind: Parameters
---
kind: Gateway
apiVersion: networking.x-k8s.io/v1alpha1
metadata:
  name: multi-ns-gateway
spec:
  gatewayClassName: acme-lb
  listeners:  # Use GatewayClass defaults for listener definition.
  - protocol: HTTP
    port: 80
    routes:
      kind: HTTPRoute
      selector:
        matchLabels:
          product: baz
      namespaces:
        from: "All"
---
kind: Namespace
apiVersion: v1
metadata:
  name: gateway-api-example-ns1
---
kind: HTTPRoute
apiVersion: networking.x-k8s.io/v1alpha1
metadata:
  name: http-app-1
  namespace: gateway-api-example-ns1
  labels:
    product: baz
spec:
  gateways:
    allow: All
  hostnames:
  - "foo.com"
  rules:
  - matches:
    - path:
        type: Prefix
        value: /bar
    forwardTo:
    - serviceName: my-foo-service1
      port: 8080
  - matches:
    - headers:
        type: Exact
        values:
          magic: foo
      path:
        type: Prefix
        value: /some/thing
    forwardTo:
    - serviceName: my-foo-service2
      port: 8080
---
kind: Namespace
apiVersion: v1
metadata:
  name: gateway-api-example-ns2
---
kind: HTTPRoute
apiVersion: networking.x-k8s.io/v1alpha1
metadata:
  name: http-app-2
  namespace: gateway-api-example-ns2
  labels:
    product: baz
spec:
  gateways:
    allow: FromList
    gatewayRefs:
    - name: multi-ns-gateway
      namespace: default
  hostnames:
  - "bar.com"
  rules:
  - matches:
    - path:
        type: Prefix
        value: /
    forwardTo:
    - serviceName: my-bar-service1
      port: 8080

Please note that this guide illustrates this feature for HTTPRoute resource only as an example. The same can be accomplished with other route types as well.