Creating a private service

By default services deployed through Knative are published to an external IP address, making them public services on a public IP address and with a public URL.

While this is useful for services that need to be accessible from outside of the cluster, frequently you may be building a back-end service which should not be available from outside of the cluster.

Knative provides three ways to enable private services which are only available inside the cluster:

  1. To make all services private, change the default domain to svc.cluster.local by editing the config-domain ConfigMap. This changes all services deployed through Knative to only be published to the cluster.
  2. To make an individual service private, the service or route can be labelled so that it is not published to the external gateway.
  3. Use custom domain mappings.

Label a service to be cluster-local only

To configure a Knative service to only be available on the cluster-local network, and not on the public internet, you can apply the networking.knative.dev/visibility=cluster-local label to a Knative service, a route or a Kubernetes service object.

  • To label a Knative service:

    1. kubectl label kservice ${KSVC_NAME} networking.knative.dev/visibility=cluster-local

    By labeling the Kubernetes service you can restrict visibility in a more fine-grained way. See subroutes for information about tagged routes.

  • To label a route when the route is used directly without a Knative service:

    1. kubectl label route ${ROUTE_NAME} networking.knative.dev/visibility=cluster-local

  • To label a Kubernetes service:

    1. kubectl label service ${SERVICE_NAME} networking.knative.dev/visibility=cluster-local

Example

You can deploy the Hello World sample and then convert it to be an cluster-local service by labelling the service:

  1. kubectl label kservice helloworld-go networking.knative.dev/visibility=cluster-local

You can then verify that the change has been made by verifying the URL for the helloworld-go service:

  1. kubectl get kservice helloworld-go
  3. NAME            URL                                              LATESTCREATED         LATESTREADY           READY   REASON
  4. helloworld-go   http://helloworld-go.default.svc.cluster.local   helloworld-go-2bz5l   helloworld-go-2bz5l   True

The service returns the a URL with the svc.cluster.local domain, indicating the service is only available in the cluster local network.