Creating and using Subroutes

Subroutes are most effective when used with multiple revisions. When defining a Knative service/route, the traffic section of the spec can split between the different revisions. For example:

traffic:
- percent: 0
  revisionName: foo
- percent: 40
  revisionName: bar
- percent: 60
  revisionName: baz

This allows anyone targeting the main route to have a 0% chance of hitting revision foo, 40% chance of hitting revision bar and 60% chance of hitting revision baz.

Using tags to create target URLs

The spec defines an attribute called tag. When a tag is applied to a route, an address for the specific traffic target is created.

traffic:
- percent: 0
  revisionName: foo
  tag: staging
- percent: 40
  revisionName: bar
- percent: 60
  revisionName: baz

In the above example, you can access the staging target by accessing staging-<route name>.<namespace>.<domain>. The targets for bar and baz can only be accessed using the main route, <route name>.<namespace>.<domain>.

When a traffic target gets tagged, a new Kubernetes service is created for it so that other services can also access it within the cluster. From the above example, a new Kubernetes service called staging-<route name> will be created in the same namespace. This service has the ability to override the visibility of this specific route by applying the label serving.knative.dev/visibility with value cluster-local. See cluster local routes for more information about how to restrict visibility on the specific route.