Knative Eventing Sugar Controller

Knative Eventing Sugar Controller will react to special labels and annotations to produce or control eventing resources in a cluster or namespace. This allows cluster operators and developers to focus on creating fewer resources, and the underlying eventing infrastructure is created on-demand, and cleaned up when no longer needed.

Installing

The following command installs the Eventing Sugar Controller:

kubectl apply --filename https://github.com/knative/eventing/releases/download/v0.24.0/eventing-sugar-controller.yaml

Automatic Broker Creation

One way to create a Broker is to manually apply a resource to a cluster using the default settings:

kubectl create -f - <<EOF
apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
  name: default
  namespace: default
EOF

There might be cases where automated Broker creation is desirable, such as on namespace creation, or on Trigger creation. The Sugar controller enables those use-cases:

• When a Namespace is labeled with eventing.knative.dev/injection=enabled, the sugar controller will create a default Broker named “default” in that namespace.
• When a Trigger is annotated with eventing.knative.dev/injection=enabled, the controller will create a Broker named by that Trigger in the Trigger’s Namespace.

When a Broker is deleted and the above labels or annotations are in-use, the Sugar Controller will automatically recreate a default Broker.

Namespace Examples

Creating a “default” Broker when creating a Namespace:

kubectl apply -f - <<EOF
apiVersion: v1
kind: Namespace
metadata:
  name: example
  labels:
    eventing.knative.dev/injection: enabled
EOF

To automatically create a Broker after a namespace exists, label the Namespace:

kubectl label namespace default eventing.knative.dev/injection=enabled

If the Broker named “default” already exists in the Namespace, the Sugar Controller will do nothing.

Trigger Examples

Create a Broker named by a Trigger (spec.broker) in the Trigger’s Namespace:

kubectl apply -f - << EOF
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
  name: hello-sugar
  namespace: hello
  annotations:
    eventing.knative.dev/injection: enabled
spec:
  broker: sugar
  subscriber:
    ref:
      apiVersion: v1
      kind: Service
      name: event-display
EOF

Note: If the named Broker already exists, the Sugar controller will do nothing, and the Trigger will not own the existing Broker.

This will make a Broker called “sugar” in the Namespace “hello”, and attempt to send events to the “event-display” service.

If the Broker of the given name already exists in the Namespace, the Sugar Controller will do nothing.