Support dispatcher format for triggers

config/core/resources/trigger.yaml

@@ -117,6 +117,9 @@ spec:
                     description: Retry is the minimum number of retries the sender should attempt when sending an event before moving it to the dead letter sink.
                     type: integer
                     format: int32
+                  format:
+                    description: Format is the format used to serialize the event into a http request when delivering the event. It can be json (for structured events), binary (for binary events), or unset.
+                    type: string
               filter:
                 description: 'Filter is the filter to apply against all events from the Broker. Only events that pass this filter will be sent to the Subscriber. If not specified, will default to allowing all events.'
                 type: object

pkg/broker/filter/filter_handler.go

@@ -423,10 +423,15 @@ func (h *Handler) handleDispatchToSubscriberRequest(ctx context.Context, trigger
 		Audience: trigger.Status.SubscriberAudience,
 	}
 
-	h.send(ctx, writer, utils.PassThroughHeaders(request.Header), target, reportArgs, event, trigger, ttl)
+	sendOptions := []kncloudevents.SendOption{}
+	if trigger.Spec.Delivery != nil && trigger.Spec.Delivery.Format != nil {
+		sendOptions = append(sendOptions, kncloudevents.WithEventFormat(trigger.Spec.Delivery.Format))
+	}
+
+	h.send(ctx, writer, utils.PassThroughHeaders(request.Header), target, reportArgs, event, trigger, ttl, sendOptions...)
 }
 
-func (h *Handler) send(ctx context.Context, writer http.ResponseWriter, headers http.Header, target duckv1.Addressable, reportArgs *ReportArgs, event *cloudevents.Event, t *eventingv1.Trigger, ttl int32) {
+func (h *Handler) send(ctx context.Context, writer http.ResponseWriter, headers http.Header, target duckv1.Addressable, reportArgs *ReportArgs, event *cloudevents.Event, t *eventingv1.Trigger, ttl int32, sendOpts ...kncloudevents.SendOption) {
 	additionalHeaders := headers.Clone()
 	additionalHeaders.Set(apis.KnNamespaceHeader, t.GetNamespace())
 
@@ -454,6 +459,10 @@ func (h *Handler) send(ctx context.Context, writer http.ResponseWriter, headers
 		}))
 	}
 
+	if len(sendOpts) > 0 {
+		opts = append(opts, sendOpts...)
+	}
+
 	dispatchInfo, err := h.eventDispatcher.SendEvent(ctx, *event, target, opts...)
 	if err != nil {
 		h.logger.Error("failed to send event", zap.Error(err))

test/rekt/features/trigger/feature.go

@@ -18,6 +18,7 @@ package trigger
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/cloudevents/sdk-go/v2/test"
 	"k8s.io/utils/pointer"
@@ -96,6 +97,39 @@ func TriggerDependencyAnnotation() *feature.Feature {
 	return f
 }
 
+func TriggerSupportsDeliveryFormat() *feature.FeatureSet {
+	return &feature.FeatureSet{
+		Name:     "Trigger supports delivery format",
+		Features: []*feature.Feature{triggerWithDispatcherFormat("json"), triggerWithDispatcherFormat("binary")},
+	}
+}
+
+func triggerWithDispatcherFormat(format string) *feature.Feature {
+	f := feature.NewFeatureNamed(fmt.Sprintf("Trigger supports sending with %s delivery format", format))
+
+	brokerName := feature.MakeRandomK8sName("broker")
+	sourceName := feature.MakeRandomK8sName("source")
+	sinkName := feature.MakeRandomK8sName("sink")
+	triggerName := feature.MakeRandomK8sName("trigger")
+	eventToSend := test.FullEvent()
+
+	f.Setup("Install Broker", broker.Install(brokerName, broker.WithEnvConfig()...))
+	f.Setup("Broker is ready", broker.IsReady(brokerName))
+	f.Setup("Broker is addressable", broker.IsAddressable(brokerName))
+
+	f.Setup("Install Sink", eventshub.Install(sinkName, eventshub.VerifyEventFormat(format), eventshub.StartReceiver))
+
+	f.Setup("Install trigger", trigger.Install(triggerName, trigger.WithBrokerName(brokerName), trigger.WithFormat(format), trigger.WithSubscriber(service.AsKReference(sinkName), "")))
+	f.Setup("Trigger is ready", trigger.IsReady(triggerName))
+
+	f.Requirement("Install source", eventshub.Install(sourceName, eventshub.InputEvent(eventToSend), eventshub.StartSenderToResource(broker.GVR(), brokerName)))
+
+	f.Alpha("trigger").
+		Must("dispatch event with correct format", assert.OnStore(sinkName).MatchReceivedEvent(test.HasId(eventToSend.ID())).AtLeast(1))
+
+	return f
+}
+
 func TriggerWithTLSSubscriber() *feature.Feature {
 	f := feature.NewFeatureNamed("Trigger with TLS subscriber")
 

test/rekt/resources/delivery/delivery.go

@@ -117,6 +117,17 @@ func WithRetry(count int32, backoffPolicy *eventingv1.BackoffPolicyType, backoff
 	}
 }
 
+func WithFormat(format string) manifest.CfgFn {
+	return func(cfg map[string]interface{}) {
+		if _, set := cfg["delivery"]; !set {
+			cfg["delivery"] = map[string]interface{}{}
+		}
+		delivery := cfg["delivery"].(map[string]interface{})
+
+		delivery["format"] = format
+	}
+}
+
 // WithTimeout adds the timeout related config to the config.
 func WithTimeout(timeout string) manifest.CfgFn {
 	return func(cfg map[string]interface{}) {

test/rekt/resources/trigger/trigger.go

@@ -196,6 +196,9 @@ var WithRetry = delivery.WithRetry
 // WithTimeout adds the timeout related config to the config.
 var WithTimeout = delivery.WithTimeout
 
+// WithFormat adds the format related config to a Trigger spec
+var WithFormat = delivery.WithFormat
+
 // Install will create a Trigger resource, augmented with the config fn options.
 func Install(name string, opts ...manifest.CfgFn) feature.StepFn {
 	cfg := map[string]interface{}{

test/rekt/resources/trigger/trigger.yaml

@@ -96,4 +96,7 @@ spec:
     {{ if .delivery.backoffDelay }}
     backoffDelay: "{{ .delivery.backoffDelay}}"
     {{ end }}
+    {{ if .delivery.format }}
+    format: {{ .delivery.format }}
+    {{ end }}
   {{ end }}

test/rekt/trigger_test.go

@@ -81,6 +81,18 @@ func TestTriggerDependencyAnnotation(t *testing.T) {
 	env.Test(ctx, t, trigger.TriggerDependencyAnnotation())
 }
 
+func TestTriggerDeliveryFormat(t *testing.T) {
+	ctx, env := global.Environment(
+		knative.WithKnativeNamespace(system.Namespace()),
+		knative.WithLoggingConfig,
+		knative.WithTracingConfig,
+		k8s.WithEventListener,
+		environment.Managed(t),
+	)
+
+	env.TestSet(ctx, t, trigger.TriggerSupportsDeliveryFormat())
+}
+
 func TestTriggerTLSSubscriber(t *testing.T) {
 	t.Parallel()