Add a lib to label/delabel events as cloudevents extensions

pkg/broker/config/targets.proto

@@ -47,6 +47,9 @@ message Target {
 
   // The Pubsub subscription name for retrying the events.
   string retry_subscription = 8;
+
+  // The broker name that the trigger is referencing.
+  string broker = 9;
 }
 
 // NamespacedTargets is the collection of targets grouped by namespaces.

pkg/broker/eventutil/label.go

@@ -0,0 +1,78 @@
+/*
+Copyright 2020 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package eventutil
+
+import (
+	"strings"
+
+	cloudevents "github.com/cloudevents/sdk-go/v2"
+)
+
+const (
+	// labelPrefix is the prefix for label keys.
+	labelPrefix = "kgcp"
+)
+
+// LabeledEvent is a wrapper of a cloudevent
+// that allows labeling the event.
+type LabeledEvent struct {
+	event *cloudevents.Event
+}
+
+// NewLabeledEvent creates a new LabeledEvent.
+func NewLabeledEvent(e *cloudevents.Event) *LabeledEvent {
+	return &LabeledEvent{event: e}
+}
+
+// WithLabel attaches a label to the event as an extension.
+func (le *LabeledEvent) WithLabel(key, value string) *LabeledEvent {
+	if value == "" {
+		le.event.SetExtension(labelPrefix+key, nil)
+	} else {
+		le.event.SetExtension(labelPrefix+key, value)
+	}
+	return le
+}
+
+// GetLabels gets all the labels as a map.
+func (le *LabeledEvent) GetLabels() map[string]string {
+	m := make(map[string]string)
+	exts := le.event.Extensions()
+	for k, v := range exts {
+		if strings.HasPrefix(strings.ToLower(k), labelPrefix) {
+			m[strings.TrimPrefix(strings.ToLower(k), labelPrefix)] = v.(string)
+		}
+	}
+	return m
+}
+
+// Event returns the LabeledEvent as a cloudevent.
+func (le *LabeledEvent) Event() *cloudevents.Event {
+	return le.event
+}
+
+// Delabeled returns the cloudevent without labels.
+func (le *LabeledEvent) Delabeled() *cloudevents.Event {
+	e := le.event.Clone()
+	for k := range e.Extensions() {
+		if strings.HasPrefix(strings.ToLower(k), labelPrefix) {
+			// Set to nil to delete that extension.
+			e.SetExtension(k, nil)
+		}
+	}
+	return &e
+}

pkg/broker/eventutil/label_test.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2020 Google LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package eventutil
+
+import (
+	"testing"
+
+	cloudevents "github.com/cloudevents/sdk-go/v2"
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestLabeledEevent(t *testing.T) {
+	e := cloudevents.NewEvent()
+	e.SetSource("example/uri")
+	e.SetType("example.type")
+	e.SetData(cloudevents.ApplicationJSON, map[string]string{"hello": "world"})
+	e.SetExtension("custom", "foo")
+
+	wantDelabeled := e.Clone()
+	wantLabeled := e.Clone()
+	wantLabeled.SetExtension("kgcplabel1", "val1")
+	wantLabeled.SetExtension("kgcplabel2", "val2")
+
+	le := NewLabeledEvent(&e).WithLabel("label1", "val1").WithLabel("label2", "val2")
+
+	wantLabels := map[string]string{
+		"label1": "val1",
+		"label2": "val2",
+	}
+	gotLabels := le.GetLabels()
+	if diff := cmp.Diff(wantLabels, gotLabels); diff != "" {
+		t.Errorf("LabeledEvent.GetLabels() (-want,+got): %v", diff)
+	}
+
+	gotDelabeled := le.Delabeled()
+	if diff := cmp.Diff(&wantDelabeled, gotDelabeled); diff != "" {
+		t.Errorf("LabeledEvent.Delabeled() (-want,+got): %v", diff)
+	}
+	gotLabeled := le.Event()
+	if diff := cmp.Diff(&wantLabeled, gotLabeled); diff != "" {
+		t.Errorf("LabeledEvent.Event() (-want,+got): %v", diff)
+	}
+
+	le.WithLabel("label1", "").WithLabel("label2", "")
+	if gotCnt := len(le.GetLabels()); gotCnt != 0 {
+		t.Errorf("Labels count after removing labels got=%d want=0", gotCnt)
+	}
+}