docs/code-samples/eventing/helloworld/helloworld-go/helloworld.go

46 lines
1.7 KiB
Go

package main
import (
"context"
"log"
cloudevents "github.com/cloudevents/sdk-go/v2"
"github.com/google/uuid"
)
func receive(ctx context.Context, event cloudevents.Event) (*cloudevents.Event, cloudevents.Result) {
// Here is where your code to process the event will go.
// In this example we will log the event msg
log.Printf("Event received. \n%s\n", event)
data := &HelloWorld{}
if err := event.DataAs(data); err != nil {
log.Printf("Error while extracting cloudevent Data: %s\n", err.Error())
return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err)
}
log.Printf("Hello World Message from received event %q", data.Msg)
// Respond with another event (optional)
// This is optional and is intended to show how to respond back with another event after processing.
// The response will go back into the knative eventing system just like any other event
newEvent := cloudevents.NewEvent()
// Setting the ID here is not necessary. When using NewDefaultClient the ID is set
// automatically. We set the ID anyway so it appears in the log.
newEvent.SetID(uuid.New().String())
newEvent.SetSource("knative/eventing/samples/hello-world")
newEvent.SetType("dev.knative.samples.hifromknative")
if err := newEvent.SetData(cloudevents.ApplicationJSON, HiFromKnative{Msg: "Hi from helloworld-go app!"}); err != nil {
return nil, cloudevents.NewHTTPResult(500, "failed to set response data: %s", err)
}
log.Printf("Responding with event\n%s\n", newEvent)
return &newEvent, nil
}
func main() {
log.Print("Hello world sample started.")
c, err := cloudevents.NewDefaultClient()
if err != nil {
log.Fatalf("failed to create client, %v", err)
}
log.Fatal(c.StartReceiver(context.Background(), receive))
}