package
1.12.0
Repository: https://github.com/dapr/go-sdk.git
Documentation: pkg.go.dev

# README

Dapr HTTP Service SDK for Go

Start by importing Dapr Go service/http package:

daprd "github.com/dapr/go-sdk/service/http"

Creating and Starting Service

To create an HTTP Dapr service, first, create a Dapr callback instance with a specific address:

s := daprd.NewService(":8080")

Or with address and an existing http.ServeMux in case you want to combine existing server implementations:

mux := http.NewServeMux()
mux.HandleFunc("/", myOtherHandler)
s := daprd.NewServiceWithMux(":8080", mux)

Once you create a service instance, you can "attach" to that service any number of event, binding, and service invocation logic handlers as shown below. Onces the logic is defined, you are ready to start the service:

if err := s.Start(); err != nil && err != http.ErrServerClosed {
	log.Fatalf("error: %v", err)
}

Event Handling

To handle events from specific topic you need to add at least one topic event handler before starting the service:

sub := &common.Subscription{
	PubsubName: "messages",
	Topic: "topic1",
	Route: "/events",
}
err := s.AddTopicEventHandler(sub, eventHandler)
if err != nil {
	log.Fatalf("error adding topic subscription: %v", err)
}

The handler method itself can be any method with the expected signature:

func eventHandler(ctx context.Context, e *common.TopicEvent) (retry bool, err error) {
	log.Printf("event - PubsubName:%s, Topic:%s, ID:%s, Data: %v", e.PubsubName, e.Topic, e.ID, e.Data)
	// do something with the event
	return true, nil
}

Service Invocation Handler

To handle service invocations you will need to add at least one service invocation handler before starting the service:

if err := s.AddServiceInvocationHandler("/echo", echoHandler); err != nil {
	log.Fatalf("error adding invocation handler: %v", err)
}

The handler method itself can be any method with the expected signature:

func echoHandler(ctx context.Context, in *common.InvocationEvent) (out *common.Content, err error) {
	log.Printf("echo - ContentType:%s, Verb:%s, QueryString:%s, %+v", in.ContentType, in.Verb, in.QueryString, string(in.Data))
	// do something with the invocation here 
	out = &common.Content{
		Data:        in.Data,
		ContentType: in.ContentType,
		DataTypeURL: in.DataTypeURL,
	}
	return
}

Binding Invocation Handler

To handle binding invocations you will need to add at least one binding invocation handler before starting the service:

if err := s.AddBindingInvocationHandler("/run", runHandler); err != nil {
	log.Fatalf("error adding binding handler: %v", err)
}

The handler method itself can be any method with the expected signature:

func runHandler(ctx context.Context, in *common.BindingEvent) (out []byte, err error) {
	log.Printf("binding - Data:%v, Meta:%v", in.Data, in.Metadata)
	// do something with the invocation here 
	return nil, nil
}

Templates

To accelerate your HTTP Dapr app development in Go even further you can use one of the GitHub templates integrating the HTTP Dapr callback package:

Contributing to Dapr Go client

See the Contribution Guide to get started with building and developing.

# Functions

NewService creates new Service.
NewServiceWithMux creates new Service with existing http mux.

# Constants

HealthzRoute Health check default route used by the server.
PubSubHandlerDropStatusCode is the pubsub event appcallback response code indicating that Dapr should drop that message.
PubSubHandlerRetryStatusCode is the error response code (nack) pubsub event appcallback response.
PubSubHandlerSuccessStatusCode is the successful ack code for pubsub event appcallback response.

# Structs

Server is the HTTP server wrapping mux many Dapr helpers.