NATS SSE

HTTP handlers for NATS server side events

Currently, this library uses a single NATS connection. Auth is handled in functions passed into the constructors.

The example program uses the NATS server's SubjectCollides function to verify auth, but this could be whatever method you want.

Example Auth Function

The auth function can be as simple as needed. Here's an example using the NATS Server module to verify the caller has access to the subject.

var permissions = map[string]string{
	"john": "users.john.*",
	"pete": "users.pete.>",
}

func authFunc(authorization, subject string) bool {

	allowed, ok := permissions[authorization]
	if !ok {
		return false
	}

	return server.SubjectsCollide(allowed, subject)
}

This could be a call out to an external service to verify a JWT or as simple as returning true.

Handlers

It's simple to add handlers to a server. For pub/sub or requests the only requirement is a subject wildcard variable. For KV, you need a variable for bucket and a wildcard variable for key. KV also supports passing the JetStream domain as a query parameter named domain.

Here's a very simple example:

r := http.NewServeMux()

nc, err := nats.Connect(nats.DefaultURL)
if err != nil {
	log.Fatal(err)
}

handler := natssse.NewSubHandler(nc, authFunc)
pubHandler := natssse.NewPubHandler(nc, authFunc)
reqHandler := natssse.NewReqHandler(nc, authFunc)
kvHandler := natssse.NewKVHandler(nc, authFunc)

r.Handle("GET /subscribe/{subject...}", handler)
r.Handle("POST /publish/{subject...}", pubHandler)
r.Handle("POST /request/{subject...}", reqHandler)
r.Handle("POST /kv/{bucket}/{key...}", kvHandler)
r.Handle("GET /kv/{bucket}/{key...}", kvHandler)
log.Fatal(http.ListenAndServe(":8080", r))