Amazon SNS HTTP Handler

The snshttp package provides an http.Handler adapter for receiving messages from Amazon SNS over HTTP(s) webhooks. The goal is to reduce the boilerplate necessary to get a new service or endpoint receiving messages from Amazon SNS.

Usage

type EventHandler struct {
  // DefaultHandler provides auto confirmation of subscriptions and ignores
  // unsubscribe events.
  snshttp.DefaultHandler
}

// Notification is called for messages published to the SNS Topic. When using
// DefaultHandler as above this is the only event you need to implement.
func (h *EventHandler) Notification(ctx context.Context, event *snshttp.Notification) error {
  fmt.Printf("id=%q subject=%q message=%q timestamp=%q\n",
    event.MessageID,
    event.Subject,
    event.Message,
    event.Timestamp,
  )

  return nil
}

// snshttp.New returns an http.Handler that will parse the payload and pass the
// event to the provided EventHandler.
snsHandler := snshttp.New(&EventHandler{},
  snshttp.WithAuthentication("sns", "password"),
)

http.Handle("/hooks/sns", snsHandler)

Double Requests

When using authentication Amazon SNS will make an initial request without authentication information to determine which scheme (Basic or Digest) the endpoint is using. Amazon will then make a request using the correct authentication scheme. These double requests will happen for every webhook from SNS but only one will be received by the EventHandler.

Timeouts

Amazon SNS expects a webhook to return a response within 15 seconds, any longer and it considers the request failed and it will try again. Because of this, the context.Context passed to each snshttp.EventHandler receiver has a 15 second timeout set from when the request is received.

Thanks

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