snshttp

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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