Resubmit a stored event as a new undelivered event (closes #250)

internal/middleware/ratelimit.go

@@ -44,6 +44,18 @@ const (
 	// replayRateInterval is the time window for the replay limit.
 	replayRateInterval = 1 * time.Minute
 
+	// resubmitRateLimit is the maximum number of event resubmits one
+	// client may queue per interval. A resubmit stores an event and
+	// queues one delivery per active target, so it costs more
+	// outbound work per press than a replay does. Firing a captured
+	// event repeatedly at a backend under development is the point of
+	// the action, so the ceiling stays well above the rate a person
+	// iterates at.
+	resubmitRateLimit = 30
+
+	// resubmitRateInterval is the time window for the resubmit limit.
+	resubmitRateInterval = 1 * time.Minute
+
 	// receiverRateInterval is the time window for the webhook
 	// receiver rate limit. The configured limit is expressed in
 	// requests per minute.
@@ -315,6 +327,22 @@ func (m *Middleware) ReplayRateLimit() func(http.Handler) http.Handler {
 	)
 }
 
+// ResubmitRateLimit returns middleware that enforces per-IP rate
+// limiting on event resubmits.
+//
+// It is a separate bucket from the replay limit so that exhausting one
+// does not take the other away: replay is a recovery action and
+// resubmit is a testing action, and an operator iterating on a backend
+// must not lose the ability to re-send a failed delivery.
+func (m *Middleware) ResubmitRateLimit() func(http.Handler) http.Handler {
+	return m.postRateLimit(
+		resubmitRateLimit,
+		resubmitRateInterval,
+		"event resubmit rate limit exceeded",
+		"Too many resubmits. Please try again later.",
+	)
+}
+
 // postRateLimit builds middleware that enforces a per-IP rate
 // limit on POST requests only; all other methods pass through
 // unaffected. Requests over the limit receive a 429 with the