Expose delivery metrics on /metrics (closes #209) (#224)

internal/handlers/handlers.go

@@ -18,6 +18,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/globals"
 	"sneak.berlin/go/webhooker/internal/healthcheck"
 	"sneak.berlin/go/webhooker/internal/logger"
+	"sneak.berlin/go/webhooker/internal/metrics"
 	"sneak.berlin/go/webhooker/internal/middleware"
 	"sneak.berlin/go/webhooker/internal/session"
 	"sneak.berlin/go/webhooker/templates"
@@ -73,6 +74,7 @@ type Handlers struct {
 	mw        *middleware.Middleware
 	notifier  delivery.Notifier
 	evictor   delivery.WebhookEvictor
+	mtr       *metrics.Set
 	templates map[string]*template.Template
 
 	// dummyVerifications counts the equivalent-cost verifications
@@ -114,6 +116,7 @@ func New(
 	s.mw = params.Middleware
 	s.notifier = params.Notifier
 	s.evictor = params.Evictor
+	s.mtr = metrics.Default()
 
 	// Parse all page templates once at startup
 	s.templates = map[string]*template.Template{

internal/handlers/webhook.go

@@ -217,6 +217,11 @@ func (h *Handlers) createAndDeliverEvent(
 		return
 	}
 
+	// Counted here, after the commit: an event is received once it
+	// is durably stored, which is what the delivery counters are
+	// compared against on a dashboard.
+	h.mtr.EventReceived()
+
 	h.finishWebhookResponse(w, event, entrypoint, tasks)
 }