Show each webhook's activity in the webhook list (closes #394)

Each entry in the webhook list now shows when the webhook's last event
arrived, or "No events yet", and how many of its deliveries failed in
the last 24 hours, in red when that is not zero. The entrypoint and
target counts say how many are inactive.

The figures come from the statistics pane's own reads: the event totals
row, which now also gives the event count, shown as events within
retention, instead of counting every stored event, and the pane's query
over the deliveries finished in the last 24 hours. A webhook whose event
database cannot be read says so in its entry rather than showing zeros.

Model: opus-5-5

README.md

@@ -1768,7 +1768,7 @@ retries) is individually logged for full observability.
 #### EventTotals and TargetTotals
 
 Running counts in each event database, read by the statistics pane at the
-top of the webhook page. `EventTotals` is one row:
+top of the webhook page and by the webhook list. `EventTotals` is one row:
 
 | Field            | Type      | Description |
 | ---------------- | --------- | ----------- |
@@ -1800,6 +1800,14 @@ target. Its failure percentage for a window is the deliveries that became
 `failed` in it out of all that became `delivered` or `failed` in it, and
 a dash when none did.
 
+The webhook list at `/hooks` shows three of the pane's figures for each
+webhook: its events within retention and its last event, both from
+`EventTotals`, and its deliveries that failed in the last 24 hours,
+counted with the pane's query. It opens each webhook's event database once
+(the handle stays open) and runs those two reads there, so its cost grows
+with the number of webhooks and, for each, with the deliveries that
+finished in the last 24 hours, never with the events stored.
+
 #### Event-tier indexes
 
 These indexes on the per-webhook event databases are declared in the model
@@ -1807,7 +1815,7 @@ tags, so `AutoMigrate` creates them on a fresh database:
 
 | Table              | Columns                     | Serves |
 | ------------------ | --------------------------- | ------ |
-| `deliveries`       | `status`, `deleted_at`, `finished_at`, `target_id` | Startup recovery, the retry and pending sweeps every 60 seconds and the queue-depth sampler every 30 seconds, which select deliveries by status, and the webhook page's statistics, which count each target's deliveries by status and when they finished |
+| `deliveries`       | `status`, `deleted_at`, `finished_at`, `target_id` | Startup recovery, the retry and pending sweeps every 60 seconds and the queue-depth sampler every 30 seconds, which select deliveries by status, and the webhook page's statistics and the webhook list, which count each target's deliveries by status and when they finished |
 | `deliveries`       | `event_id`, `deleted_at`    | The event log, which loads each event's deliveries, and retention, which counts and deletes the deliveries of expired events |
 | `delivery_results` | `delivery_id`, `deleted_at` | The event log, which loads the attempts of a page's deliveries, and retention, which deletes the attempts of expired events |
 | `events`           | `deleted_at`, `created_at`  | The webhook page's statistics, which count recent events |
@@ -2951,13 +2959,15 @@ Components are wired via Uber fx in this order:
 7. `healthcheck.New` — Health check service
 8. `session.New` — Cookie-based session manager (key from database)
 9. `handlers.New` — HTTP handlers
-10. `middleware.New` — HTTP middleware
-11. `delivery.New` — Event-driven delivery engine
-12. `delivery.NewArchiveSweeper` — Periodic pruning of idle archives
-13. `delivery.Engine` → `delivery.Notifier` — interface bridge
-14. `delivery.Engine` → `delivery.WebhookEvictor` — interface bridge so
+10. `metrics.NewRegistry` — The registry `/metrics` serves
+11. `metrics.New` — The delivery collectors, registered on that registry
+12. `middleware.New` — HTTP middleware
+13. `delivery.New` — Event-driven delivery engine
+14. `delivery.NewArchiveSweeper` — Periodic pruning of idle archives
+15. `delivery.Engine` → `delivery.Notifier` — interface bridge
+16. `delivery.Engine` → `delivery.WebhookEvictor` — interface bridge so
     deleting a webhook releases its archive writer
-15. `server.New` — HTTP server and router
+17. `server.New` — HTTP server and router
 
 The server starts via `fx.Invoke(func(*server.Server, *delivery.Engine,
 *database.RetentionReaper, *delivery.ArchiveSweeper) {})`, which

cmd/webhooker/main.go

@@ -16,6 +16,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/handlers"
 	"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/resetpw"
 	"sneak.berlin/go/webhooker/internal/server"
@@ -177,6 +178,10 @@ func newApp() *fx.App {
 			healthcheck.New,
 			session.New,
 			handlers.New,
+			// The registry /metrics serves, and the delivery
+			// collectors registered on it.
+			metrics.NewRegistry,
+			metrics.New,
 			middleware.New,
 			// The one SSRF guard both target-creation validation
 			// and the delivery dialer consult, so they cannot

internal/delivery/engine.go

@@ -148,6 +148,7 @@ type EngineParams struct {
 	DBManager *database.WebhookDBManager
 	Logger    *logger.Logger
 	SSRFGuard *Guard
+	Metrics   *metrics.Set
 }
 
 // Engine processes queued deliveries in the background
@@ -167,10 +168,10 @@ type Engine struct {
 	retryCh    chan Task
 	workers    int
 
-	// mtr is the delivery metric set. Production wires the
-	// process-wide one; a test can substitute a set registered on
-	// a private registry so its assertions are not disturbed by
-	// deliveries other tests are making at the same time.
+	// mtr is the delivery metric set. Production wires the one
+	// registered on the registry /metrics serves; a test can
+	// substitute a set registered on a registry it holds, so it can
+	// gather what its own deliveries recorded.
 	mtr *metrics.Set
 
 	// targets maps each target type to its implementation.
@@ -204,7 +205,7 @@ func New(
 		deliveryCh: make(chan Task, deliveryChannelSize),
 		retryCh:    make(chan Task, retryChannelSize),
 		workers:    defaultWorkers,
-		mtr:        metrics.Default(),
+		mtr:        params.Metrics,
 	}
 
 	e.initTargets(&http.Client{

internal/delivery/export_test.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/fx"
 	"gorm.io/gorm"
 	"sneak.berlin/go/webhooker/internal/database"
@@ -399,7 +400,7 @@ func NewTestEngine(
 		deliveryCh: make(chan Task, deliveryChannelSize),
 		retryCh:    make(chan Task, retryChannelSize),
 		workers:    workers,
-		mtr:        metrics.Default(),
+		mtr:        metrics.New(prometheus.NewRegistry()),
 	}
 	e.initTargets(client)
 
@@ -414,7 +415,7 @@ func NewTestEngineSmallRetry(
 	e := &Engine{
 		log:     log,
 		retryCh: make(chan Task, 1),
-		mtr:     metrics.Default(),
+		mtr:     metrics.New(prometheus.NewRegistry()),
 	}
 	e.initTargets(nil)
 
@@ -437,7 +438,7 @@ func NewTestEngineWithDB(
 		deliveryCh: make(chan Task, deliveryChannelSize),
 		retryCh:    make(chan Task, retryChannelSize),
 		workers:    workers,
-		mtr:        metrics.Default(),
+		mtr:        metrics.New(prometheus.NewRegistry()),
 	}
 	e.initTargets(client)
 
@@ -445,8 +446,7 @@ func NewTestEngineWithDB(
 }
 
 // ExportSetMetrics substitutes the engine's metric set, so a test can
-// assert on collectors registered on a private registry instead of
-// the process-wide ones every other test is also moving.
+// assert on collectors registered on a registry it holds.
 func (e *Engine) ExportSetMetrics(mtr *metrics.Set) {
 	e.mtr = mtr
 }

internal/delivery/metrics_test.go

@@ -35,9 +35,8 @@ const (
 )
 
 // mIsolate gives the setup's engine a metric set registered on a
-// private registry. The process-wide collectors are moved by every
-// other delivery test running in parallel, so exact assertions are
-// only possible against a registry this test owns.
+// registry this test holds, so its exact assertions can gather from
+// it.
 func mIsolate(
 	t *testing.T, s iSetup,
 ) *prometheus.Registry {

internal/handlers/handlers.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"sync/atomic"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/fx"
 	"sneak.berlin/go/webhooker/internal/database"
 	"sneak.berlin/go/webhooker/internal/delivery"
@@ -64,6 +65,8 @@ type HandlersParams struct {
 	Notifier     delivery.Notifier
 	Evictor      delivery.WebhookEvictor
 	SSRFGuard    *delivery.Guard
+	Metrics      *metrics.Set
+	Registry     *prometheus.Registry
 }
 
 // Handlers provides HTTP handler methods for all application
@@ -129,7 +132,7 @@ func New(
 	s.mw = params.Middleware
 	s.notifier = params.Notifier
 	s.evictor = params.Evictor
-	s.mtr = metrics.Default()
+	s.mtr = params.Metrics
 	s.ssrf = params.SSRFGuard
 
 	// Parse all page templates once at startup

internal/handlers/handlers_test.go

@@ -20,6 +20,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/handlers"
 	"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"
 )
@@ -109,6 +110,8 @@ func newTestApp(
 			func(r *recordingEvictor) delivery.WebhookEvictor {
 				return r
 			},
+			metrics.NewRegistry,
+			metrics.New,
 			middleware.New,
 			delivery.NewGuard,
 			handlers.New,

internal/handlers/metrics.go

@@ -0,0 +1,21 @@
+package handlers
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// HandleMetrics returns the Prometheus scrape handler for the
+// registry built by metrics.NewRegistry, which the HTTP, delivery, Go
+// runtime and process collectors register on. It is what
+// promhttp.Handler builds for the global default registry, including
+// the promhttp_metric_handler_* series that count scrapes, pointed at
+// that registry instead.
+func (s *Handlers) HandleMetrics() http.HandlerFunc {
+	reg := s.params.Registry
+
+	return promhttp.InstrumentMetricHandler(
+		reg, promhttp.HandlerFor(reg, promhttp.HandlerOpts{}),
+	).ServeHTTP
+}

internal/handlers/source_list_test.go

@@ -0,0 +1,355 @@
+package handlers_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"regexp"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm"
+	"gorm.io/gorm/clause"
+	"sneak.berlin/go/webhooker/internal/database"
+	"sneak.berlin/go/webhooker/internal/handlers"
+	"sneak.berlin/go/webhooker/internal/logger"
+	"sneak.berlin/go/webhooker/internal/session"
+)
+
+// failedHighlight is how the list marks a number of failed deliveries
+// that is not zero.
+const failedHighlight = `class="font-medium text-red-600"`
+
+// listWebhook adds a webhook with the given name, owned by the test
+// user.
+func listWebhook(
+	t *testing.T, db *database.Database, name string,
+) *database.Webhook {
+	t.Helper()
+
+	wh := &database.Webhook{UserID: deleteTestUserID, Name: name}
+	require.NoError(t, db.DB().Omit(clause.Associations).Create(wh).Error)
+
+	return wh
+}
+
+// renderWebhookList runs the real webhook list handler as the test user
+// and returns the rendered page.
+func renderWebhookList(
+	t *testing.T, h *handlers.Handlers, sess *session.Session,
+) string {
+	t.Helper()
+
+	cookies := authenticatedCookies(
+		t, sess, deleteTestUserID, deleteTestUsername,
+	)
+
+	w := httptest.NewRecorder()
+	h.HandleSourceList().ServeHTTP(
+		w, getRequest(t, "/hooks", cookies, nil),
+	)
+	require.Equal(t, http.StatusOK, w.Code)
+
+	return w.Body.String()
+}
+
+// listCard returns one webhook's entry in a rendered webhook list, its
+// markup as rendered and its text with the markup taken out and each
+// run of space made one space.
+func listCard(t *testing.T, page, webhookID string) (string, string) {
+	t.Helper()
+
+	_, card, found := strings.Cut(page, `href="/hook/`+webhookID+`"`)
+	require.True(t, found, "the list has no entry for %s", webhookID)
+
+	card, _, _ = strings.Cut(card, "</a>")
+	text := regexp.MustCompile(`<[^>]*>`).ReplaceAllString(card, " ")
+
+	return card, strings.Join(strings.Fields(text), " ")
+}
+
+// receiveEvents posts the given number of events to an entrypoint
+// through the real receiver, and returns the webhook's event database
+// and its events, oldest first.
+func receiveEvents(
+	t *testing.T,
+	h *handlers.Handlers,
+	dbMgr *database.WebhookDBManager,
+	webhookID, path string,
+	count int,
+) (*gorm.DB, []database.Event) {
+	t.Helper()
+
+	router := receiverRouter(h)
+
+	for range count {
+		require.Equal(t, http.StatusOK, postReceiver(t, router, path))
+	}
+
+	webhookDB, err := dbMgr.GetDB(webhookID)
+	require.NoError(t, err)
+
+	events := listEvents(t, webhookDB)
+	require.Len(t, events, count)
+
+	return webhookDB, events
+}
+
+// seedFailingWebhook adds a webhook with two entrypoints, one inactive,
+// and four targets, one inactive. Three events each reach the three
+// active targets. Two deliveries failed in the last 24 hours, one 30
+// hours ago, and one was delivered. It returns the webhook and its
+// newest event.
+func seedFailingWebhook(
+	t *testing.T,
+	h *handlers.Handlers,
+	db *database.Database,
+	dbMgr *database.WebhookDBManager,
+) (*database.Webhook, database.Event) {
+	t.Helper()
+
+	wh := listWebhook(t, db, "failing")
+	path := statsEntrypoint(t, db, wh.ID, true)
+
+	statsEntrypoint(t, db, wh.ID, false)
+
+	first := seedTarget(t, db, wh.ID, database.TargetTypeLog)
+	second := seedTarget(t, db, wh.ID, database.TargetTypeLog)
+
+	seedTarget(t, db, wh.ID, database.TargetTypeLog)
+
+	inactive := seedTarget(t, db, wh.ID, database.TargetTypeLog)
+	require.NoError(t, db.DB().Model(inactive).
+		Update("active", false).Error)
+
+	webhookDB, events := receiveEvents(t, h, dbMgr, wh.ID, path, 3)
+	now := time.Now()
+
+	statsFinish(t, webhookDB,
+		statsDelivery(t, webhookDB, events[0].ID, first.ID),
+		database.DeliveryStatusFailed, now.Add(-30*time.Hour))
+	statsFinish(t, webhookDB,
+		statsDelivery(t, webhookDB, events[1].ID, first.ID),
+		database.DeliveryStatusFailed, now.Add(-time.Hour))
+	statsFinish(t, webhookDB,
+		statsDelivery(t, webhookDB, events[2].ID, first.ID),
+		database.DeliveryStatusFailed, now.Add(-time.Minute))
+	statsFinish(t, webhookDB,
+		statsDelivery(t, webhookDB, events[2].ID, second.ID),
+		database.DeliveryStatusDelivered, now.Add(-time.Minute))
+
+	return wh, events[2]
+}
+
+// seedHealthyWebhook adds a webhook with one entrypoint and one target,
+// both active, and two events, both delivered. It returns the webhook
+// and its newest event.
+func seedHealthyWebhook(
+	t *testing.T,
+	h *handlers.Handlers,
+	db *database.Database,
+	dbMgr *database.WebhookDBManager,
+) (*database.Webhook, database.Event) {
+	t.Helper()
+
+	wh := listWebhook(t, db, "healthy")
+	path := statsEntrypoint(t, db, wh.ID, true)
+	target := seedTarget(t, db, wh.ID, database.TargetTypeLog)
+
+	webhookDB, events := receiveEvents(t, h, dbMgr, wh.ID, path, 2)
+
+	for _, ev := range events {
+		statsFinish(t, webhookDB,
+			statsDelivery(t, webhookDB, ev.ID, target.ID),
+			database.DeliveryStatusDelivered, time.Now())
+	}
+
+	return wh, events[1]
+}
+
+// lastEventText is how the list shows the arrival of an event.
+func lastEventText(ev database.Event) string {
+	return ev.CreatedAt.UTC().Format("2006-01-02 15:04:05 UTC")
+}
+
+// TestSourceList_ShowsActivityOfEachWebhook checks the figures the list
+// shows for a webhook with recent failures, a healthy one, a new one
+// that has received no event, and one without an event database.
+func TestSourceList_ShowsActivityOfEachWebhook(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	failing, failingNewest := seedFailingWebhook(t, h, db, dbMgr)
+	healthy, healthyNewest := seedHealthyWebhook(t, h, db, dbMgr)
+
+	// Creating a webhook creates its event database.
+	fresh := listWebhook(t, db, "fresh")
+	require.NoError(t, dbMgr.CreateDB(fresh.ID))
+
+	quiet := listWebhook(t, db, "quiet")
+
+	page := renderWebhookList(t, h, sess)
+
+	card, text := listCard(t, page, failing.ID)
+	assert.Contains(t, text, "2 entrypoints, 1 inactive "+
+		"4 targets, 1 inactive "+
+		"3 events within retention "+
+		"Last event "+lastEventText(failingNewest)+" "+
+		"2 failed deliveries in the last 24 hours")
+	assert.Contains(t, card,
+		failedHighlight+">2 failed deliveries in the last 24 hours<")
+
+	card, text = listCard(t, page, healthy.ID)
+	assert.Contains(t, text, "1 entrypoint "+
+		"1 target "+
+		"2 events within retention "+
+		"Last event "+lastEventText(healthyNewest)+" "+
+		"0 failed deliveries in the last 24 hours")
+	assert.NotContains(t, text, "inactive")
+	assert.NotContains(t, card, failedHighlight)
+
+	card, text = listCard(t, page, fresh.ID)
+	assert.Contains(t, text, "0 entrypoints "+
+		"0 targets "+
+		"0 events within retention "+
+		"No events yet "+
+		"0 failed deliveries in the last 24 hours")
+	assert.NotContains(t, card, failedHighlight)
+
+	card, text = listCard(t, page, quiet.ID)
+	assert.Contains(t, text, "0 entrypoints "+
+		"0 targets "+
+		"0 events within retention "+
+		"No events yet "+
+		"0 failed deliveries in the last 24 hours")
+	assert.NotContains(t, card, failedHighlight)
+	assert.False(t, dbMgr.DBExists(quiet.ID),
+		"showing the list must not create an event database")
+}
+
+// TestSourceList_CountsOnlyEventsWithinRetention checks that once
+// retention has removed one of a webhook's three events, the list
+// counts the two still stored.
+func TestSourceList_CountsOnlyEventsWithinRetention(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		log   *logger.Logger
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &log)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := &database.Webhook{
+		UserID: deleteTestUserID, Name: "pruned", RetentionDays: 14,
+	}
+	require.NoError(t, db.DB().Omit(clause.Associations).Create(wh).Error)
+
+	path := statsEntrypoint(t, db, wh.ID, true)
+	webhookDB, events := receiveEvents(t, h, dbMgr, wh.ID, path, 3)
+
+	statsAge(t, webhookDB, events[0].ID, time.Now().Add(-15*24*time.Hour))
+	statsPrune(t, db, dbMgr, log, webhookDB)
+	require.Len(t, listEvents(t, webhookDB), 2)
+
+	_, text := listCard(t, renderWebhookList(t, h, sess), wh.ID)
+	assert.Contains(t, text,
+		"1 entrypoint 0 targets 2 events within retention")
+}
+
+// TestSourceList_LastEventSurvivesPruningEveryEvent checks that once
+// retention has removed every event of a webhook, the list still shows
+// when the last one arrived rather than "No events yet".
+func TestSourceList_LastEventSurvivesPruningEveryEvent(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+		log   *logger.Logger
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr, &log)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := &database.Webhook{
+		UserID: deleteTestUserID, Name: "emptied", RetentionDays: 1,
+	}
+	require.NoError(t, db.DB().Omit(clause.Associations).Create(wh).Error)
+
+	path := statsEntrypoint(t, db, wh.ID, true)
+	webhookDB, events := receiveEvents(t, h, dbMgr, wh.ID, path, 1)
+
+	statsAge(t, webhookDB, events[0].ID, time.Now().Add(-50*time.Hour))
+	statsPrune(t, db, dbMgr, log, webhookDB)
+	require.Empty(t, listEvents(t, webhookDB))
+
+	_, text := listCard(t, renderWebhookList(t, h, sess), wh.ID)
+	assert.Contains(t, text,
+		"0 events within retention "+
+			"Last event "+lastEventText(events[0]))
+	assert.NotContains(t, text, "No events yet")
+}
+
+// TestSourceList_UnreadableEventDatabase checks that a webhook whose
+// event database cannot be read says so in its entry instead of
+// showing zeros, and that the rest of the list is still shown.
+func TestSourceList_UnreadableEventDatabase(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h     *handlers.Handlers
+		sess  *session.Session
+		db    *database.Database
+		dbMgr *database.WebhookDBManager
+	)
+
+	app := newTestApp(t, &h, &sess, &db, &dbMgr)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	broken := listWebhook(t, db, "broken")
+	statsEntrypoint(t, db, broken.ID, true)
+
+	brokenDB, err := dbMgr.GetDB(broken.ID)
+	require.NoError(t, err)
+	require.NoError(t,
+		brokenDB.Migrator().DropTable(&database.EventTotals{}))
+
+	quiet := listWebhook(t, db, "quiet")
+
+	page := renderWebhookList(t, h, sess)
+
+	_, text := listCard(t, page, broken.ID)
+	assert.Contains(t, text,
+		"1 entrypoint 0 targets The event figures could not be read.")
+	assert.NotContains(t, text, "events")
+	assert.NotContains(t, text, "failed")
+
+	_, text = listCard(t, page, quiet.ID)
+	assert.Contains(t, text, "No events yet")
+}

internal/handlers/source_management.go

@@ -3,10 +3,12 @@ package handlers
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"net/http"
 	"slices"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/go-chi/chi"
 	"github.com/google/uuid"
@@ -20,9 +22,20 @@ import (
 type WebhookListItem struct {
 	database.Webhook
 
-	EntrypointCount int64
-	TargetCount     int64
+	EntrypointCount         int
+	InactiveEntrypointCount int
+	TargetCount             int
+	InactiveTargetCount     int
+
+	// EventCount is how many events the webhook holds, LastEventAt
+	// when the newest arrived (nil before the first), and
+	// FailedLast24Hours how many of its deliveries failed in the last
+	// 24 hours. When the webhook's event database could not be read,
+	// EventsUnreadable is set and these three are not known.
 	EventCount        int64
+	LastEventAt       *time.Time
+	FailedLast24Hours int64
+	EventsUnreadable  bool
 }
 
 // errMissingURL signals that a required URL was not provided.
@@ -154,7 +167,12 @@ func (h *Handlers) HandleSourceList() http.HandlerFunc {
 			return
 		}
 
-		items := h.buildWebhookListItems(webhooks)
+		items, err := h.buildWebhookListItems(webhooks)
+		if err != nil {
+			h.serverError(w, r, "failed to list webhooks", err)
+
+			return
+		}
 
 		data := map[string]any{
 			"Webhooks": items,
@@ -164,36 +182,115 @@ func (h *Handlers) HandleSourceList() http.HandlerFunc {
 	}
 }
 
-// buildWebhookListItems builds list items with counts.
+// buildWebhookListItems builds the list's entry for each webhook. It
+// fails when the main database cannot be read. A webhook whose event
+// database cannot be read is marked on its own entry, and the error is
+// logged.
 func (h *Handlers) buildWebhookListItems(
 	webhooks []database.Webhook,
-) []WebhookListItem {
+) ([]WebhookListItem, error) {
 	items := make([]WebhookListItem, len(webhooks))
+	since := time.Now().Add(-longWindow)
 
 	for i := range webhooks {
-		items[i].Webhook = webhooks[i]
+		item := &items[i]
+		item.Webhook = webhooks[i]
 
-		h.db.DB().Model(&database.Entrypoint{}).Where(
-			"webhook_id = ?", webhooks[i].ID,
-		).Count(&items[i].EntrypointCount)
+		var err error
 
-		h.db.DB().Model(&database.Target{}).Where(
-			"webhook_id = ?", webhooks[i].ID,
-		).Count(&items[i].TargetCount)
+		item.EntrypointCount, item.InactiveEntrypointCount, err =
+			h.countWithInactive(&database.Entrypoint{}, item.ID)
+		if err != nil {
+			return nil, err
+		}
 
-		if h.dbMgr.DBExists(webhooks[i].ID) {
-			webhookDB, err := h.dbMgr.GetDB(
-				webhooks[i].ID,
+		item.TargetCount, item.InactiveTargetCount, err =
+			h.countWithInactive(&database.Target{}, item.ID)
+		if err != nil {
+			return nil, err
+		}
+
+		// Opening an event database that does not exist would create
+		// it, and it would hold nothing to count.
+		if !h.dbMgr.DBExists(item.ID) {
+			continue
+		}
+
+		err = h.readListEventFigures(item, since)
+		if err != nil {
+			h.log.Error(
+				"failed to read webhook list figures",
+				"webhook_id", item.ID,
+				"error", err,
 			)
-			if err == nil {
-				webhookDB.Model(
-					&database.Event{},
-				).Count(&items[i].EventCount)
-			}
+
+			item.EventsUnreadable = true
 		}
 	}
 
-	return items
+	return items, nil
+}
+
+// countWithInactive returns how many entrypoints or targets, as model
+// says, a webhook has, and how many of them are inactive.
+func (h *Handlers) countWithInactive(
+	model any, webhookID string,
+) (int, int, error) {
+	var active []bool
+
+	err := h.db.DB().Model(model).
+		Where("webhook_id = ?", webhookID).
+		Pluck("active", &active).Error
+	if err != nil {
+		return 0, 0, fmt.Errorf(
+			"reading active flags of webhook %s: %w", webhookID, err,
+		)
+	}
+
+	inactive := 0
+
+	for _, a := range active {
+		if !a {
+			inactive++
+		}
+	}
+
+	return len(active), inactive, nil
+}
+
+// readListEventFigures fills in the figures the list shows from the
+// webhook's event database, with the statistics pane's own queries:
+// the event count and last arrival from the event totals row, and the
+// deliveries that failed since the given time from the deliveries'
+// status index.
+func (h *Handlers) readListEventFigures(
+	item *WebhookListItem, since time.Time,
+) error {
+	webhookDB, err := h.dbMgr.GetDB(item.ID)
+	if err != nil {
+		return err
+	}
+
+	var totals database.EventTotals
+
+	err = webhookDB.Take(&totals).Error
+	if err != nil {
+		return fmt.Errorf("reading event totals: %w", err)
+	}
+
+	item.EventCount = totals.Events - totals.EventsRemoved
+	item.LastEventAt = totals.LastEventAt
+
+	byTarget, err := finishedByTarget(webhookDB, since)
+	if err != nil {
+		return err
+	}
+
+	for _, f := range byTarget {
+		item.FailedLast24Hours += f.Failed
+	}
+
+	return nil
 }
 
 // HandleSourceCreate shows the form to create a new webhook.

internal/metrics/metrics.go

@@ -3,17 +3,18 @@
 // deliveries are attempted, how they end, how long they take, how
 // deep the queues are, and how many circuit breakers are open.
 //
-// The inbound HTTP metrics come from the go-http-metrics recorder in
-// internal/middleware and land on prometheus.DefaultRegisterer. These
-// collectors register there too, so both surfaces are gathered by the
-// one promhttp handler mounted on the authenticated /metrics route.
+// It also builds the registry the authenticated /metrics route
+// serves. In production, these collectors, the inbound HTTP metrics
+// recorded in internal/middleware, and the Go runtime and process
+// collectors all register on that one registry, never on Prometheus's
+// global default.
 package metrics
 
 import (
-	"sync"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"sneak.berlin/go/webhooker/internal/database"
 )
@@ -57,25 +58,31 @@ var knownTargetTypes = []database.TargetType{
 	database.TargetTypeSlack,
 }
 
-// defaultSet is the process-wide metric set, registered on the same
-// registry the HTTP middleware and the /metrics handler already use.
-// It is built on first use rather than in an init so that a test
-// binary that never touches metrics never registers them.
+// NewRegistry returns the registry /metrics serves, carrying the Go
+// runtime and process collectors that Prometheus's global default
+// registry carries, so the go_* and process_* series stay in the
+// scrape.
 //
-//nolint:gochecknoglobals // one process-wide registration, by design
-var defaultSet = sync.OnceValue(func() *Set {
-	return New(prometheus.DefaultRegisterer)
-})
+// A registry of its own, rather than the global default, is what lets
+// two dependency graphs in one process — two tests, say — each
+// register their collectors without the second registration
+// panicking.
+func NewRegistry() *prometheus.Registry {
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(
+		collectors.NewGoCollector(),
+		collectors.NewProcessCollector(
+			collectors.ProcessCollectorOpts{},
+		),
+	)
 
-// Default returns the process-wide metric set.
-func Default() *Set {
-	return defaultSet()
+	return reg
 }
 
 // Set is one registered group of webhooker's delivery collectors.
-// Production uses the single Default set; tests build their own
-// against a private registry so assertions are not disturbed by
-// deliveries other tests are making concurrently.
+// Production builds one on the registry /metrics serves; tests build
+// one on a registry of their own so they can gather what their own
+// deliveries recorded.
 type Set struct {
 	eventsReceived      prometheus.Counter
 	deliveryAttempts    *prometheus.CounterVec
@@ -93,7 +100,7 @@ type Set struct {
 // New registers a full set of delivery collectors on reg and returns
 // it. It panics if reg already holds them, which is the intended
 // behaviour for a duplicate registration.
-func New(reg prometheus.Registerer) *Set {
+func New(reg *prometheus.Registry) *Set {
 	factory := promauto.With(reg)
 
 	s := &Set{

internal/middleware/export_test.go

@@ -10,8 +10,7 @@ import (
 
 // MetricsMiddlewareForTest builds the metrics recording middleware
 // against a caller-supplied recorder, so a test can gather from its
-// own Prometheus registry rather than the process-wide default one
-// that Middleware.Metrics uses.
+// own Prometheus registry without building a whole Middleware.
 func MetricsMiddlewareForTest(
 	rec httpmetrics.Recorder,
 ) func(http.Handler) http.Handler {

internal/middleware/metrics.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/go-chi/chi"
 	httpmetrics "github.com/slok/go-http-metrics/metrics"
-	prommetrics "github.com/slok/go-http-metrics/metrics/prometheus"
 	ghmm "github.com/slok/go-http-metrics/middleware"
 	"github.com/slok/go-http-metrics/middleware/std"
 )
@@ -151,17 +150,17 @@ func (r boundedLabelRecorder) AddInflightRequests(
 
 var _ httpmetrics.Recorder = boundedLabelRecorder{}
 
-// Metrics returns middleware that records Prometheus HTTP metrics on
-// the default registry, which is the one the /metrics route gathers.
+// Metrics returns middleware that records Prometheus HTTP metrics
+// with the Middleware's one recorder, which New builds on the registry
+// the /metrics route serves and NewForTest on a registry of its own.
+// Every call reuses that recorder, so any number of routers can
+// install it.
 func (s *Middleware) Metrics() func(http.Handler) http.Handler {
-	return metricsMiddleware(
-		prommetrics.NewRecorder(prommetrics.Config{}),
-	)
+	return metricsMiddleware(s.metricsRecorder)
 }
 
 // metricsMiddleware builds the recording middleware against a given
-// recorder, so tests can gather from a registry of their own instead
-// of the process-wide default.
+// recorder, so tests can gather from a registry of their own.
 func metricsMiddleware(
 	rec httpmetrics.Recorder,
 ) func(http.Handler) http.Handler {

internal/middleware/metrics_test.go

@@ -57,9 +57,8 @@ const (
 // Server.setupWebhookRoutes inside it. That ordering is the whole
 // defect, so a test that flattens it would prove nothing.
 //
-// The recorder writes to a registry of the test's own rather than the
-// process-wide default one, so each test observes only its own
-// traffic.
+// The recorder writes to a registry of the test's own, so each test
+// observes only its own traffic.
 func metricsTestRouter(
 	t *testing.T,
 	receiverLimit int,
@@ -455,3 +454,29 @@ func TestMetrics_StatusAndSizeStillRecorded(t *testing.T) {
 		"the interceptor must still count written bytes",
 	)
 }
+
+// TestMetrics_WorksOnNewForTestMiddleware pins that a Middleware built
+// by NewForTest has a recorder of its own: its Metrics() serves a
+// request instead of panicking, and a second one does not collide
+// with the first.
+func TestMetrics_WorksOnNewForTestMiddleware(t *testing.T) {
+	t.Parallel()
+
+	log := slog.New(slog.DiscardHandler)
+	cfg := &config.Config{Environment: "prod"}
+	ok := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte(okBody))
+	})
+
+	for range 2 {
+		h := middleware.NewForTest(log, cfg, nil).Metrics()(ok)
+
+		req := httptest.NewRequestWithContext(
+			t.Context(), http.MethodGet, okRoute, nil,
+		)
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, req)
+
+		assert.Equal(t, http.StatusOK, w.Code)
+	}
+}

internal/middleware/middleware.go

@@ -14,6 +14,9 @@ import (
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
 	"github.com/go-chi/cors"
+	"github.com/prometheus/client_golang/prometheus"
+	httpmetrics "github.com/slok/go-http-metrics/metrics"
+	prommetrics "github.com/slok/go-http-metrics/metrics/prometheus"
 	"go.uber.org/fx"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/globals"
@@ -153,6 +156,7 @@ type MiddlewareParams struct {
 	Globals  *globals.Globals
 	Config   *config.Config
 	Session  *session.Session
+	Registry *prometheus.Registry
 }
 
 // Middleware provides HTTP middleware for logging, CORS, auth, and
@@ -162,6 +166,14 @@ type Middleware struct {
 	params  *MiddlewareParams
 	session *session.Session
 
+	// metricsRecorder records the inbound HTTP metrics. New builds
+	// it on the registry /metrics serves, NewForTest on a registry
+	// of its own. Either way it is built once per Middleware and
+	// Metrics reuses it, because building it registers its
+	// collectors, and a second registration on the same registry
+	// panics.
+	metricsRecorder httpmetrics.Recorder
+
 	// loginGuard counts failed credential verifications and bounds
 	// concurrent password hashing. It is built on first use so that
 	// every construction path gets one; see guard().
@@ -180,6 +192,9 @@ func New(
 	s.params = &params
 	s.log = params.Logger.Get()
 	s.session = params.Session
+	s.metricsRecorder = prommetrics.NewRecorder(
+		prommetrics.Config{Registry: params.Registry},
+	)
 
 	return s, nil
 }

internal/middleware/testing.go

@@ -3,12 +3,17 @@ package middleware
 import (
 	"log/slog"
 
+	"github.com/prometheus/client_golang/prometheus"
+	prommetrics "github.com/slok/go-http-metrics/metrics/prometheus"
 	"sneak.berlin/go/webhooker/internal/config"
 	"sneak.berlin/go/webhooker/internal/session"
 )
 
 // NewForTest creates a Middleware with the minimum dependencies
 // needed for testing. This bypasses the fx lifecycle.
+//
+// Its metrics recorder writes to a fresh registry of its own, so
+// Metrics() works on it and two of them never collide.
 func NewForTest(
 	log *slog.Logger,
 	cfg *config.Config,
@@ -20,5 +25,8 @@ func NewForTest(
 			Config: cfg,
 		},
 		session: sess,
+		metricsRecorder: prommetrics.NewRecorder(
+			prommetrics.Config{Registry: prometheus.NewRegistry()},
+		),
 	}
 }

internal/resetpw/resetpw_test.go

@@ -24,6 +24,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/handlers"
 	"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/resetpw"
 	"sneak.berlin/go/webhooker/internal/session"
@@ -163,6 +164,8 @@ func newServerApp(
 			session.New,
 			func() delivery.Notifier { return &noopNotifier{} },
 			func() delivery.WebhookEvictor { return &noopEvictor{} },
+			metrics.NewRegistry,
+			metrics.New,
 			middleware.New,
 			delivery.NewGuard,
 			handlers.New,

internal/server/routes.go

@@ -7,7 +7,6 @@ import (
 	sentryhttp "github.com/getsentry/sentry-go/http"
 	"github.com/go-chi/chi"
 	"github.com/go-chi/chi/middleware"
-	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"sneak.berlin/go/webhooker/static"
 )
 
@@ -149,12 +148,7 @@ func (s *Server) setupRoutes() {
 	if s.params.Config.MetricsAuthEnabled() {
 		s.router.Group(func(r chi.Router) {
 			r.Use(s.mw.MetricsAuth())
-			r.Get(
-				"/metrics",
-				http.HandlerFunc(
-					promhttp.Handler().ServeHTTP,
-				),
-			)
+			r.Get("/metrics", s.h.HandleMetrics())
 		})
 	}
 

internal/server/routes_test.go

@@ -24,6 +24,7 @@ import (
 	"sneak.berlin/go/webhooker/internal/handlers"
 	"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/server"
 	"sneak.berlin/go/webhooker/internal/session"
@@ -113,6 +114,8 @@ func newTestEnvWithConfig(
 			session.New,
 			func() delivery.Notifier { return &noopNotifier{} },
 			func() delivery.WebhookEvictor { return &noopEvictor{} },
+			metrics.NewRegistry,
+			metrics.New,
 			middleware.New,
 			delivery.NewGuard,
 			handlers.New,
@@ -1478,3 +1481,46 @@ func TestMetricsRouteUnmountedOnHalfSetConfig(t *testing.T) {
 		})
 	}
 }
+
+// TestTwoMetricsRoutersInOneProcess pins
+// https://git.eeqj.de/sneak/webhooker/issues/227: a second
+// metrics-enabled router in one process used to panic, because the
+// HTTP metrics registered on Prometheus's global default registry.
+// Two routers are built over separate dependency graphs and a third
+// over the first graph again, and each must still serve the HTTP,
+// delivery, Go runtime and process series, and the series counting
+// scrapes of /metrics itself.
+func TestTwoMetricsRoutersInOneProcess(t *testing.T) {
+	t.Parallel()
+
+	first := newTestEnvWithConfig(
+		t, metricsConfig(t, metricsUser, metricsAuthValue),
+	)
+	second := newTestEnvWithConfig(
+		t, metricsConfig(t, metricsUser, metricsAuthValue),
+	)
+	third := &testEnv{
+		router: server.NewRouterForTest(
+			first.log.Get(), first.cfg, first.mw, first.hnd,
+		),
+	}
+
+	for _, env := range []*testEnv{first, second, third} {
+		env.get("/", nil)
+
+		scrape := env.metricsRequest(metricsUser, metricsAuthValue)
+		require.Equal(t, http.StatusOK, scrape.Code)
+
+		for _, series := range []string{
+			"http_request_duration_seconds",
+			"http_response_size_bytes",
+			"http_requests_inflight",
+			"webhooker_events_received_total",
+			"go_goroutines",
+			"process_start_time_seconds",
+			"promhttp_metric_handler_requests_total",
+		} {
+			assert.Contains(t, scrape.Body.String(), series)
+		}
+	}
+}

templates/sources_list.html

@@ -27,10 +27,16 @@
                 </div>
                 <span class="badge-info">Retention: {{.RetentionLabel}}</span>
             </div>
-            <div class="flex gap-6 mt-4 text-sm text-gray-500">
-                <span>{{.EntrypointCount}} entrypoint{{if ne .EntrypointCount 1}}s{{end}}</span>
-                <span>{{.TargetCount}} target{{if ne .TargetCount 1}}s{{end}}</span>
-                <span>{{.EventCount}} event{{if ne .EventCount 1}}s{{end}}</span>
+            <div class="flex flex-wrap gap-6 mt-4 text-sm text-gray-500">
+                <span>{{.EntrypointCount}} entrypoint{{if ne .EntrypointCount 1}}s{{end}}{{if .InactiveEntrypointCount}}, {{.InactiveEntrypointCount}} inactive{{end}}</span>
+                <span>{{.TargetCount}} target{{if ne .TargetCount 1}}s{{end}}{{if .InactiveTargetCount}}, {{.InactiveTargetCount}} inactive{{end}}</span>
+                {{if .EventsUnreadable}}
+                <span class="text-red-600">The event figures could not be read.</span>
+                {{else}}
+                <span>{{.EventCount}} event{{if ne .EventCount 1}}s{{end}} within retention</span>
+                <span>{{with .LastEventAt}}Last event {{.UTC.Format "2006-01-02 15:04:05 UTC"}}{{else}}No events yet{{end}}</span>
+                <span class="{{if .FailedLast24Hours}}font-medium text-red-600{{end}}">{{.FailedLast24Hours}} failed deliver{{if eq .FailedLast24Hours 1}}y{{else}}ies{{end}} in the last 24 hours</span>
+                {{end}}
             </div>
         </a>
         {{end}}