Move metrics to metrics/ pacakge

metrics/metrics.go

@@ -0,0 +1,107 @@
+// Package metrics defines the Prometheus metrics exposed by the ntfy server, and registers them
+// with the default Prometheus registry on import. It is decoupled from the ntfy server, so that
+// call sites can update metrics without depending on the server package.
+package metrics
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// Collectors for all metrics exposed by the server.
+//
+// These are never nil, so that call sites can update them unconditionally. If metrics are
+// disabled, the server never mounts the /metrics handler, and the values are simply never read.
+var (
+	MessagesPublishedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_messages_published_success",
+	})
+	MessagesPublishedFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_messages_published_failure",
+	})
+	MessagesCached = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_messages_cached_total",
+	})
+	MessagePublishDurationMillis = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_message_publish_duration_ms",
+	})
+	FirebasePublishedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_firebase_published_success",
+	})
+	FirebasePublishedFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_firebase_published_failure",
+	})
+	EmailsPublishedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_emails_sent_success",
+	})
+	EmailsPublishedFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_emails_sent_failure",
+	})
+	EmailsReceivedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_emails_received_success",
+	})
+	EmailsReceivedFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_emails_received_failure",
+	})
+	CallsMadeSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_calls_made_success",
+	})
+	CallsMadeFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_calls_made_failure",
+	})
+	UnifiedPushPublishedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_unifiedpush_published_success",
+	})
+	MatrixPublishedSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_matrix_published_success",
+	})
+	MatrixPublishedFailure = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "ntfy_matrix_published_failure",
+	})
+	AttachmentsTotalSize = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_attachments_total_size",
+	})
+	Visitors = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_visitors_total",
+	})
+	Users = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_users_total",
+	})
+	Subscribers = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_subscribers_total",
+	})
+	Topics = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "ntfy_topics_total",
+	})
+	HTTPRequests = prometheus.NewCounterVec(prometheus.CounterOpts{
+		Name: "ntfy_http_requests_total",
+	}, []string{"http_code", "ntfy_code", "http_method"})
+)
+
+// init registers all collectors with the default Prometheus registry. Registration is
+// unconditional: the collectors are only ever exposed if the server mounts the /metrics handler,
+// so there is nothing to be gained by tying registration to the config.
+func init() {
+	prometheus.MustRegister(
+		MessagesPublishedSuccess,
+		MessagesPublishedFailure,
+		MessagesCached,
+		MessagePublishDurationMillis,
+		FirebasePublishedSuccess,
+		FirebasePublishedFailure,
+		EmailsPublishedSuccess,
+		EmailsPublishedFailure,
+		EmailsReceivedSuccess,
+		EmailsReceivedFailure,
+		CallsMadeSuccess,
+		CallsMadeFailure,
+		UnifiedPushPublishedSuccess,
+		MatrixPublishedSuccess,
+		MatrixPublishedFailure,
+		AttachmentsTotalSize,
+		Visitors,
+		Users,
+		Subscribers,
+		Topics,
+		HTTPRequests,
+	)
+}

metrics/metrics_test.go

@@ -0,0 +1,58 @@
+package metrics
+
+import (
+	"sort"
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/stretchr/testify/require"
+)
+
+// expectedMetricNames is the exact set of metrics the server exposes. These names are a public
+// contract: renaming or dropping one silently breaks existing dashboards and alerts.
+var expectedMetricNames = []string{
+	"ntfy_attachments_total_size",
+	"ntfy_calls_made_failure",
+	"ntfy_calls_made_success",
+	"ntfy_emails_received_failure",
+	"ntfy_emails_received_success",
+	"ntfy_emails_sent_failure",
+	"ntfy_emails_sent_success",
+	"ntfy_firebase_published_failure",
+	"ntfy_firebase_published_success",
+	"ntfy_http_requests_total",
+	"ntfy_matrix_published_failure",
+	"ntfy_matrix_published_success",
+	"ntfy_message_publish_duration_ms",
+	"ntfy_messages_cached_total",
+	"ntfy_messages_published_failure",
+	"ntfy_messages_published_success",
+	"ntfy_subscribers_total",
+	"ntfy_topics_total",
+	"ntfy_unifiedpush_published_success",
+	"ntfy_users_total",
+	"ntfy_visitors_total",
+}
+
+func TestRegisteredMetricNames(t *testing.T) {
+	HTTPRequests.WithLabelValues("200", "20000", "GET").Inc()
+	families, err := prometheus.DefaultGatherer.Gather()
+	require.Nil(t, err)
+	names := make([]string, 0)
+	for _, family := range families {
+		if strings.HasPrefix(family.GetName(), "ntfy_") {
+			names = append(names, family.GetName())
+		}
+	}
+	sort.Strings(names)
+	require.Equal(t, expectedMetricNames, names)
+}
+
+func TestCollectors_NeverNil(t *testing.T) {
+	// Call sites update metrics unconditionally, even when metrics are disabled, so no collector
+	// may ever be nil
+	MessagesPublishedSuccess.Inc()
+	MessagesCached.Set(1)
+	HTTPRequests.WithLabelValues("200", "20000", "PUT").Inc()
+}