feat(metrics): Prometheus collectors and /metrics handler

2026-05-22 12:59:53 +02:00
parent 2be2fdf325
commit 952189eb09
3 changed files with 117 additions and 3 deletions
@@ -0,0 +1,69 @@
+// Package metrics defines and registers the Prometheus collectors
+// exported on /metrics.
+package metrics
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+// Metrics bundles all collectors. Each field is the public handle the
+// rest of the service uses to record observations.
+type Metrics struct {
+	BuildInfo      *prometheus.GaugeVec
+	HTTPRequests   *prometheus.CounterVec
+	UpdateJobs     *prometheus.CounterVec
+	UpdateDuration *prometheus.HistogramVec
+	QueueDepth     prometheus.Gauge
+	LastUpdateTime *prometheus.GaugeVec
+	DockerPingUp   prometheus.Gauge
+}
+
+// New constructs Metrics and registers them with the given registry.
+// Use prometheus.NewRegistry() in tests so collectors don't leak between
+// runs; production code uses prometheus.DefaultRegisterer.
+func New(reg prometheus.Registerer) *Metrics {
+	m := &Metrics{
+		BuildInfo: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Name: "package_updater_build_info",
+			Help: "Always 1. Labels carry version/commit for dashboards.",
+		}, []string{"version", "commit"}),
+		HTTPRequests: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "package_updater_http_requests_total",
+			Help: "HTTP requests handled, labelled by endpoint and status.",
+		}, []string{"endpoint", "status_code"}),
+		UpdateJobs: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "package_updater_update_jobs_total",
+			Help: "Update jobs executed, labelled by project/service/status.",
+		}, []string{"project", "service", "status"}),
+		UpdateDuration: prometheus.NewHistogramVec(prometheus.HistogramOpts{
+			Name:    "package_updater_update_duration_seconds",
+			Help:    "Time taken to pull + up a single service.",
+			Buckets: []float64{0.5, 1, 2, 5, 10, 30, 60, 120, 300},
+		}, []string{"project", "service"}),
+		QueueDepth: prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: "package_updater_queue_depth",
+			Help: "Current number of submissions waiting in the queue.",
+		}),
+		LastUpdateTime: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Name: "package_updater_last_update_timestamp",
+			Help: "Unix timestamp of the most recent successful update per service.",
+		}, []string{"project", "service"}),
+		DockerPingUp: prometheus.NewGauge(prometheus.GaugeOpts{
+			Name: "package_updater_docker_ping_up",
+			Help: "1 if the Docker socket responded to ping, 0 otherwise.",
+		}),
+	}
+	reg.MustRegister(
+		m.BuildInfo, m.HTTPRequests, m.UpdateJobs, m.UpdateDuration,
+		m.QueueDepth, m.LastUpdateTime, m.DockerPingUp,
+	)
+	return m
+}
+
+// Handler returns the /metrics HTTP handler bound to the given registry.
+func Handler(gatherer prometheus.Gatherer) http.Handler {
+	return promhttp.HandlerFor(gatherer, promhttp.HandlerOpts{})
+}