dependency-injected non-global metrics object

pkg/metrics/metrics.go

@@ -1,38 +1,72 @@
 package metrics
 
-import "github.com/prometheus/client_golang/prometheus"
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"k8s.io/klog"
+)
 
 const MetricsNamespace = "adapter"
 
-var PrometheusUp = prometheus.NewGauge(prometheus.GaugeOpts{
-	Namespace: MetricsNamespace,
-	Name:      "prometheus_up",
-	Help:      "1 when adapter is able to reach prometheus, 0 otherwise",
-})
-
-var RegistryMetrics = prometheus.NewGaugeVec(prometheus.GaugeOpts{
-	Namespace: MetricsNamespace,
-	Name:      "registry_metrics",
-	Help:      "number of metrics entries in cache registry",
-}, []string{"registry"})
-
-var Errors = prometheus.NewCounterVec(prometheus.CounterOpts{
-	Namespace: MetricsNamespace,
-	Name:      "errors_total",
-	Help:      "number of errors served",
-}, []string{"type"})
-
-var Rules = prometheus.NewGaugeVec(prometheus.GaugeOpts{
-	Namespace: MetricsNamespace,
-	Name:      "roles",
-	Help:      "number of configured rules",
-}, []string{"type"})
-
-func init() {
-	prometheus.MustRegister(
-		PrometheusUp,
-		RegistryMetrics,
-		Errors,
-		Rules,
-	)
+type ServiceMetrics struct {
+	PrometheusUp    prometheus.Gauge
+	RegistryMetrics *prometheus.GaugeVec
+	Errors          *prometheus.CounterVec
+	Rules           *prometheus.GaugeVec
+	Registry        *prometheus.Registry
+}
+
+func NewMetrics() (*ServiceMetrics, error) {
+	ret := &ServiceMetrics{
+		PrometheusUp: prometheus.NewGauge(prometheus.GaugeOpts{
+			Namespace: MetricsNamespace,
+			Name:      "prometheus_up",
+			Help:      "1 when adapter is able to reach prometheus, 0 otherwise",
+		}),
+
+		RegistryMetrics: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Namespace: MetricsNamespace,
+			Name:      "registry_metrics",
+			Help:      "number of metrics entries in cache registry",
+		}, []string{"registry"}),
+
+		Errors: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Namespace: MetricsNamespace,
+			Name:      "errors_total",
+			Help:      "number of errors served",
+		}, []string{"type"}),
+
+		Rules: prometheus.NewGaugeVec(prometheus.GaugeOpts{
+			Namespace: MetricsNamespace,
+			Name:      "roles",
+			Help:      "number of configured rules",
+		}, []string{"type"}),
+
+		Registry: prometheus.NewRegistry(),
+	}
+
+	for collectorName, collector := range map[string]prometheus.Collector{
+		"Go collector":     prometheus.NewGoCollector(),
+		"Prometheus Up":    ret.PrometheusUp,
+		"Registry Metrics": ret.RegistryMetrics,
+		"Errors":           ret.Errors,
+		"Rules":            ret.Rules,
+	} {
+		if err := ret.Registry.Register(collector); err != nil {
+			return nil, fmt.Errorf("during registration of %q: %v", collectorName, err)
+		}
+	}
+
+	return ret, nil
+}
+
+func (m *ServiceMetrics) Run(port uint16) {
+	go func() {
+		mux := http.NewServeMux()
+		mux.Handle("/metrics", promhttp.Handler())
+		klog.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", port), mux))
+	}()
 }