initial prometheus metrics support, simplfied some code

internal/metrics/http_handler.go

@@ -0,0 +1,13 @@
+package metrics
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+func NewHandler() http.Handler {
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.Handler())
+	return mux
+}

internal/metrics/http_metrics.go

@@ -0,0 +1,82 @@
+package metrics
+
+import (
+	"strings"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/yusing/go-proxy/internal/common"
+)
+
+type (
+	RouteMetrics struct {
+		HTTPReqTotal,
+		HTTP2xx3xx,
+		HTTP4xx,
+		HTTP5xx *Counter
+		HTTPReqElapsed *Gauge
+	}
+	HTTPRouteMetricLabels struct {
+		Service, Method, Host, Visitor, Path string
+	}
+)
+
+var rm RouteMetrics
+
+const (
+	routerNamespace     = "router"
+	routerHTTPSubsystem = "http"
+)
+
+func GetRouteMetrics() *RouteMetrics {
+	return &rm
+}
+
+func (lbl HTTPRouteMetricLabels) toPromLabels() prometheus.Labels {
+	return prometheus.Labels{
+		"service": lbl.Service,
+		"method":  lbl.Method,
+		"host":    lbl.Host,
+		"visitor": lbl.Visitor,
+		"path":    lbl.Path,
+	}
+}
+
+func init() {
+	if !common.PrometheusEnabled {
+		return
+	}
+	lbls := []string{"service", "method", "host", "visitor", "path"}
+	partitionsHelp := ", partitioned by " + strings.Join(lbls, ", ")
+	rm = RouteMetrics{
+		HTTPReqTotal: NewCounter(prometheus.CounterOpts{
+			Namespace: routerNamespace,
+			Subsystem: routerHTTPSubsystem,
+			Name:      "req_total",
+			Help:      "How many requests processed" + partitionsHelp,
+		}),
+		HTTP2xx3xx: NewCounter(prometheus.CounterOpts{
+			Namespace: routerNamespace,
+			Subsystem: routerHTTPSubsystem,
+			Name:      "req_ok_count",
+			Help:      "How many 2xx-3xx requests processed" + partitionsHelp,
+		}, lbls...),
+		HTTP4xx: NewCounter(prometheus.CounterOpts{
+			Namespace: routerNamespace,
+			Subsystem: routerHTTPSubsystem,
+			Name:      "req_4xx_count",
+			Help:      "How many 4xx requests processed" + partitionsHelp,
+		}, lbls...),
+		HTTP5xx: NewCounter(prometheus.CounterOpts{
+			Namespace: routerNamespace,
+			Subsystem: routerHTTPSubsystem,
+			Name:      "req_5xx_count",
+			Help:      "How many 5xx requests processed" + partitionsHelp,
+		}, lbls...),
+		HTTPReqElapsed: NewGauge(prometheus.GaugeOpts{
+			Namespace: routerNamespace,
+			Subsystem: routerHTTPSubsystem,
+			Name:      "req_elapsed_ms",
+			Help:      "How long it took to process the request" + partitionsHelp,
+		}, lbls...),
+	}
+}

internal/metrics/metric.go

@@ -0,0 +1,73 @@
+package metrics
+
+import "github.com/prometheus/client_golang/prometheus"
+
+type (
+	Counter struct {
+		collector prometheus.Counter
+		mv        *prometheus.CounterVec
+	}
+	Gauge struct {
+		collector prometheus.Gauge
+		mv        *prometheus.GaugeVec
+	}
+	Labels interface {
+		toPromLabels() prometheus.Labels
+	}
+)
+
+func NewCounter(opts prometheus.CounterOpts, labels ...string) *Counter {
+	m := &Counter{
+		mv: prometheus.NewCounterVec(opts, labels),
+	}
+	if len(labels) == 0 {
+		m.collector = m.mv.WithLabelValues()
+		m.collector.Add(0)
+	}
+	prometheus.MustRegister(m)
+	return m
+}
+
+func NewGauge(opts prometheus.GaugeOpts, labels ...string) *Gauge {
+	m := &Gauge{
+		mv: prometheus.NewGaugeVec(opts, labels),
+	}
+	if len(labels) == 0 {
+		m.collector = m.mv.WithLabelValues()
+		m.collector.Set(0)
+	}
+	prometheus.MustRegister(m)
+	return m
+}
+
+func (c *Counter) Collect(ch chan<- prometheus.Metric) {
+	c.mv.Collect(ch)
+}
+
+func (c *Counter) Describe(ch chan<- *prometheus.Desc) {
+	c.mv.Describe(ch)
+}
+
+func (c *Counter) Inc() {
+	c.collector.Inc()
+}
+
+func (c *Counter) With(l Labels) prometheus.Counter {
+	return c.mv.With(l.toPromLabels())
+}
+
+func (g *Gauge) Collect(ch chan<- prometheus.Metric) {
+	g.mv.Collect(ch)
+}
+
+func (g *Gauge) Describe(ch chan<- *prometheus.Desc) {
+	g.mv.Describe(ch)
+}
+
+func (g *Gauge) Set(v float64) {
+	g.collector.Set(v)
+}
+
+func (g *Gauge) With(l Labels) prometheus.Gauge {
+	return g.mv.With(l.toPromLabels())
+}

internal/metrics/router_metrics.go

@@ -0,0 +1,20 @@
+package metrics
+
+import "github.com/prometheus/client_golang/prometheus"
+
+func InitRouterMetrics(getRPsCount func() int, getStreamsCount func() int) {
+	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: "entrypoint",
+		Name:      "num_reverse_proxies",
+		Help:      "The number of reverse proxies",
+	}, func() float64 {
+		return float64(getRPsCount())
+	}))
+	prometheus.MustRegister(prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: "entrypoint",
+		Name:      "num_streams",
+		Help:      "The number of streams",
+	}, func() float64 {
+		return float64(getStreamsCount())
+	}))
+}