change slice metrics to map metrics

example/example.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"github.com/mcuadros/go-gin-prometheus"
+	ginprometheus "github.com/mcuadros/go-gin-prometheus"
 
 	"github.com/gin-gonic/gin"
 )
@@ -28,9 +28,29 @@ func main() {
 			//	histogram, histogram_vec, summary, summary_vec
 		}
 		p := ginprometheus.NewPrometheus("gin", customMetrics)
+		// add data to custom metrics
+		m := p.MetricsList["1234"].MetricCollector.(prometheus.Counter)
+		m.Inc()
 	*/
 
-	p := ginprometheus.NewPrometheus("gin")
+	customMetrics := []*ginprometheus.Metric{
+		{
+			ID:          "1234",                // optional string
+			Name:        "test_metric",         // required string
+			Description: "Counter test metric", // required string
+			Type:        "counter",             // required string
+		},
+		{
+			ID:          "1235",                // Identifier
+			Name:        "test_metric_2",       // Metric Name
+			Description: "Summary test metric", // Help Description
+			Type:        "summary",             // type associated with prometheus collector
+		},
+		// Type Options:
+		//	counter, counter_vec, gauge, gauge_vec,
+		//	histogram, histogram_vec, summary, summary_vec
+	}
+	p := ginprometheus.NewPrometheus("gin", customMetrics)
 
 	p.Use(r)
 	r.GET("/", func(c *gin.Context) {

middleware.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"strconv"
+	"sync"
 	"time"
 
 	"github.com/gin-gonic/gin"
@@ -94,13 +95,14 @@ type Prometheus struct {
 	listenAddress string
 	Ppg           PrometheusPushGateway
 
-	MetricsList []*Metric
+	MetricsList map[string]*Metric
 	MetricsPath string
 
 	ReqCntURLLabelMappingFn RequestCounterURLLabelMappingFn
 
 	// gin.Context string to use as a prometheus URL label
 	URLLabelFromContext string
+	sync.RWMutex
 }
 
 // PrometheusPushGateway contains the configuration for pushing to a Prometheus pushgateway (optional)
@@ -123,17 +125,20 @@ type PrometheusPushGateway struct {
 
 // NewPrometheus generates a new set of metrics with a certain subsystem name
 func NewPrometheus(subsystem string, customMetricsList ...[]*Metric) *Prometheus {
-
-	var metricsList []*Metric
+	metricsList := make(map[string]*Metric)
 
 	if len(customMetricsList) > 1 {
 		panic("Too many args. NewPrometheus( string, <optional []*Metric> ).")
 	} else if len(customMetricsList) == 1 {
-		metricsList = customMetricsList[0]
+		if len(customMetricsList[0]) > 0 {
+			for _, metric := range customMetricsList[0] {
+				metricsList[metric.ID] = metric
+			}
+		}
 	}
 
 	for _, metric := range standardMetrics {
-		metricsList = append(metricsList, metric)
+		metricsList[metric.ID] = metric
 	}
 
 	p := &Prometheus{
@@ -219,6 +224,12 @@ func (p *Prometheus) getMetrics() []byte {
 	return body
 }
 
+func (p *Prometheus) GetMetric(id string) *Metric {
+	p.RLock()
+	defer p.RUnlock()
+	return p.MetricsList[id]
+}
+
 func (p *Prometheus) getPushGatewayURL() string {
 	h, _ := os.Hostname()
 	if p.Ppg.Job == "" {
@@ -229,6 +240,10 @@ func (p *Prometheus) getPushGatewayURL() string {
 
 func (p *Prometheus) sendMetricsToPushGateway(metrics []byte) {
 	req, err := http.NewRequest("POST", p.getPushGatewayURL(), bytes.NewBuffer(metrics))
+	if err != nil {
+		log.WithError(err).Errorln("Error New post request")
+		return
+	}
 	client := &http.Client{}
 	if _, err = client.Do(req); err != nil {
 		log.WithError(err).Errorln("Error sending to push gateway")
@@ -321,7 +336,6 @@ func NewMetric(m *Metric, subsystem string) prometheus.Collector {
 }
 
 func (p *Prometheus) registerMetrics(subsystem string) {
-
 	for _, metricDef := range p.MetricsList {
 		metric := NewMetric(metricDef, subsystem)
 		if err := prometheus.Register(metric); err != nil {