Moving to kube, refactoring code, using env variables only, adding metrics exporter

app/Prometheus/utils.go

@@ -0,0 +1,77 @@
+// Package prometheus provides useful functions to initialize and populate metrics
+package prometheus
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/collectors"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"net/http"
+)
+
+// Metrics structure for storing counter
+type Metrics struct {
+	ClientHTTPReqs  *prometheus.CounterVec
+	BackendHTTPReqs *prometheus.CounterVec
+}
+
+var (
+	// HTTPCounter Metrics
+	HTTPCounter = initializeHTTPReqCounter()
+	// Reg is a custom registry to have more control on metrics exported.
+	Reg = prometheus.NewRegistry()
+	// MetricsEnabled is the flag used to enable the prometheus metrics backend.
+	MetricsEnabled = false
+)
+
+// InitMetrics enable the metrics functionality if the flags is passed as an argument
+func InitMetrics(m bool) {
+	if m {
+		MetricsEnabled = true
+		initPrometheusRegistry()
+		// Define custom promhttp handler that expose just our custom registry.
+		http.Handle("/metrics", promhttp.HandlerFor(Reg, promhttp.HandlerOpts{
+			EnableOpenMetrics: true,
+			Registry:          Reg,
+		}))
+	}
+}
+
+// InitPrometheusRegistry initialize registry and counters if metrics flag pass as argument.
+func initPrometheusRegistry() {
+	// We use a custom registry to better now what metrics are exposed.
+	Reg = prometheus.NewRegistry()
+	Reg.MustRegister(HTTPCounter.ClientHTTPReqs)
+	Reg.MustRegister(HTTPCounter.BackendHTTPReqs)
+	Reg.MustRegister(collectors.NewBuildInfoCollector())
+}
+
+// IncrementClientCounterVec increments the counter with method label provided.
+func IncrementClientCounterVec(m string) {
+	HTTPCounter.ClientHTTPReqs.WithLabelValues(m).Inc()
+	return
+}
+
+// IncrementBackendCounterVec increments the counter with method label provided.
+func IncrementBackendCounterVec(m string) {
+	HTTPCounter.BackendHTTPReqs.WithLabelValues(m).Inc()
+	return
+}
+
+// InitializeHTTPReqCounter inits the httpReqs counter that will be exported.
+func initializeHTTPReqCounter() *Metrics {
+	HTTPCounters := &Metrics{
+		ClientHTTPReqs: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "client_http_requests_total",
+			Help: "How many HTTP requests processed, partitioned by HTTP method.",
+		},
+			[]string{"method"},
+		),
+		BackendHTTPReqs: prometheus.NewCounterVec(prometheus.CounterOpts{
+			Name: "backend_http_requests_total",
+			Help: "How many HTTP requests sent to backend, partitioned by HTTP method.",
+		},
+			[]string{"method"},
+		),
+	}
+	return HTTPCounters
+}