Implement reporting status classes in metrics (#8548)

This commit introduces a backwards compatible command line option
--report-status-classes which will enable reporting response status classes
(2xx, 3xx..) instead of status codes in exported metrics.

internal/ingress/metric/collectors/socket.go

@@ -85,7 +85,8 @@ type SocketCollector struct {
 
 	hosts sets.String
 
-	metricsPerHost bool
+	metricsPerHost      bool
+	reportStatusClasses bool
 
 	buckets HistogramBuckets
 }
@@ -110,7 +111,7 @@ var defObjectives = map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001}
 
 // NewSocketCollector creates a new SocketCollector instance using
 // the ingress watch namespace and class used by the controller
-func NewSocketCollector(pod, namespace, class string, metricsPerHost bool, buckets HistogramBuckets) (*SocketCollector, error) {
+func NewSocketCollector(pod, namespace, class string, metricsPerHost, reportStatusClasses bool, buckets HistogramBuckets) (*SocketCollector, error) {
 	socket := "/tmp/nginx/prometheus-nginx.socket"
 	// unix sockets must be unlink()ed before being used
 	_ = syscall.Unlink(socket)
@@ -139,7 +140,8 @@ func NewSocketCollector(pod, namespace, class string, metricsPerHost bool, bucke
 	sc := &SocketCollector{
 		listener: listener,
 
-		metricsPerHost: metricsPerHost,
+		metricsPerHost:      metricsPerHost,
+		reportStatusClasses: reportStatusClasses,
 
 		responseTime: prometheus.NewHistogramVec(
 			prometheus.HistogramOpts{
@@ -249,6 +251,10 @@ func (sc *SocketCollector) handleMessage(msg []byte) {
 			continue
 		}
 
+		if sc.reportStatusClasses && len(stats.Status) > 0 {
+			stats.Status = fmt.Sprintf("%cxx", stats.Status[0])
+		}
+
 		// Note these must match the order in requestTags at the top
 		requestLabels := prometheus.Labels{
 			"status":    stats.Status,