feat: add metrics support

internal/metrics/metrics.go

@@ -0,0 +1,65 @@
+package metrics
+
+import (
+	"fmt"
+	"net/http"
+	"sync"
+)
+
+var (
+	metricsMu sync.RWMutex
+	metrics   = make(map[string]int64)
+)
+
+func IncBan(service string) {
+	metricsMu.Lock()
+	metrics["ban_count"]++
+	metrics[service+"_bans"]++
+	metricsMu.Unlock()
+}
+
+func IncUnban(service string) {
+	metricsMu.Lock()
+	metrics["unban_count"]++
+	metrics[service+"_unbans"]++
+	metricsMu.Unlock()
+}
+
+func IncRuleMatched(rule_name string) {
+	metricsMu.Lock()
+	metrics[rule_name+"_rule_matched"]++
+	metricsMu.Unlock()
+}
+
+func IncLogParsed() {
+	metricsMu.Lock()
+	metrics["log_parsed"]++
+	metricsMu.Unlock()
+}
+
+func MetricsHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+		metricsMu.RLock()
+		snapshot := make(map[string]int64, len(metrics))
+		for k, v := range metrics {
+			snapshot[k] = v
+		}
+		metricsMu.RUnlock()
+
+		w.Header().Set("Content-Type", "text/plain; version=0.0.4")
+
+		for name, value := range snapshot {
+			metricName := name + "_total"
+			fmt.Fprintf(w, "# TYPE %s counter\n", metricName)
+			fmt.Fprintf(w, "%s %d\n", metricName, value)
+		}
+	})
+}
+func StartMetricsServer(port int) {
+	http.Handle("/metrics", MetricsHandler())
+	addr := fmt.Sprintf(":%d", port)
+	if err := http.ListenAndServe(addr, nil); err != nil {
+	}
+}
+