feat: Add metrics

Fixes #7.

Signed-off-by: Julien Riou <julien@riou.xyz>

src/cmd/collerd/main.go

@@ -7,6 +7,7 @@ import (
 
 	"git.riou.xyz/jriou/coller/internal"
 	"git.riou.xyz/jriou/coller/server"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 var (
@@ -75,6 +76,16 @@ func handleMain() int {
 	srv.SetIDLength(config.IDLength)
 	srv.SetPasswordLength(config.PasswordLength)
 
+	if config.EnableMetrics {
+		reg := prometheus.NewRegistry()
+		metrics, err := server.NewMetrics(logger, reg, config, db)
+		if err != nil {
+			logger.Error("could not register metrics", slog.Any("error", err))
+			return internal.RC_ERROR
+		}
+		srv.SetMetrics(metrics)
+	}
+
 	err = srv.Start()
 	if err != nil {
 		logger.Error("could not start server", slog.Any("error", err))