chore: add go config and logging layer

backend/cmd/api/main.go

@@ -3,17 +3,25 @@ package main
 import (
 	"context"
 	"errors"
-	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
 	"syscall"
 	"time"
+
+	"forgejo.digital-droplets.de/philschlo/proxui/platform/config"
+	"forgejo.digital-droplets.de/philschlo/proxui/platform/logging"
 )
 
 func main() {
-	addr := getenv("BACKEND_ADDR", ":8080")
-	logger := slog.New(slog.NewJSONHandler(os.Stdout, nil))
+	cfg, err := config.Load()
+	if err != nil {
+		logger := logging.New("backend", "unknown", 0)
+		logger.Error("failed to load config", "error", err)
+		os.Exit(1)
+	}
+
+	logger := logging.New("backend", cfg.AppEnv, cfg.LogLevel)
 
 	mux := http.NewServeMux()
 	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
@@ -22,7 +30,7 @@ func main() {
 	})
 
 	server := &http.Server{
-		Addr:              addr,
+		Addr:              cfg.BackendAddr,
 		Handler:           mux,
 		ReadHeaderTimeout: 5 * time.Second,
 	}
@@ -31,7 +39,7 @@ func main() {
 	defer stop()
 
 	go func() {
-		logger.Info("backend listening", "addr", addr)
+		logger.Info("backend listening", "addr", cfg.BackendAddr)
 		if err := server.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 			logger.Error("backend failed", "error", err)
 			os.Exit(1)
@@ -47,10 +55,3 @@ func main() {
 		os.Exit(1)
 	}
 }
-
-func getenv(key, fallback string) string {
-	if value := os.Getenv(key); value != "" {
-		return value
-	}
-	return fallback
-}