update environment configuration for local development, enhance database initialization, and improve Nginx routing for admin access

backend/chat/src/main.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/gorilla/websocket"
 	"github.com/redis/go-redis/v9"
+	"gorm.io/driver/postgres"
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"
 )
@@ -56,11 +57,25 @@ type Presence struct {
 
 // initRedis initializes Redis for presence, rate limiting, and pub/sub (ADR-007)
 func initRedis() {
-	redisClient = redis.NewClient(&redis.Options{
-		Addr:     os.Getenv("REDIS_URL"),
-		Password: "",
-		DB:       0,
-	})
+	redisAddress := os.Getenv("REDIS_URL")
+	if redisAddress == "" {
+		redisAddress = "redis:6379"
+	}
+
+	var options *redis.Options
+	var err error
+	if strings.Contains(redisAddress, "://") {
+		options, err = redis.ParseURL(redisAddress)
+		if err != nil {
+			log.Printf("Redis configuration warning: %v (rate limiting and presence will be disabled)", err)
+			redisClient = nil
+			return
+		}
+	} else {
+		options = &redis.Options{Addr: redisAddress}
+	}
+
+	redisClient = redis.NewClient(options)
 	if err := redisClient.Ping(context.Background()).Err(); err != nil {
 		log.Printf("Redis connection warning: %v (rate limiting and presence will be disabled)", err)
 		redisClient = nil
@@ -72,12 +87,31 @@ func initRedis() {
 // initDB initializes SQLite for message history and moderation audit log (ADR-006)
 func initDB() {
 	var err error
-	db, err = gorm.Open(sqlite.Open("chat.db"), &gorm.Config{})
-	if err != nil {
-		log.Fatal("Failed to connect to SQLite:", err)
+	databaseURL := strings.TrimSpace(os.Getenv("DATABASE_URL"))
+	driverName := "sqlite"
+
+	switch {
+	case databaseURL == "":
+		db, err = gorm.Open(sqlite.Open("chat.db"), &gorm.Config{})
+	case strings.HasPrefix(databaseURL, "sqlite://"):
+		sqlitePath := strings.TrimPrefix(databaseURL, "sqlite://")
+		if sqlitePath == "" {
+			sqlitePath = "chat.db"
+		}
+		db, err = gorm.Open(sqlite.Open(sqlitePath), &gorm.Config{})
+	case strings.HasPrefix(databaseURL, "postgres://") || strings.HasPrefix(databaseURL, "postgresql://"):
+		driverName = "postgres"
+		db, err = gorm.Open(postgres.Open(databaseURL), &gorm.Config{})
+	default:
+		log.Fatalf("Unsupported DATABASE_URL scheme: %s", databaseURL)
 	}
+
+	if err != nil {
+		log.Fatalf("Failed to connect to %s database: %v", driverName, err)
+	}
+
 	db.AutoMigrate(&Message{}, &ModerationLog{})
-	log.Println("SQLite database initialized (chat history and moderation log)")
+	log.Printf("%s database initialized (chat history and moderation log)", strings.Title(driverName))
 }
 
 // broadcast sends a message to all connected clients in a room and saves to DB
@@ -110,7 +144,7 @@ func handleConnection(w http.ResponseWriter, r *http.Request) {
 	// Announce presence (ADR-007)
 	username := r.URL.Query().Get("username")
 	room := r.URL.Query().Get("room")
-	if username != "" && room != "" {
+	if redisClient != nil && username != "" && room != "" {
 		redisClient.Set(context.Background(), fmt.Sprintf("presence:%s:%s", room, username), "online", 60*time.Second)
 		broadcast(Message{Room: room, Username: "system", Text: username + " joined " + room, Type: "system"})
 	}
@@ -119,7 +153,7 @@ func handleConnection(w http.ResponseWriter, r *http.Request) {
 		mutex.Lock()
 		delete(clients, conn)
 		mutex.Unlock()
-		if username != "" && room != "" {
+		if redisClient != nil && username != "" && room != "" {
 			redisClient.Del(context.Background(), fmt.Sprintf("presence:%s:%s", room, username))
 			broadcast(Message{Room: room, Username: "system", Text: username + " left " + room, Type: "system"})
 		}
@@ -230,6 +264,6 @@ func main() {
 		port = "3000"
 	}
 
-	log.Printf("Chat Backend starting on :%s (WebSocket at /ws, health at /health, SQLite persistence enabled)", port)
+	log.Printf("Chat Backend starting on :%s (WebSocket at /ws, health at /health, database persistence enabled)", port)
 	log.Fatal(http.ListenAndServe(":"+port, nil))
 }