♻ feat(logging): add log level configuration and improve error

handling

Author: nmdra

Dockerfile

@@ -2,4 +2,6 @@ FROM gcr.io/distroless/static:nonroot
 
 COPY semantic-search-api /semantic-search-api 
 
+ENV LOG_LEVEL=warn
+
 ENTRYPOINT [ "/semantic-search-api" ]

cmd/main.go

@@ -21,21 +21,26 @@ import (
 )
 
 type config struct {
-	port    int
-	apiKey  string
-	migrate bool
-	db      struct {
+	port     int
+	apiKey   string
+	migrate  bool
+	logLevel string
+	db       struct {
 		dsn   string
 		redis string
 	}
 }
 
 func main() {
 	cfg := loadConfig()
-	logger := setupLogger()
+	logger := setupLogger(cfg.logLevel)
 
 	if cfg.migrate {
-		runMigrations(cfg, logger)
+		err := runMigrations(cfg, logger)
+		if err != nil {
+			logger.Error("Migration failed", "error", err)
+			os.Exit(1)
+		}
 		return
 	}
 
@@ -45,11 +50,50 @@ func main() {
 	}
 
 	ctx := context.Background()
-	dbpool := connectToPostgres(ctx, cfg, logger)
+
+	dbpool, err := connectToPostgres(ctx, cfg, logger)
+	if err != nil {
+		logger.Error("Database connection failed", "error", err)
+		os.Exit(1)
+	}
 	defer dbpool.Close()
 
-	embedder := setupEmbedder(ctx, cfg, logger)
-	startServer(cfg, logger, dbpool, embedder)
+	embedder, err := newEmbedder(ctx, cfg, logger)
+	if err != nil {
+		logger.Error("Failed to setup embedder", "error", err)
+		os.Exit(1)
+	}
+
+	repo := repository.New(dbpool)
+	bookService := &service.BookService{
+		Embedder:   embedder,
+		Repository: repo,
+		Logger:     logger,
+	}
+	bookHandler := &api.BookHandler{
+		Service: bookService,
+	}
+
+	e := echo.New()
+	e.HideBanner = true
+
+	e.Use(middleware.Logger())
+	e.Use(middleware.Recover())
+	e.Use(middleware.TimeoutWithConfig(middleware.TimeoutConfig{
+		Timeout:      5 * time.Second,
+		ErrorMessage: "Request timed out.",
+		OnTimeoutRouteErrorHandler: func(err error, c echo.Context) {
+			logger.Warn("Timeout on route", "path", c.Path(), "error", err)
+		},
+	}))
+
+	e.GET("/ping", func(c echo.Context) error {
+		return c.String(200, "pong")
+	})
+	e.GET("/search", bookHandler.SearchBooks)
+	e.POST("/books", bookHandler.AddBook)
+
+	e.Logger.Fatal(e.Start(fmt.Sprintf(":%d", cfg.port)))
 }
 
 func loadConfig() config {
@@ -76,82 +120,75 @@ Flags:
 	flag.StringVar(&cfg.db.dsn, "db-dsn", defaultDSN, "PostgreSQL DSN (or set DATABASE_URL env)")
 	flag.StringVar(&cfg.db.redis, "redis", defaultRedisURL, "Redis URL (optional, or set REDIS_URL env)")
 	flag.BoolVar(&cfg.migrate, "migrate", false, "Run DB migrations and exit")
+	flag.StringVar(&cfg.logLevel, "loglevel", "info", "Log level (debug|info|warn|error)")
 
 	flag.Parse()
+
+	if cfg.db.dsn == "" {
+		fmt.Fprintln(os.Stderr, "Error: --db-dsn is required")
+		os.Exit(1)
+	}
+
+	if cfg.apiKey == "" {
+		fmt.Fprintln(os.Stderr, "Error: --apikey is required")
+		os.Exit(1)
+	}
+
 	return cfg
 }
 
-func setupLogger() *slog.Logger {
-	return slog.New(tint.NewHandler(os.Stdout, &tint.Options{
-		Level: slog.LevelInfo,
-	}))
+func setupLogger(levelStr string) *slog.Logger {
+	level := slog.LevelInfo
+
+	switch levelStr {
+	case "debug":
+		level = slog.LevelDebug
+	case "info":
+		level = slog.LevelInfo
+	case "warn", "warning":
+		level = slog.LevelWarn
+	case "error":
+		level = slog.LevelError
+	default:
+		fmt.Fprintf(os.Stderr, "invalid log level %q, defaulting to info\n", levelStr)
+	}
+
+	handler := tint.NewHandler(os.Stdout, &tint.Options{
+		Level: level,
+	})
+	return slog.New(handler)
 }
 
-func runMigrations(cfg config, logger *slog.Logger) {
+func runMigrations(cfg config, logger *slog.Logger) error {
 	if err := db.RunMigrations(cfg.db.dsn, logger); err != nil {
-		logger.Error("Migration failed", "error", err)
-		os.Exit(1)
+		return err
 	}
 	logger.Info("Migrations applied successfully")
+	return nil
 }
 
-func connectToPostgres(ctx context.Context, cfg config, logger *slog.Logger) *pgxpool.Pool {
+func connectToPostgres(ctx context.Context, cfg config, logger *slog.Logger) (*pgxpool.Pool, error) {
 	dbpool, err := db.NewPool(ctx, cfg.db.dsn, logger)
 	if err != nil {
-		logger.Error("Failed to connect to DB", "error", err)
-		os.Exit(1)
+		return nil, err
 	}
 	logger.Info("Connected to PostgreSQL")
-	return dbpool
+	return dbpool, nil
 }
 
-func setupEmbedder(ctx context.Context, cfg config, logger *slog.Logger) embed.Embedder {
-	baseEmbedder, err := embed.NewGeminiEmbedder(ctx, logger, cfg.apiKey)
+func newEmbedder(ctx context.Context, cfg config, logger *slog.Logger) (embed.Embedder, error) {
+	base, err := embed.NewGeminiEmbedder(ctx, logger, cfg.apiKey)
 	if err != nil {
-		logger.Error("Failed to initialize embedder", "error", err)
-		os.Exit(1)
+		return nil, err
 	}
 
 	if cfg.db.redis != "" {
 		redisClient := db.NewRedisClient(cfg.db.redis, logger)
 		return &embed.CachedEmbedder{
-			Base:   baseEmbedder,
+			Base:   base,
 			Redis:  redisClient,
 			Logger: logger,
-		}
-	}
-	return baseEmbedder
-}
-
-func startServer(cfg config, logger *slog.Logger, dbpool *pgxpool.Pool, embedder embed.Embedder) {
-	repo := repository.New(dbpool)
-	bookService := &service.BookService{
-		Embedder:   embedder,
-		Repository: repo,
-		Logger:     logger,
-	}
-	bookHandler := &api.BookHandler{
-		Service: bookService,
+		}, nil
 	}
-
-	e := echo.New()
-	e.HideBanner = true
-
-	e.Use(middleware.Logger())
-	e.Use(middleware.Recover())
-	e.Use(middleware.TimeoutWithConfig(middleware.TimeoutConfig{
-		Timeout:      5 * time.Second,
-		ErrorMessage: "Request timed out.",
-		OnTimeoutRouteErrorHandler: func(err error, c echo.Context) {
-			logger.Warn("Timeout on route", "path", c.Path(), "error", err)
-		},
-	}))
-
-	e.GET("/ping", func(c echo.Context) error {
-		return c.String(200, "pong")
-	})
-	e.GET("/search", bookHandler.SearchBooks)
-	e.POST("/books", bookHandler.AddBook)
-
-	e.Logger.Fatal(e.Start(fmt.Sprintf(":%d", cfg.port)))
+	return base, nil
 }

internal/db/db.go

@@ -35,8 +35,6 @@ func NewPool(ctx context.Context, dsn string, logger *slog.Logger) (*pgxpool.Poo
 		return nil, fmt.Errorf("failed to ping database: %w", err)
 	}
 
-	logger.Info("Successfully connected to database")
-
 	// Check if 'books' table exists
 	var exists bool
 	err = pool.QueryRow(ctx, `

internal/embed/cached_embedder.go

@@ -27,7 +27,7 @@ func (c *CachedEmbedder) Embed(ctx context.Context, input string) ([]float32, er
 	if err == nil {
 		var vec []float32
 		if err := json.Unmarshal(cached, &vec); err == nil {
-			c.Logger.Info("Embedding cache hit", "query", input)
+			c.Logger.Debug("Embedding cache hit", "query", input)
 			return vec, nil
 		}
 		c.Logger.Warn("Failed to unmarshal cached embedding", "error", err)

internal/embed/embed.go

@@ -62,6 +62,6 @@ func (g *GeminiEmbedder) Embed(ctx context.Context, input string) ([]float32, er
 	}
 
 	embedding := resp.Embeddings[0].Values
-	g.logger.Info("Embedding success", "length", len(embedding))
+	g.logger.Debug("Embedding success", "length", len(embedding))
 	return embedding, nil
 }