refactor(logging): move logging setup to internal/logging

Moves logging configuration and setup to a dedicated package. Updates Config struct to use nested LoggingConfig. Updates main.go to use the new logging package.

cmd/app/main.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/placeholder/golang-template/internal/config"
+	"github.com/placeholder/golang-template/internal/logging"
 )
 
 func main() {
@@ -27,11 +28,9 @@ func main() {
 	}
 
 	// Setup Logger
-	opts := &slog.HandlerOptions{
+	logging.Configure(logging.Config{
-		Level: config.ParseLogLevel(cfg.LogLevel),
+		Level: cfg.Logging.Level,
-	}
+	})
-	logger := slog.New(slog.NewJSONHandler(os.Stdout, opts))
-	slog.SetDefault(logger)
 
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()

config/config.yaml

@@ -1,7 +1,12 @@
 # Application Configuration
 # This file contains the default configuration for the application.
 # Values can be overridden by environment variables with the prefix "APP_".
-# Example: APP_LOG_LEVEL=debug
+# Example: APP_LOGGING_LEVEL=debug
 
-# Log Level: debug, info, warn, error
+logging:
-log_level: "info"
+  # Log Level: debug, info, warn, error
+  level: "info"
+
+server:
+  host: "localhost"
+  port: 8080

internal/config/config.go

@@ -2,7 +2,6 @@ package config
 
 import (
 	"fmt"
-	"log/slog"
 	"os"
 	"reflect"
 	"strconv"
@@ -14,10 +13,15 @@ import (
 
 // Config holds the application configuration.
 type Config struct {
-	LogLevel string       `yaml:"log_level"`
+	Logging LoggingConfig `yaml:"logging"`
 	Server  ServerConfig  `yaml:"server"`
 }
 
+// LoggingConfig holds logging-specific configuration.
+type LoggingConfig struct {
+	Level string `yaml:"level"`
+}
+
 // ServerConfig holds server-specific configuration.
 type ServerConfig struct {
 	Host string `yaml:"host"`
@@ -50,22 +54,6 @@ func Load(configPath string, envPrefix string) (*Config, error) {
 	return cfg, nil
 }
 
-// ParseLogLevel converts a string log level to a slog.Level.
-func ParseLogLevel(level string) slog.Level {
-	switch strings.ToLower(level) {
-	case "debug":
-		return slog.LevelDebug
-	case "info":
-		return slog.LevelInfo
-	case "warn":
-		return slog.LevelWarn
-	case "error":
-		return slog.LevelError
-	default:
-		return slog.LevelInfo
-	}
-}
-
 // overrideFromEnv uses reflection to traverse the struct and update fields from env vars.
 func overrideFromEnv(cfg interface{}, prefix string) error {
 	v := reflect.ValueOf(cfg)

internal/config/config_test.go

@@ -1,7 +1,6 @@
 package config
 
 import (
-	"log/slog"
 	"os"
 	"path/filepath"
 	"testing"
@@ -13,7 +12,8 @@ func TestLoad(t *testing.T) {
 	configFile := filepath.Join(tmpDir, "config.yaml")
 	
 	yamlContent := []byte(`
-log_level: "info"
+logging:
+  level: "info"
 server:
   host: "localhost"
   port: 8080
@@ -27,8 +27,8 @@ server:
 		if err != nil {
 			t.Fatalf("Load() error = %v", err)
 		}
-		if cfg.LogLevel != "info" {
+		if cfg.Logging.Level != "info" {
-			t.Errorf("expected LogLevel 'info', got '%s'", cfg.LogLevel)
+			t.Errorf("expected Logging.Level 'info', got '%s'", cfg.Logging.Level)
 		}
 		if cfg.Server.Host != "localhost" {
 			t.Errorf("expected Server.Host 'localhost', got '%s'", cfg.Server.Host)
@@ -39,11 +39,11 @@ server:
 	})
 
 	t.Run("Override from Env", func(t *testing.T) {
-		os.Setenv("TEST_LOG_LEVEL", "debug")
+		os.Setenv("TEST_LOGGING_LEVEL", "debug")
 		os.Setenv("TEST_SERVER_PORT", "9090")
 		os.Setenv("TEST_SERVER_HOST", "0.0.0.0")
 		defer func() {
-			os.Unsetenv("TEST_LOG_LEVEL")
+			os.Unsetenv("TEST_LOGGING_LEVEL")
 			os.Unsetenv("TEST_SERVER_PORT")
 			os.Unsetenv("TEST_SERVER_HOST")
 		}()
@@ -52,8 +52,8 @@ server:
 		if err != nil {
 			t.Fatalf("Load() error = %v", err)
 		}
-		if cfg.LogLevel != "debug" {
+		if cfg.Logging.Level != "debug" {
-			t.Errorf("expected LogLevel 'debug', got '%s'", cfg.LogLevel)
+			t.Errorf("expected Logging.Level 'debug', got '%s'", cfg.Logging.Level)
 		}
 		if cfg.Server.Port != 9090 {
 			t.Errorf("expected Server.Port 9090, got %d", cfg.Server.Port)
@@ -63,26 +63,3 @@ server:
 		}
 	})
 }
-
-func TestParseLogLevel(t *testing.T) {
-	tests := []struct {
-		input    string
-		expected slog.Level
-	}{
-		{"debug", slog.LevelDebug},
-		{"DEBUG", slog.LevelDebug},
-		{"info", slog.LevelInfo},
-		{"warn", slog.LevelWarn},
-		{"error", slog.LevelError},
-		{"unknown", slog.LevelInfo},
-		{"", slog.LevelInfo},
-	}
-
-	for _, tt := range tests {
-		t.Run(tt.input, func(t *testing.T) {
-			if got := ParseLogLevel(tt.input); got != tt.expected {
-				t.Errorf("ParseLogLevel(%q) = %v, want %v", tt.input, got, tt.expected)
-			}
-		})
-	}
-}

internal/logging/logging.go

@@ -0,0 +1,37 @@
+package logging
+
+import (
+	"log/slog"
+	"os"
+	"strings"
+)
+
+// Config holds the logging configuration.
+type Config struct {
+	Level string `yaml:"level"`
+}
+
+// Configure sets up the global logger based on the provided configuration.
+func Configure(cfg Config) *slog.Logger {
+	opts := &slog.HandlerOptions{
+		Level: parseLogLevel(cfg.Level),
+	}
+	logger := slog.New(slog.NewJSONHandler(os.Stdout, opts))
+	slog.SetDefault(logger)
+	return logger
+}
+
+func parseLogLevel(level string) slog.Level {
+	switch strings.ToLower(level) {
+	case "debug":
+		return slog.LevelDebug
+	case "info":
+		return slog.LevelInfo
+	case "warn":
+		return slog.LevelWarn
+	case "error":
+		return slog.LevelError
+	default:
+		return slog.LevelInfo
+	}
+}

internal/logging/logging_test.go

@@ -0,0 +1,37 @@
+package logging
+
+import (
+	"log/slog"
+	"testing"
+)
+
+func TestParseLogLevel(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected slog.Level
+	}{
+		{"debug", slog.LevelDebug},
+		{"DEBUG", slog.LevelDebug},
+		{"info", slog.LevelInfo},
+		{"warn", slog.LevelWarn},
+		{"error", slog.LevelError},
+		{"unknown", slog.LevelInfo},
+		{"", slog.LevelInfo},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			if got := parseLogLevel(tt.input); got != tt.expected {
+				t.Errorf("parseLogLevel(%q) = %v, want %v", tt.input, got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestConfigure(t *testing.T) {
+	cfg := Config{Level: "debug"}
+	logger := Configure(cfg)
+	if logger == nil {
+		t.Error("Configure() returned nil")
+	}
+}