make logger configurable (#85)

config.go

@@ -22,9 +22,10 @@ import (
 //
 // To create a new Config, call [New].
 type Config struct {
+	logger     *slog.Logger
 	decodeHook mapstructure.DecodeHookFunc
-	delimiter  string
 	tagName    string
+	delimiter  string
 
 	values    map[string]any
 	providers []*provider
@@ -48,6 +49,10 @@ func New(opts ...Option) *Config {
 	for _, opt := range opts {
 		opt(option)
 	}
+	if option.logger == nil {
+		option.logger = slog.Default()
+	}
+	option.logger = option.logger.WithGroup("konf")
 	if option.delimiter == "" {
 		option.delimiter = "."
 	}
@@ -110,7 +115,7 @@ func (c *Config) Watch(ctx context.Context) error { //nolint:cyclop,funlen,gocog
 		watched = false
 	})
 	if watched {
-		slog.Warn("Config has been watched, call Watch again has no effects.")
+		c.logger.Warn("Config has been watched, call Watch again has no effects.")
 
 		return nil
 	}
@@ -133,7 +138,7 @@ func (c *Config) Watch(ctx context.Context) error { //nolint:cyclop,funlen,gocog
 					maps.Merge(values, w.values)
 				}
 				c.values = values
-				slog.DebugContext(ctx, "Configuration has been updated with change.")
+				c.logger.DebugContext(ctx, "Configuration has been updated with change.")
 
 				if len(onChanges) > 0 {
 					func() {
@@ -151,10 +156,10 @@ func (c *Config) Watch(ctx context.Context) error { //nolint:cyclop,funlen,gocog
 
 						select {
 						case <-done:
-							slog.DebugContext(ctx, "Configuration has been applied to onChanges.")
+							c.logger.DebugContext(ctx, "Configuration has been applied to onChanges.")
 						case <-ctx.Done():
 							if errors.Is(ctx.Err(), context.DeadlineExceeded) {
-								slog.WarnContext(ctx, "Configuration has not been fully applied to onChanges due to timeout."+
+								c.logger.WarnContext(ctx, "Configuration has not been fully applied to onChanges due to timeout."+
 									" Please check if the onChanges is blocking or takes too long to complete.")
 							}
 						}
@@ -201,13 +206,13 @@ func (c *Config) Watch(ctx context.Context) error { //nolint:cyclop,funlen,gocog
 					}
 					onChangesChannel <- onChanges()
 
-					slog.Info(
+					c.logger.Info(
 						"Configuration has been changed.",
 						"loader", watcher,
 					)
 				}
 
-				slog.DebugContext(ctx, "Watching configuration change.", "loader", watcher)
+				c.logger.DebugContext(ctx, "Watching configuration change.", "loader", watcher)
 				if err := watcher.Watch(ctx, onChange); err != nil {
 					errChan <- fmt.Errorf("watch configuration change: %w", err)
 					cancel()

default.go

@@ -4,7 +4,6 @@
 package konf
 
 import (
-	"log/slog"
 	"reflect"
 	"sync/atomic"
 
@@ -17,7 +16,7 @@ import (
 func Get[T any](path string) T { //nolint:ireturn
 	var value T
 	if err := Unmarshal(path, &value); err != nil {
-		slog.Warn(
+		Default().logger.Warn(
 			"Could not read config, return empty value instead.",
 			"error", err,
 			"path", path,

default_test.go

@@ -48,7 +48,7 @@ func TestGet_error(t *testing.T) {
 
 	assert.True(t, !konf.Get[bool]("config"))
 	expected := "WARN Could not read config, return empty value instead." +
-		" error=\"decode: cannot parse '' as bool: strconv.ParseBool: parsing \\\"string\\\": invalid syntax\"" +
-		" path=config type=bool\n"
+		" konf.error=\"decode: cannot parse '' as bool: strconv.ParseBool: parsing \\\"string\\\": invalid syntax\"" +
+		" konf.path=config konf.type=bool\n"
 	assert.Equal(t, expected, buf.String())
 }

option.go

@@ -3,7 +3,11 @@
 
 package konf
 
-import "github.com/go-viper/mapstructure/v2"
+import (
+	"log/slog"
+
+	"github.com/go-viper/mapstructure/v2"
+)
 
 // WithDelimiter provides the delimiter used when specifying config paths.
 // The delimiter is used to separate keys in the path.
@@ -36,6 +40,15 @@ func WithDecodeHook(decodeHook mapstructure.DecodeHookFunc) Option {
 	}
 }
 
+// WithLogger provides the slog.Logger for Config.
+//
+// By default, it uses slog.Default().
+func WithLogger(logger *slog.Logger) Option {
+	return func(options *options) {
+		options.logger = logger
+	}
+}
+
 type (
 	// Option configures a Config with specific options.
 	Option  func(*options)

provider/file/file.go

@@ -24,6 +24,7 @@ import (
 //
 // To create a new File, call [New].
 type File struct {
+	logger         *slog.Logger
 	path           string
 	unmarshal      func([]byte, any) error
 	ignoreNotExist bool
@@ -43,6 +44,10 @@ func New(path string, opts ...Option) File {
 	for _, opt := range opts {
 		opt(option)
 	}
+	if option.logger == nil {
+		option.logger = slog.Default()
+	}
+	option.logger = option.logger.WithGroup("konf.file")
 	if option.unmarshal == nil {
 		option.unmarshal = json.Unmarshal
 	}
@@ -54,7 +59,7 @@ func (f File) Load() (map[string]any, error) {
 	bytes, err := os.ReadFile(f.path)
 	if err != nil {
 		if f.ignoreNotExist && os.IsNotExist(err) {
-			slog.Warn("Config file does not exist.", "file", f.path)
+			f.logger.Warn("Config file does not exist.", "file", f.path)
 
 			return make(map[string]any), nil
 		}

provider/file/option.go

@@ -3,6 +3,8 @@
 
 package file
 
+import "log/slog"
+
 // WithUnmarshal provides the function used to parses the configuration file.
 // The unmarshal function must be able to unmarshal the file content into a map[string]any.
 //
@@ -20,6 +22,15 @@ func IgnoreFileNotExit() Option {
 	}
 }
 
+// WithLogger provides the slog.Logger for File loader.
+//
+// By default, it uses slog.Default().
+func WithLogger(logger *slog.Logger) Option {
+	return func(options *options) {
+		options.logger = logger
+	}
+}
+
 type (
 	// Option configures the a File with specific options.
 	Option  func(options *options)

provider/file/watch.go

@@ -6,7 +6,6 @@ package file
 import (
 	"context"
 	"fmt"
-	"log/slog"
 	"path/filepath"
 	"time"
 
@@ -21,7 +20,7 @@ func (f File) Watch(ctx context.Context, onChange func(map[string]any)) error {
 	}
 	defer func() {
 		if err := watcher.Close(); err != nil {
-			slog.WarnContext(ctx, "Error when closing file watcher.", "file", f.path, "error", err)
+			f.logger.WarnContext(ctx, "Error when closing file watcher.", "file", f.path, "error", err)
 		}
 	}()
 
@@ -68,12 +67,12 @@ func (f File) Watch(ctx context.Context, onChange func(map[string]any)) error {
 
 			switch {
 			case event.Has(fsnotify.Remove):
-				slog.Warn("Config file has been removed.", "file", f.path)
+				f.logger.Warn("Config file has been removed.", "file", f.path)
 				onChange(nil)
 			case event.Has(fsnotify.Create) || event.Has(fsnotify.Write):
 				values, err := f.Load()
 				if err != nil {
-					slog.WarnContext(ctx, "Error when reloading config file", "file", f.path, "error", err)
+					f.logger.WarnContext(ctx, "Error when reloading config file", "file", f.path, "error", err)
 
 					continue
 				}
@@ -85,7 +84,7 @@ func (f File) Watch(ctx context.Context, onChange func(map[string]any)) error {
 				return nil
 			}
 
-			slog.WarnContext(ctx, "Error when watching file", "file", f.path, "error", err)
+			f.logger.WarnContext(ctx, "Error when watching file", "file", f.path, "error", err)
 
 		case <-ctx.Done():
 			return nil

provider/fs/fs.go

@@ -25,6 +25,7 @@ import (
 //
 // To create a new FS, call [New].
 type FS struct {
+	logger         *slog.Logger
 	unmarshal      func([]byte, any) error
 	fs             fs.FS
 	path           string
@@ -49,6 +50,10 @@ func New(fs fs.FS, path string, opts ...Option) FS { //nolint:varnamelen
 	for _, opt := range opts {
 		opt(option)
 	}
+	if option.logger == nil {
+		option.logger = slog.Default()
+	}
+	option.logger = option.logger.WithGroup("konf.fs")
 	if option.unmarshal == nil {
 		option.unmarshal = json.Unmarshal
 	}
@@ -60,7 +65,7 @@ func (f FS) Load() (map[string]any, error) {
 	bytes, err := fs.ReadFile(f.fs, f.path)
 	if err != nil {
 		if f.ignoreNotExist && os.IsNotExist(err) {
-			slog.Warn("Config file does not exist.", "file", f.path)
+			f.logger.Warn("Config file does not exist.", "file", f.path)
 
 			return make(map[string]any), nil
 		}

provider/fs/option.go

@@ -3,6 +3,8 @@
 
 package fs
 
+import "log/slog"
+
 // WithUnmarshal provides the function used to parses the configuration file.
 // The unmarshal function must be able to unmarshal the file content into a map[string]any.
 //
@@ -20,6 +22,15 @@ func IgnoreFileNotExit() Option {
 	}
 }
 
+// WithLogger provides the slog.Logger for FS loader.
+//
+// By default, it uses slog.Default().
+func WithLogger(logger *slog.Logger) Option {
+	return func(options *options) {
+		options.logger = logger
+	}
+}
+
 type (
 	// Option configures the a FS with specific options.
 	Option  func(file *options)