logger: add Fatal finalizers

* closes #222

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

logger/options.go

@@ -52,6 +52,12 @@ type Options struct {
 	AddStacktrace bool
 	// DedupKeys deduplicate keys in log output
 	DedupKeys bool
+	// FatalFinalizers runs in order in [logger.Fatal] method
+	FatalFinalizers []func(context.Context)
+}
+
+var DefaultFatalFinalizer = func(ctx context.Context) {
+	os.Exit(1)
 }
 
 // NewOptions creates new options struct
@@ -65,6 +71,7 @@ func NewOptions(opts ...Option) Options {
 		AddSource:        true,
 		TimeFunc:         time.Now,
 		Meter:            meter.DefaultMeter,
+		FatalFinalizers:  []func(context.Context){DefaultFatalFinalizer},
 	}
 
 	WithMicroKeys()(&options)
@@ -76,6 +83,13 @@ func NewOptions(opts ...Option) Options {
 	return options
 }
 
+// WithFatalFinalizers set logger.Fatal finalizers
+func WithFatalFinalizers(fncs []func(context.Context)) Option {
+	return func(o *Options) {
+		o.FatalFinalizers = fncs
+	}
+}
+
 // WithContextAttrFuncs appends default funcs for the context attrs filler
 func WithContextAttrFuncs(fncs ...ContextAttrFunc) Option {
 	return func(o *Options) {

logger/slog/slog.go

@@ -4,14 +4,12 @@ import (
 	"context"
 	"io"
 	"log/slog"
-	"os"
 	"reflect"
 	"regexp"
 	"runtime"
 	"strconv"
 	"sync"
 	"sync/atomic"
-	"time"
 
 	"go.unistack.org/micro/v4/logger"
 	"go.unistack.org/micro/v4/semconv"
@@ -234,8 +232,9 @@ func (s *slogLogger) Fatal(ctx context.Context, msg string, attrs ...interface{}
 	if closer, ok := s.opts.Out.(io.Closer); ok {
 		closer.Close()
 	}
-	time.Sleep(1 * time.Second)
-	os.Exit(1)
+	for _, fn := range s.opts.FatalFinalizers {
+		fn(ctx)
+	}
 }
 
 func (s *slogLogger) Warn(ctx context.Context, msg string, attrs ...interface{}) {