Add pretty slog handler

go.mod

@@ -3,6 +3,7 @@ module go.gearno.de/kit
 go 1.25.0
 
 require (
+	github.com/fatih/color v1.18.0
 	github.com/go-chi/chi/v5 v5.2.3
 	github.com/jackc/pgx/v5 v5.7.6
 	github.com/prometheus/client_golang v1.23.2
@@ -29,6 +30,8 @@ require (
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
 	github.com/klauspost/compress v1.18.2 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect

go.sum

@@ -7,6 +7,8 @@ github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XL
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fatih/color v1.18.0 h1:S8gINlzdQ840/4pfAwic/ZE0djQEH3wM94VfqLTZcOM=
+github.com/fatih/color v1.18.0/go.mod h1:4FelSpRwEGDpQ12mAdzqdOukCy4u8WUtOY6lkT/6HfU=
 github.com/go-chi/chi/v5 v5.2.3 h1:WQIt9uxdsAbgIYgid+BpYc+liqQZGMHRaUwp0JUcvdE=
 github.com/go-chi/chi/v5 v5.2.3/go.mod h1:L2yAIGWB3H+phAw1NxKwWM+7eUH/lU8pOMm5hHcoops=
 github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
@@ -38,6 +40,11 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/mattn/go-colorable v0.1.13 h1:fFA4WZxdEF4tXPZVKMLwD8oUnCTTo08duU7wxecdEvA=
+github.com/mattn/go-colorable v0.1.13/go.mod h1:7S9/ev0klgBDR4GtXTXX8a3vIGJpMovkB8vQcUbaXHg=
+github.com/mattn/go-isatty v0.0.16/go.mod h1:kYGgaQfpe5nmfYZH+SKPsOc2e4SrIfOl2e/yFXSvRLM=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
@@ -93,6 +100,8 @@ golang.org/x/net v0.47.0 h1:Mx+4dIFzqraBXUugkia1OOvlD6LemFo1ALMHjrXDOhY=
 golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=
 golang.org/x/sync v0.18.0 h1:kr88TuHDroi+UVf+0hZnirlk8o8T+4MrK6mr60WkH/I=
 golang.org/x/sync v0.18.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
+golang.org/x/sys v0.0.0-20220811171246-fbc7d0a398ab/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
 golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.31.0 h1:aC8ghyu4JhP8VojJ2lEHBnochRno1sgL6nEi9WGFGMM=

log/buffer.go

@@ -0,0 +1,20 @@
+package log
+
+import (
+	"bytes"
+	"sync"
+)
+
+var bufPool = sync.Pool{
+	New: func() any {
+		return &bytes.Buffer{}
+	},
+}
+
+func getBuffer() *bytes.Buffer {
+	return bufPool.Get().(*bytes.Buffer)
+}
+
+func freeBuffer(bf *bytes.Buffer) {
+	bufPool.Put(bf)
+}

log/log.go

@@ -58,8 +58,9 @@ var (
 	LevelWarn  = slog.LevelWarn
 	LevelDebug = slog.LevelDebug
 
-	FormatJSON Format = "json"
-	FormatText Format = "text"
+	FormatJSON   Format = "json"
+	FormatPretty Format = "pretty"
+	FormatText   Format = "text"
 )
 
 // WithLevel sets the logging level for the Logger.
@@ -166,6 +167,13 @@ func NewLogger(options ...Option) *Logger {
 
 	var handler slog.Handler
 	switch l.format {
+	case FormatPretty:
+		handler = NewPrettyHandler(
+			l.output,
+			&slog.HandlerOptions{
+				Level: l.level,
+			},
+		)
 	case FormatText:
 		handler = slog.NewTextHandler(
 			l.output,

log/pretty_handler.go

@@ -0,0 +1,152 @@
+package log
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"runtime"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/fatih/color"
+)
+
+// Handler is a colored slog handler.
+type PrettyHandler struct {
+	groups []string
+	attrs  []slog.Attr
+
+	opts slog.HandlerOptions
+
+	mu  *sync.Mutex
+	out io.Writer
+}
+
+var LevelTags = map[slog.Level]string{
+	slog.LevelDebug: color.New(color.FgWhite, color.Bold).Sprint("DEBUG"),
+	slog.LevelInfo:  color.New(color.FgBlue, color.Bold).Sprint("INFO"),
+	slog.LevelWarn:  color.New(color.FgYellow, color.Bold).Sprint("WARN"),
+	slog.LevelError: color.New(color.FgRed, color.Bold).Sprint("ERROR"),
+}
+
+// NewHandler creates a new [Handler] with the specified options. If opts is nil, uses [DefaultOptions].
+func NewPrettyHandler(out io.Writer, opts *slog.HandlerOptions) *PrettyHandler {
+	h := &PrettyHandler{out: out, mu: &sync.Mutex{}}
+	if opts == nil {
+		opts = &slog.HandlerOptions{}
+	}
+	h.opts = *opts
+
+	return h
+}
+
+func (h *PrettyHandler) clone() *PrettyHandler {
+	return &PrettyHandler{
+		groups: h.groups,
+		attrs:  h.attrs,
+		opts:   h.opts,
+		mu:     h.mu,
+		out:    h.out,
+	}
+}
+
+// Enabled implements slog.Handler.Enabled .
+func (h *PrettyHandler) Enabled(_ context.Context, level slog.Level) bool {
+	return level >= h.opts.Level.Level()
+}
+
+// Handle implements slog.Handler.Handle .
+func (h *PrettyHandler) Handle(_ context.Context, r slog.Record) error {
+	bf := getBuffer()
+	bf.Reset()
+
+	fmt.Fprint(bf, color.New(color.Faint).Sprint(r.Time.Format(time.RFC3339)))
+	fmt.Fprint(bf, " ")
+
+	fmt.Fprint(bf, LevelTags[r.Level])
+	fmt.Fprint(bf, " ")
+
+	// we need the attributes here, as we can print a longer string if there are no attributes
+	stacktrace := ""
+	name := ""
+	var attrs []slog.Attr
+	attrs = append(attrs, h.attrs...)
+	r.Attrs(func(a slog.Attr) bool {
+		if a.Key == "stack" {
+			stacktrace = a.Value.String()
+			return true
+		}
+		if a.Key == "name" {
+			name = a.Value.String()
+			return true
+		}
+		attrs = append(attrs, a)
+		return true
+	})
+
+	if name != "" {
+		fmt.Fprint(bf, color.New(color.Faint, color.Bold).Sprint(name))
+		fmt.Fprint(bf, " ")
+	}
+
+	if stacktrace != "" {
+		if r.PC != 0 {
+			f, _ := runtime.CallersFrames([]uintptr{r.PC}).Next()
+
+			filename := f.File
+			lineStr := fmt.Sprintf(":%d", f.Line)
+			formatted := fmt.Sprintf("%s ", filename+lineStr)
+			fmt.Fprint(bf, formatted)
+		}
+	}
+
+	fmt.Fprint(bf, color.New(color.FgHiWhite).Sprint(r.Message))
+
+	for _, a := range attrs {
+		fmt.Fprint(bf, " ")
+		for i, g := range h.groups {
+			fmt.Fprint(bf, color.New(color.FgWhite).Sprint(g))
+			if i != len(h.groups) {
+				fmt.Fprint(bf, color.New(color.FgWhite).Sprint("."))
+			}
+		}
+
+		value := color.New(color.FgWhite).Sprint(a.Value.String())
+		if strings.Contains(a.Key, "err") {
+			fmt.Fprint(bf, color.New(color.FgRed).Sprintf("%s=", a.Key)+value)
+		} else {
+			fmt.Fprint(bf, color.New(color.Faint).Sprintf("%s=", a.Key)+value)
+		}
+	}
+
+	if stacktrace != "" {
+		fmt.Fprint(bf, "\n")
+		fmt.Fprint(bf, stacktrace)
+	}
+
+	fmt.Fprint(bf, "\n")
+
+	h.mu.Lock()
+	_, err := io.Copy(h.out, bf)
+	h.mu.Unlock()
+
+	freeBuffer(bf)
+
+	return err
+}
+
+// WithGroup implements slog.Handler.WithGroup .
+func (h *PrettyHandler) WithGroup(name string) slog.Handler {
+	h2 := h.clone()
+	h2.groups = append(h2.groups, name)
+	return h2
+}
+
+// WithAttrs implements slog.Handler.WithAttrs .
+func (h *PrettyHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	h2 := h.clone()
+	h2.attrs = append(h2.attrs, attrs...)
+	return h2
+}