Add package slogd

Signed-off-by: Jan Tytgat <jan.tytgat@corelayer.eu>

pkg/slogd/slogd.go

@@ -0,0 +1,140 @@
+package slogd
+
+import (
+	"context"
+	"log/slog"
+	"sync"
+
+	slogformatter "github.com/samber/slog-formatter"
+	slogmulti "github.com/samber/slog-multi"
+)
+
+const (
+	HandlerText     string = "text"
+	HandlerJSON     string = "json"
+	handlerDisabled string = "disabled"
+)
+
+const (
+	FlowFanOut Flow = iota
+	FlowPipeline
+	FlowRouting
+	FlowFailOver
+	FlowLoadBalancing
+)
+
+type Flow int
+
+var (
+	ctxKey = contextKey{}
+)
+var (
+	handlers      = make(map[string]slog.Handler)
+	activeHandler string
+	level         = new(slog.LevelVar)
+	formatters    []slogformatter.Formatter
+	middlewares   []slogmulti.Middleware
+	source        bool
+	logger        *slog.Logger
+	mux           = &sync.Mutex{}
+)
+
+func ActiveHandler() string {
+	mux.Lock()
+	defer mux.Unlock()
+	return activeHandler
+}
+
+func Key() contextKey {
+	return ctxKey
+}
+
+func Disable() {
+	UseHandler(handlerDisabled)
+}
+
+func FromContext(ctx context.Context) *slog.Logger {
+	if l, ok := ctx.Value(Key()).(*slog.Logger); ok {
+		return l
+	}
+	return Logger()
+}
+
+func HandlerOptions() *slog.HandlerOptions {
+	return &slog.HandlerOptions{
+		AddSource:   source,
+		Level:       level,
+		ReplaceAttr: ReplaceAttrs,
+	}
+}
+
+func Init(l slog.Level, addSource bool) {
+	level.Set(l)
+	source = addSource
+}
+
+func Logger() *slog.Logger {
+	mux.Lock()
+	defer mux.Unlock()
+
+	if logger == nil {
+		logger = slog.New(handlers[handlerDisabled])
+	}
+	return logger
+}
+
+func SetLevel(l slog.Level) {
+	mux.Lock()
+	defer mux.Unlock()
+	level.Set(l)
+}
+
+func RegisterFormatter(f slogformatter.Formatter) {
+	mux.Lock()
+	defer mux.Unlock()
+	formatters = append(formatters, f)
+}
+
+func RegisterMiddleware(h slogmulti.Middleware) {
+	mux.Lock()
+	defer mux.Unlock()
+	middlewares = append(middlewares, h)
+}
+
+func RegisterSink(name string, h slog.Handler, activate bool) {
+	mux.Lock()
+	handlers[name] = h
+	mux.Unlock()
+
+	if activate {
+		UseHandler(name)
+	}
+}
+
+func UseHandler(name string) {
+	mux.Lock()
+	defer mux.Unlock()
+	if _, ok := handlers[name]; !ok {
+		Logger().LogAttrs(context.Background(), LevelError, "could not find handler", slog.String("name", name))
+		return
+	}
+
+	formatterPipe := slogformatter.NewFormatterMiddleware(formatters...)
+	pipe := slogmulti.Pipe(middlewares...).Pipe(formatterPipe)
+	handler := slogmulti.Fanout(handlers[name])
+
+	logger = slog.New(pipe.Handler(handler))
+	activeHandler = name
+}
+
+func WithContext(ctx context.Context) context.Context {
+	return context.WithValue(ctx, Key(), Logger())
+}
+
+func init() {
+	// RegisterFormatter(LevelFormatter())
+	// RegisterMiddleware(NewLevelMiddleware())
+	registerDisabledHandler(true)
+}
+
+type contextKey struct{}