fix(telemetry): filter otel logs by log level (#1773)

app/common/telemetry.go

@@ -102,7 +102,10 @@ func NewLogger(conf config.LogTelemetryConfig, res *resource.Resource, loggerPro
 			).Handler(conf.NewHandler(os.Stdout)),
 
 			// Otel logger
-			realotelslog.NewHandler(metadata.OpenTelemetryName, realotelslog.WithLoggerProvider(loggerProvider)),
+			NewLevelHandler(
+				realotelslog.NewHandler(metadata.OpenTelemetryName, realotelslog.WithLoggerProvider(loggerProvider)),
+				conf.Level,
+			),
 		)),
 	)
 }
@@ -220,3 +223,37 @@ func NewTelemetryRouterHook(meterProvider metric.MeterProvider, tracerProvider t
 		})
 	}
 }
+
+// Compile-time check LevelHandler implements slog.Handler.
+var _ slog.Handler = (*LevelHandler)(nil)
+
+// NewLevelHandler returns a new LevelHandler.
+func NewLevelHandler(handler slog.Handler, level slog.Leveler) *LevelHandler {
+	return &LevelHandler{
+		handler: handler,
+		level:   level,
+	}
+}
+
+// LevelHandler is a slog.Handler that filters log records based on the log level.
+type LevelHandler struct {
+	handler slog.Handler
+	level   slog.Leveler
+}
+
+func (h *LevelHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	// The higher the level, the more important or severe the event.
+	return level >= h.level.Level() && h.handler.Enabled(ctx, level)
+}
+
+func (h *LevelHandler) WithGroup(name string) slog.Handler {
+	return h.handler.WithGroup(name)
+}
+
+func (h *LevelHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return h.handler.WithAttrs(attrs)
+}
+
+func (h *LevelHandler) Handle(ctx context.Context, record slog.Record) error {
+	return h.handler.Handle(ctx, record)
+}

app/common/telemetry_test.go

@@ -0,0 +1,46 @@
+package common
+
+import (
+	"context"
+	"log/slog"
+	"testing"
+
+	"github.com/stretchr/testify/mock"
+)
+
+func TestLevelHandler(t *testing.T) {
+	mockHandler := &MockHandler{}
+	logger := slog.New(NewLevelHandler(mockHandler, slog.LevelInfo))
+
+	mockHandler.On("Enabled", mock.Anything, slog.LevelInfo).Return(true)
+	mockHandler.On("Enabled", mock.Anything, slog.LevelWarn).Return(true)
+	mockHandler.On("Enabled", mock.Anything, slog.LevelError).Return(true)
+
+	logger.Debug("debug")
+	logger.Info("info")
+	logger.Warn("warn")
+	logger.Error("error")
+
+	mockHandler.AssertExpectations(t)
+}
+
+type MockHandler struct {
+	mock.Mock
+}
+
+func (h *MockHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	args := h.Called(ctx, level)
+	return args.Bool(0)
+}
+
+func (h *MockHandler) WithGroup(name string) slog.Handler {
+	return h
+}
+
+func (h *MockHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return h
+}
+
+func (h *MockHandler) Handle(ctx context.Context, record slog.Record) error {
+	return nil
+}