From b264e6bb968cb8a614245348d23099711a868393 Mon Sep 17 00:00:00 2001
From: Robert Fratto <robertfratto@gmail.com>
Date: Thu, 21 Sep 2023 10:17:53 -0400
Subject: [PATCH] slogadapter: check for log level being enabled (#5264)

The custom log.Logger implementation wrapping around a slog.Handler must
check to see if a level is enabled before logging log lines.
---
 internal/slogadapter/gokit.go      |  3 +++
 internal/slogadapter/gokit_test.go | 38 ++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100644 internal/slogadapter/gokit_test.go

diff --git a/internal/slogadapter/gokit.go b/internal/slogadapter/gokit.go
index 72e3dfee4597..598e8a28b7df 100644
--- a/internal/slogadapter/gokit.go
+++ b/internal/slogadapter/gokit.go
@@ -68,5 +68,8 @@ func (sa slogAdapter) Log(kvps ...interface{}) error {
 		})
 	}
 
+	if !sa.h.Enabled(context.Background(), rec.Level) {
+		return nil
+	}
 	return sa.h.Handle(context.Background(), rec)
 }
diff --git a/internal/slogadapter/gokit_test.go b/internal/slogadapter/gokit_test.go
new file mode 100644
index 000000000000..05fe9694f089
--- /dev/null
+++ b/internal/slogadapter/gokit_test.go
@@ -0,0 +1,38 @@
+package slogadapter
+
+import (
+	"bytes"
+	"log/slog"
+	"testing"
+
+	"github.com/go-kit/log/level"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFiltersLogs(t *testing.T) {
+	var buf bytes.Buffer
+	h := slog.NewTextHandler(&buf, &slog.HandlerOptions{
+		Level: slog.LevelWarn,
+
+		ReplaceAttr: func(groups []string, a slog.Attr) slog.Attr {
+			// Drop timestamps for reproducible tests.
+			if a.Key == slog.TimeKey {
+				return slog.Attr{}
+			}
+
+			return a
+		},
+	})
+
+	l := GoKit(h)
+	level.Debug(l).Log("msg", "debug level log")
+	level.Info(l).Log("msg", "info level log")
+	level.Warn(l).Log("msg", "warn level log")
+	level.Error(l).Log("msg", "error level log")
+
+	expect := `level=WARN msg="warn level log"
+level=ERROR msg="error level log"
+`
+
+	require.Equal(t, expect, buf.String())
+}