1 files changed, 33 insertions, 0 deletions
diff --git a/internal/grpc/middleware/featureflag/featureflag_handler.go b/internal/grpc/middleware/featureflag/featureflag_handler.go
new file mode 100644
index 000000000..1342b4d5f
--- /dev/null
+++ b/internal/grpc/middleware/featureflag/featureflag_handler.go
@@ -0,0 +1,33 @@
+package featureflag
+
+import (
+	"context"
+	"sort"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/featureflag"
+)
+
+// FieldsProducer adds feature_flags logging fields to gRPC logs. Only enabled flags are available.
+// The log field looks something like following.
+//
+//	{
+//	   "feature_flags": "feature_a feature_b feature_c"
+//	}
+func FieldsProducer(ctx context.Context, err error) logrus.Fields {
+	var enabledFlags []string
+	for flag, value := range featureflag.FromContext(ctx) {
+		if value {
+			enabledFlags = append(enabledFlags, flag.Name)
+		}
+	}
+	if len(enabledFlags) == 0 {
+		return nil
+	}
+
+	sort.Strings(enabledFlags)
+	return logrus.Fields{
+		"feature_flags": strings.Join(enabledFlags, " "),
+	}
+}