fix: add correct context propagation for logs (#1118)

Author: giortzisg

log.go

@@ -10,7 +10,7 @@ import (
 	"time"
 
 	"github.com/getsentry/sentry-go/attribute"
-	debuglog "github.com/getsentry/sentry-go/internal/debuglog"
+	"github.com/getsentry/sentry-go/internal/debuglog"
 )
 
 type LogLevel string
@@ -90,20 +90,30 @@ func (l *sentryLogger) log(ctx context.Context, level LogLevel, severity int, me
 	if message == "" {
 		return
 	}
-	hub := GetHubFromContext(ctx)
-	if hub == nil {
-		hub = CurrentHub()
-	}
-
 	var traceID TraceID
 	var spanID SpanID
 	var span *Span
 	var user User
 
+	span = SpanFromContext(ctx)
+	if span == nil {
+		span = SpanFromContext(l.ctx)
+	}
+	hub := GetHubFromContext(ctx)
+	if hub == nil {
+		hub = GetHubFromContext(l.ctx)
+	}
+	if hub == nil {
+		hub = CurrentHub()
+	}
+
 	scope := hub.Scope()
 	if scope != nil {
 		scope.mu.Lock()
-		span = scope.span
+		// Use span from hub only as last resort
+		if span == nil {
+			span = scope.span
+		}
 		if span != nil {
 			traceID = span.TraceID
 			spanID = span.SpanID

log_context_test.go

@@ -0,0 +1,76 @@
+package sentry
+
+import (
+	"context"
+	"testing"
+
+	"github.com/getsentry/sentry-go/internal/testutils"
+)
+
+func TestSentryLogger_ShouldLinkToCorrectSpan(t *testing.T) {
+	transport := &MockTransport{}
+	err := Init(ClientOptions{
+		Dsn:              testDsn,
+		EnableTracing:    true,
+		TracesSampleRate: 1.0,
+		EnableLogs:       true,
+		Transport:        transport,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer Flush(testutils.FlushTimeout())
+
+	hub := CurrentHub().Clone()
+	ctx1 := SetHubOnContext(context.Background(), hub)
+	span1 := StartTransaction(ctx1, "request-1")
+	ctx1 = span1.Context()
+	traceID1 := span1.TraceID
+
+	logger := NewLogger(ctx1)
+
+	logger.Info().Emit("Log in request-1")
+	span1.Finish()
+
+	ctx2 := SetHubOnContext(context.Background(), hub)
+	span2 := StartTransaction(ctx2, "request-2")
+	ctx2 = span2.Context()
+	traceID2 := span2.TraceID
+
+	logger.Info().Emit("Log from request-1 logger during request-2")
+	logger.Info().WithCtx(ctx2).Emit("Explicit override to request-2")
+	span2.Finish()
+
+	Flush(testutils.FlushTimeout())
+	events := transport.Events()
+	var logs []struct {
+		message string
+		traceID TraceID
+	}
+
+	for _, event := range events {
+		for _, log := range event.Logs {
+			logs = append(logs, struct {
+				message string
+				traceID TraceID
+			}{
+				message: log.Body,
+				traceID: log.TraceID,
+			})
+		}
+	}
+
+	if len(logs) != 3 {
+		t.Fatalf("Expected 3 logs, got %d", len(logs))
+	}
+
+	if logs[0].traceID != traceID1 {
+		t.Errorf("Log 1: expected TraceID %s (request-1), got %s", traceID1, logs[0].traceID)
+	}
+	if logs[1].traceID != traceID1 {
+		t.Errorf("Log 2: expected TraceID %s (request-1), got %s", traceID1, logs[1].traceID)
+	}
+	if logs[2].traceID != traceID2 {
+		t.Errorf("Log 3: expected TraceID %s (request-2), got %s", traceID2, logs[2].traceID)
+	}
+}

slog/sentryslog.go

@@ -238,6 +238,10 @@ func (h *logHandler) Enabled(_ context.Context, level slog.Level) bool {
 }
 
 func (h *logHandler) Handle(ctx context.Context, record slog.Record) error {
+	// when logging without context, slog passes `context.Background`. Check for span existence to not overwrite the root context.
+	if sentry.GetHubFromContext(ctx) == nil {
+		ctx = h.logger.GetCtx()
+	}
 	// aggregate all attributes
 	attrs := appendRecordAttrsToAttrs(h.attrs, h.groups, &record)
 	if h.option.AddSource {