Merge pull request newrelic#881 from adomaskizogian/develop

feat: slog: automatically reference transaction from context

.github/workflows/ci.yaml

@@ -30,6 +30,7 @@ jobs:
           - dirs: v3/integrations/logcontext-v2/nrlogrus
           - dirs: v3/integrations/logcontext-v2/nrzerolog
           - dirs: v3/integrations/logcontext-v2/nrzap
+          - dirs: v3/integrations/logcontext-v2/nrslog
           - dirs: v3/integrations/logcontext-v2/nrwriter
           - dirs: v3/integrations/logcontext-v2/zerologWriter
           - dirs: v3/integrations/logcontext-v2/logWriter
@@ -138,4 +139,4 @@ jobs:
           else
             echo "Directory /app/$dir does not exist."
           fi
-        done
+        done

v3/integrations/logcontext-v2/nrslog/handler.go

@@ -39,6 +39,7 @@ func JSONHandler(app *newrelic.Application, w io.Writer, opts *slog.HandlerOptio
 }
 
 // WithTransaction creates a new Slog Logger object to be used for logging within a given transaction.
+// Calling this function with a logger having underlying TransactionFromContextHandler handler is a no-op.
 func WithTransaction(txn *newrelic.Transaction, logger *slog.Logger) *slog.Logger {
 	if txn == nil || logger == nil {
 		return logger
@@ -56,6 +57,7 @@ func WithTransaction(txn *newrelic.Transaction, logger *slog.Logger) *slog.Logge
 
 // WithTransaction creates a new Slog Logger object to be used for logging within a given transaction it its found
 // in a context.
+// Calling this function with a logger having underlying TransactionFromContextHandler handler is a no-op.
 func WithContext(ctx context.Context, logger *slog.Logger) *slog.Logger {
 	if ctx == nil {
 		return logger
@@ -181,3 +183,41 @@ func (h NRHandler) WithGroup(name string) slog.Handler {
 		txn:     h.txn,
 	}
 }
+
+// NRHandler is an Slog handler that includes logic to implement New Relic Logs in Context.
+// New Relic transaction value is taken from context. It cannot be set directly.
+// This serves as a quality of life improvement for cases where slog.Default global instance is
+// referenced, allowing to use slog methods directly and maintaining New Relic instrumentation.
+type TransactionFromContextHandler struct {
+	NRHandler
+}
+
+// WithTransactionFromContext creates a wrapped NRHandler, enabling it to automatically reference New Relic
+// transaction from context.
+func WithTransactionFromContext(handler NRHandler) TransactionFromContextHandler {
+	return TransactionFromContextHandler{handler}
+}
+
+// Handle handles the Record.
+// It will only be called when Enabled returns true.
+// The Context argument is as for Enabled and NewRelic transaction.
+// Canceling the context should not affect record processing.
+// (Among other things, log messages may be necessary to debug a
+// cancellation-related problem.)
+//
+// Handle methods that produce output should observe the following rules:
+//   - If r.Time is the zero time, ignore the time.
+//   - If r.PC is zero, ignore it.
+//   - Attr's values should be resolved.
+//   - If an Attr's key and value are both the zero value, ignore the Attr.
+//     This can be tested with attr.Equal(Attr{}).
+//   - If a group's key is empty, inline the group's Attrs.
+//   - If a group has no Attrs (even if it has a non-empty key),
+//     ignore it.
+func (h TransactionFromContextHandler) Handle(ctx context.Context, record slog.Record) error {
+	if txn := newrelic.FromContext(ctx); txn != nil {
+		return h.NRHandler.WithTransaction(txn).Handle(ctx, record)
+	}
+
+	return h.NRHandler.Handle(ctx, record)
+}

v3/integrations/logcontext-v2/nrslog/handler_test.go

@@ -258,3 +258,40 @@ func TestWithGroup(t *testing.T) {
 	}
 
 }
+
+func TestTransactionFromContextHandler(t *testing.T) {
+	app := integrationsupport.NewTestApp(integrationsupport.SampleEverythingReplyFn,
+		newrelic.ConfigAppLogDecoratingEnabled(true),
+		newrelic.ConfigAppLogForwardingEnabled(true),
+	)
+
+	out := bytes.NewBuffer([]byte{})
+	message := "Hello World!"
+
+	handler := TextHandler(app.Application, out, &slog.HandlerOptions{})
+	log := slog.New(WithTransactionFromContext(handler))
+
+	txn := app.Application.StartTransaction("my txn")
+	ctx := newrelic.NewContext(context.Background(), txn)
+	txninfo := txn.GetLinkingMetadata()
+
+	log.InfoContext(ctx, message)
+
+	txn.End()
+
+	logcontext.ValidateDecoratedOutput(t, out, &logcontext.DecorationExpect{
+		EntityGUID: integrationsupport.TestEntityGUID,
+		Hostname:   host,
+		EntityName: integrationsupport.SampleAppName,
+	})
+
+	app.ExpectLogEvents(t, []internal.WantLog{
+		{
+			Severity:  slog.LevelInfo.String(),
+			Message:   message,
+			Timestamp: internal.MatchAnyUnixMilli,
+			SpanID:    txninfo.SpanID,
+			TraceID:   txninfo.TraceID,
+		},
+	})
+}