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Expose baggage in log4j context data when there is no current span #19378

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Merged
laurit merged 5 commits into from
Aug 4, 2026
Merged

Expose baggage in log4j context data when there is no current span #19378

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ef5c08d
Expose baggage in log4j context data when there is no current span
trask Aug 3, 2026
018e4ac
Preserve lazy Configuration initialization and use conventional scope…
trask Aug 3, 2026
3df8fa7
Fix javadoc formatting
trask Aug 3, 2026
e361d7c
Avoid extra allocation on no-span log events when baggage is disabled
trask Aug 3, 2026
0c381e6
Avoid baggage context lookup when baggage injection is disabled
trask Aug 4, 2026
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29 changes: 14 additions & 15 deletions ...entelemetry/instrumentation/log4j/contextdata/v2_17/OpenTelemetryContextDataProvider.java
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Original file line number Diff line number Diff line change
Expand Up @@ -57,16 +57,17 @@ private static boolean isConfiguredResourceAttributeAccessible() {
}

/**
* Returns context from the current span when available.
* Returns context from the current span and baggage when available.
*
* @return A map containing string versions of the traceId, spanId, and traceFlags, which can then
* be accessed from layout components
* @return A map containing string versions of the traceId, spanId, traceFlags and baggage entries,
* which can then be accessed from layout components
*/
@Override
public Map<String, String> supplyContextData() {
Context context = Context.current();
Span currentSpan = Span.fromContext(context);
if (!currentSpan.getSpanContext().isValid()) {
SpanContext spanContext = Span.fromContext(context).getSpanContext();
Baggage baggage = Configuration.baggageEnabled ? Baggage.fromContext(context) : Baggage.empty();
if (!spanContext.isValid() && baggage.isEmpty()) {
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return staticContextData;
}

Expand All @@ -77,17 +78,15 @@ public Map<String, String> supplyContextData() {
}

Map<String, String> contextData = new HashMap<>(staticContextData);
SpanContext spanContext = currentSpan.getSpanContext();
contextData.put(contextDataKeys.getTraceIdKey(), spanContext.getTraceId());
contextData.put(contextDataKeys.getSpanIdKey(), spanContext.getSpanId());
contextData.put(contextDataKeys.getTraceFlagsKey(), spanContext.getTraceFlags().asHex());
if (spanContext.isValid()) {
contextData.put(contextDataKeys.getTraceIdKey(), spanContext.getTraceId());
contextData.put(contextDataKeys.getSpanIdKey(), spanContext.getSpanId());
contextData.put(contextDataKeys.getTraceFlagsKey(), spanContext.getTraceFlags().asHex());
}

if (Configuration.baggageEnabled) {
Baggage baggage = Baggage.fromContext(context);
for (Map.Entry<String, BaggageEntry> entry : baggage.asMap().entrySet()) {
// prefix all baggage values to avoid clashes with existing context
contextData.put("baggage." + entry.getKey(), entry.getValue().getValue());
}
for (Map.Entry<String, BaggageEntry> entry : baggage.asMap().entrySet()) {
// prefix all baggage values to avoid clashes with existing context
contextData.put("baggage." + entry.getKey(), entry.getValue().getValue());
}

return contextData;
Expand Down
24 changes: 12 additions & 12 deletions ...y/javaagent/instrumentation/log4j/contextdata/v2_7/SpanDecoratingContextDataInjector.java
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Expand Up @@ -49,24 +49,24 @@ public StringMap injectContextData(List<Property> list, StringMap stringMap) {
}

Context context = Context.current();
Span span = Span.fromContext(context);
SpanContext currentContext = span.getSpanContext();
if (!currentContext.isValid()) {
SpanContext currentContext = Span.fromContext(context).getSpanContext();
Baggage baggage = BAGGAGE_ENABLED ? Baggage.fromContext(context) : Baggage.empty();
if (!currentContext.isValid() && baggage.isEmpty()) {
return staticContextData.isEmpty() ? contextData : newContextData(contextData);
}

StringMap newContextData = newContextData(contextData);
newContextData.putValue(TRACE_ID_KEY, currentContext.getTraceId());
newContextData.putValue(SPAN_ID_KEY, currentContext.getSpanId());
newContextData.putValue(TRACE_FLAGS_KEY, currentContext.getTraceFlags().asHex());
if (currentContext.isValid()) {
newContextData.putValue(TRACE_ID_KEY, currentContext.getTraceId());
newContextData.putValue(SPAN_ID_KEY, currentContext.getSpanId());
newContextData.putValue(TRACE_FLAGS_KEY, currentContext.getTraceFlags().asHex());
}

if (BAGGAGE_ENABLED) {
Baggage baggage = Baggage.fromContext(context);
for (Map.Entry<String, BaggageEntry> entry : baggage.asMap().entrySet()) {
// prefix all baggage values to avoid clashes with existing context
newContextData.putValue("baggage." + entry.getKey(), entry.getValue().getValue());
}
for (Map.Entry<String, BaggageEntry> entry : baggage.asMap().entrySet()) {
// prefix all baggage values to avoid clashes with existing context
newContextData.putValue("baggage." + entry.getKey(), entry.getValue().getValue());
}

return newContextData;
}

Expand Down
11 changes: 9 additions & 2 deletions .../testing/src/main/java/io/opentelemetry/instrumentation/log4j/contextdata/Log4j2Test.java
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Original file line number Diff line number Diff line change
Expand Up @@ -43,8 +43,11 @@ private String getLoggingKey(String key) {
void testNoIdsWhenNoSpan() {
Logger logger = LogManager.getLogger("TestLogger");

logger.info("log message 1");
logger.info("log message 2");
Baggage baggage = Baggage.empty().toBuilder().put("baggage_key", "baggage_value").build();
try (Scope unusedScope = baggage.makeCurrent()) {
logger.info("log message 1");
logger.info("log message 2");
}

List<ListAppender.LoggedEvent> events = ListAppender.get().getEvents();

Expand All @@ -55,12 +58,16 @@ void testNoIdsWhenNoSpan() {
assertThat(event.getContextData().get(getLoggingKey("trace_id"))).isNull();
assertThat(event.getContextData().get(getLoggingKey("span_id"))).isNull();
assertThat(event.getContextData().get(getLoggingKey("trace_flags"))).isNull();
assertThat(event.getContextData().get("baggage.baggage_key"))
.isEqualTo(expectBaggage() ? "baggage_value" : null);
},
event -> {
assertThat(event.getMessage()).isEqualTo("log message 2");
assertThat(event.getContextData().get(getLoggingKey("trace_id"))).isNull();
assertThat(event.getContextData().get(getLoggingKey("span_id"))).isNull();
assertThat(event.getContextData().get(getLoggingKey("trace_flags"))).isNull();
assertThat(event.getContextData().get("baggage.baggage_key"))
.isEqualTo(expectBaggage() ? "baggage_value" : null);
});
}

Expand Down
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