LogstashStructuredLogFormatter Class — spring-boot Architecture

Source Code

core/spring-boot/src/main/java/org/springframework/boot/logging/logback/LogstashStructuredLogFormatter.java lines 51–106

class LogstashStructuredLogFormatter extends JsonWriterStructuredLogFormatter<ILoggingEvent> {

	private static final PairExtractor<KeyValuePair> keyValuePairExtractor = PairExtractor.of((pair) -> pair.key,
			(pair) -> pair.value);

	LogstashStructuredLogFormatter(@Nullable StackTracePrinter stackTracePrinter, ContextPairs contextPairs,
			ThrowableProxyConverter throwableProxyConverter,
			@Nullable StructuredLoggingJsonMembersCustomizer<?> customizer) {
		super((members) -> jsonMembers(stackTracePrinter, contextPairs, throwableProxyConverter, members), customizer);
	}

	private static void jsonMembers(@Nullable StackTracePrinter stackTracePrinter, ContextPairs contextPairs,
			ThrowableProxyConverter throwableProxyConverter, JsonWriter.Members<ILoggingEvent> members) {
		Extractor extractor = new Extractor(stackTracePrinter, throwableProxyConverter);
		members.add("@timestamp", ILoggingEvent::getInstant).as(LogstashStructuredLogFormatter::asTimestamp);
		members.add("@version", "1");
		members.add("message", ILoggingEvent::getFormattedMessage);
		members.add("logger_name", ILoggingEvent::getLoggerName);
		members.add("thread_name", ILoggingEvent::getThreadName);
		members.add("level", ILoggingEvent::getLevel);
		members.add("level_value", ILoggingEvent::getLevel).as(Level::toInt);
		members.add().usingPairs(contextPairs.flat("_", (pairs) -> {
			pairs.addMapEntries(ILoggingEvent::getMDCPropertyMap);
			pairs.add(ILoggingEvent::getKeyValuePairs, keyValuePairExtractor);
		}));
		members.add("tags", ILoggingEvent::getMarkerList)
			.whenNotNull()
			.as(LogstashStructuredLogFormatter::getMarkers)
			.whenNotEmpty();
		Function<@Nullable ILoggingEvent, @Nullable Object> getThrowableProxy = (event) -> (event != null)
				? event.getThrowableProxy() : null;
		members.add("stack_trace", (event) -> event).whenNotNull(getThrowableProxy).as(extractor::stackTrace);
	}

	private static String asTimestamp(Instant instant) {
		OffsetDateTime offsetDateTime = OffsetDateTime.ofInstant(instant, ZoneId.systemDefault());
		return DateTimeFormatter.ISO_OFFSET_DATE_TIME.format(offsetDateTime);
	}

	private static Set<String> getMarkers(List<Marker> markers) {
		Set<String> result = new LinkedHashSet<>();
		addMarkers(result, markers.iterator());
		return result;
	}

	private static void addMarkers(Set<String> result, Iterator<Marker> iterator) {
		while (iterator.hasNext()) {
			Marker marker = iterator.next();
			result.add(marker.getName());
			if (marker.hasReferences()) {
				addMarkers(result, marker.iterator());
			}
		}
	}

}