Autodetect open telemetry so to remap some MDC fields so that GCP tra…

…cing picks them up

gcp/logback-logstash-encoder-gcp/src/main/java/no/entur/logging/cloud/gcp/logback/logstash/StackdriverLogstashEncoder.java

@@ -7,6 +7,7 @@
 import net.logstash.logback.composite.loggingevent.LogLevelJsonProvider;
 import net.logstash.logback.composite.loggingevent.LogLevelValueJsonProvider;
 import net.logstash.logback.composite.loggingevent.LoggingEventJsonProviders;
+import net.logstash.logback.composite.loggingevent.MdcJsonProvider;
 import net.logstash.logback.composite.loggingevent.MessageJsonProvider;
 import net.logstash.logback.composite.loggingevent.StackTraceJsonProvider;
 import net.logstash.logback.composite.loggingevent.TagsJsonProvider;
@@ -34,6 +35,8 @@ protected AbstractCompositeJsonFormatter<ILoggingEvent> createFormatter() {
 		LoggingEventJsonProviders loggingEventJsonProviders = formatter.getProviders();
 		List<JsonProvider<ILoggingEvent>> providers = new ArrayList<>(loggingEventJsonProviders.getProviders());
 
+		boolean openTelemetry = detectOpenTelemetry(); // TODO check if open telemetry is on class path
+
 		for (JsonProvider<ILoggingEvent> jsonProvider : providers) {
 			if(jsonProvider instanceof MessageJsonProvider) {
 				loggingEventJsonProviders.removeProvider(jsonProvider);
@@ -49,13 +52,31 @@ protected AbstractCompositeJsonFormatter<ILoggingEvent> createFormatter() {
 				// stackdriver supports the equivalent functionality as the log level value directly in queries
 				// see https://cloud.google.com/logging/docs/view/advanced-filters
 				loggingEventJsonProviders.removeProvider(jsonProvider);
+			} else if(jsonProvider instanceof MdcJsonProvider p) {
+				if(openTelemetry) {
+					p.addExcludeMdcKeyName("traceId");
+					p.addExcludeMdcKeyName("spanId");
+				}
 			}
 		}
 
+		if(openTelemetry) {
+			loggingEventJsonProviders.addProvider(new StackdriverOpenTelemetryTraceJsonProvider());
+		}
+
 		loggingEventJsonProviders.addProvider(new StackdriverLogSeverityJsonProvider());
 		loggingEventJsonProviders.addProvider(new StackdriverMessageJsonProvider());
 
 		return formatter;
 	}
-
+
+	private boolean detectOpenTelemetry() {
+		try {
+			Class.forName("io.opentelemetry.api.OpenTelemetry");
+			return true;
+		} catch (Exception e) {
+			return false;
+		}
+	}
+
 }

gcp/logback-logstash-encoder-gcp/src/main/java/no/entur/logging/cloud/gcp/logback/logstash/StackdriverOpenTelemetryTraceJsonProvider.java

@@ -0,0 +1,38 @@
+package no.entur.logging.cloud.gcp.logback.logstash;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import com.fasterxml.jackson.core.JsonGenerator;
+import net.logstash.logback.composite.AbstractJsonProvider;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ *
+ * Add fields so to rename the traceId MDC field to trace for use with GCP Trace explorer.<br>
+ * <br>
+ * See https://cloud.google.com/logging/docs/structured-logging for more info.
+ * <br><br>
+ * Note: Exclude traceId and spanId in MDC provider.
+ *
+ */
+
+public class StackdriverOpenTelemetryTraceJsonProvider extends AbstractJsonProvider<ILoggingEvent> {
+
+    @Override
+    public void writeTo(JsonGenerator generator, ILoggingEvent iLoggingEvent) throws IOException {
+        Map<String, String> mdcPropertyMap = iLoggingEvent.getMDCPropertyMap();
+
+        // copy value to another field name
+        String trace = mdcPropertyMap.get("traceId");
+        if(trace != null) {
+            generator.writeStringField("trace", trace);
+        }
+
+        // copy through
+        String spanId = mdcPropertyMap.get("spanId");
+        if(spanId != null) {
+            generator.writeStringField("spanId", spanId);
+        }
+    }
+}