OpenTelemetry auto instrucmentatio java + log4j sample

Steps to run the example

1. wget https://github.com/open-telemetry/opentelemetry-java-instrumentation/releases/latest/download/opentelemetry-javaagent-all.jar

2. ./gradlew build

3. starting java app - with logging exporter

java -javaagent:./opentelemetry-javaagent-all.jar \
-Dotel.exporter=logging  \
-jar -Dlogging.config="classpath:/log4j2.xml"  \
build/libs/rest-service-0.0.1-SNAPSHOT.jar

4. starting java app - with jaeger exporter :

java -javaagent:./opentelemetry-javaagent-all.jar \
-Dotel.exporter.jaeger.service.name=sample-app  \
-Dotel.exporter=jaeger  \
-jar -Dlogging.config="classpath:/log4j2.xml"  \
build/libs/rest-service-0.0.1-SNAPSHOT.jar

5. open the url: http://localhost:8080/greeting and look at the console logs. The log enties will show traceId and spandId like this: [traceId=....] [spanId=....].