Spring Cloud Sleuth loosing ParentSpanId

This repository contains a minor Spring Boot 2 application with the purpose of replicating a bug in Spring Cloud Sleuth where the ParentSpanId is lost on subsequent calls. See gh-949

Run

Execute the following command to start the service on port 8000

$ ./gradlew bootRun | grep -B 3 '^X-B3'

Reproduce

$ curl http://localhost:8000/users

Watch the log outout from the bootRun command

Expected Behaviour

The header X-B3-ParentSpanId should exist on all requests and have the same value.

Actual Behaviour

The header X-B3-ParentSpanId only exists on the first call.

Troubleshooting

• The expected behaviour works before commit f6a0e38c7195b9bd9c418195d0c5e22db4e46de6
• The expected behaviour works when only spring-boot-starter-webflux is added as a dependency (Running in Netty).
• The expected behaviour works when spring-boot-starter-webflux and spring-boot-starter-tomcat are added as dependencies
• The actual behaviour is reproduced when the project contains both a dependency to spring-boot-starter-webflux and spring-boot-starter-web

So my investigation concludes that something happens when spring-boot-starter-web is on the classpath, resulting in a lost context when the second call is performed.

The reason for using both spring-boot-starter-webflux and spring-boot-starter-web is due to the lack of webflux-support in springfox gh-1773