title: spring-cloud-sleuth in a reactive environment
body: <p>I should say I'm really impressed with the simplicity and usefulness of spring-cloud-sleuth and zipkin. </p>
  
  <p>However, I'm working on a POC for which I'm considering reactive toolkits. Vertx 3 is the first item in my list to try (with spring cloud ecosystem). I'm wondering if Sleuth log tracing would work in a reactive context as I guess it relies on ThreadLocals to pass around the context? Keen to understand where Sleuth would stand in a reactive environment.</p>