Instead of servlet, this uses Spring Boot 2 to create a self-contained application that runs Spring WebFlux 5 controllers.
- brave.example.Frontend and Backend: Rest controllers
- brave.example.AppAutoConfiguration: Sets up the RestTemplate used in the Frontend.
Application code doesn't show any tracing configuration because that's handled by Spring Cloud Sleuth v3, configured by properties.
Sleuth 3.x is based on Brave, providing autoconfiguration of Brave libraries used in other projects, such as span reporting, logging context, sampling and instrumentation. This allowed end users to use properties for configuration instead of Java Config.
In some cases, Sleuth has custom code that used Brave APIs. This example uses Sleuth-specific logic for instrumenting WebFlux and reporting spans to Zipkin.
Starting with version 6, Brave no longer has a dependency on zipkin-reporter, so it can work with 2.x or 3.x. To maintain compatability with existing autoconfiguration, Sleuth requires io.zipkin.reporter2:zipkin-reporter 2.x. Hence, this project overrides the Brave version to 6.x, but leaves the reporter version managed by Sleuth.
This supports discovery of zipkin via Eureka.
To do so, set EUREKA_SERVICE_URL to a possibly authenticated v2 endpoint.
Here are some examples:
- Eureka is on localhost:
EUREKA_SERVICE_URL=http://localhost:8761/eureka/v2 - Eureka is authenticated:
EUREKA_SERVICE_URL=http://username:password@localhost:8761/eureka/v2
Note: EUREKA_SERVICE_URL includes the '/v2' suffix, even though eureka.client.serviceUrl.defaultZone
does not. This is to be consistent with other examples that don't use Spring.