Zipkin Reporter 3.3

Zipkin Reporter 3.3 adds a BaseHttpSender type, which eases http library integration. It also adds HttpEndpointSupplier which supports dynamic endpoint discovery such as from Eureka, as well utilities to create constants or rate-limit suppliers. Finally, brave users get a native PROTO3 encoder through the new MutableSpanBytesEncoder type.

These features were made in support of spring-boot, but available to any user with no new dependencies. For example, the PROTO encoder adds no library dependency, even if it increases the size of zipkin-reporter-brave by a couple dozen KB. A lion's share of thanks goes to @reta and @anuraaga who were on design and review duty for several days leading to this.

Here's an example of pulling most of these things together, integrating a sender with spring-cloud-loadbalancer (a client-side loadbalancer library).

This endpoint supplier will get the configuration endpoint value and look up the next target to use with the loadBalancerClient. The rate limiter will ensure a gap of 30 seconds between queries. While below is hard-coded, it covers some routine advanced features formerly only available in spring-cloud-sleuth. Now, anyone can use them!

@Configuration(proxyBeanMethods = false)
public class ZipkinDiscoveryConfiguration {
  @Bean HttpEndpointSupplier.Factory loadbalancerEndpoints(LoadBalancerClient loadBalancerClient) {
    LoadBalancerHttpEndpointSupplier.Factory httpEndpointSupplierFactory =
        new LoadBalancerHttpEndpointSupplier.Factory(loadBalancerClient);
    // don't ask more than 30 seconds (just to show)
    return HttpEndpointSuppliers.newRateLimitedFactory(httpEndpointSupplierFactory, 30);
  }

  record LoadBalancerHttpEndpointSupplier(LoadBalancerClient loadBalancerClient, URI virtualURL)
      implements HttpEndpointSupplier {
    record Factory(LoadBalancerClient loadBalancerClient) implements HttpEndpointSupplier.Factory {

      @Override public HttpEndpointSupplier create(String endpoint) {
        return new LoadBalancerHttpEndpointSupplier(loadBalancerClient, URI.create(endpoint));
      }
    }

    @Override public String get() {
      ServiceInstance instance = loadBalancerClient.choose(virtualURL.getHost());
      if (instance != null) {
        return instance.getUri() + virtualURL.getPath();
      }
      throw new IllegalArgumentException(virtualURL.getHost() + " is not registered");
    }

    @Override public void close() {
    }

    @Override public String toString() {
      return "LoadBalancer{" + virtualURL + "}";
    }
  }
}

Full Changelog: https://github.com/openzipkin/zipkin-reporter-java/compare/3.2.1..3.3.0