Integration between Finagle tracing to Zipkin transports including http, kafka and scribe.

Finagle will use a tracer that it detects in the classpath. For example, depending on io.zipkin.finagle:zipkin-finagle-http_2.12 will send to Zipkin over Http.

You can look at the example for this in use.

You can also explicitly choose a tracer, which is more reliable, at the tradeoff of more configuration.

Here an example initializing an http client in scala and java

client = Http.client
             .withTracer(new HttpZipkinTracer())
             .withLabel("frontend") // becomes the zipkin service name
             .newService("remotehost:8080");

client = Http$.MODULE$.client()
              .withTracer(new HttpZipkinTracer())
              .withLabel("frontend") // becomes the zipkin service name
              .newService("remotehost:8080");

zipkin-finagle configuration is via global flags.

Global flags can either be set by system property, or commandline argument (ex if using TwitterServer).

Ex the following are equivalent ways to trace every request:

$ java -Dzipkin.initialSampleRate=1.0 ...
$ java -cp my-twitter-server.jar -zipkin.initialSampleRate=1.0

Here are the flags that apply to all transports:

Adding io.zipkin.finagle:zipkin-finagle-http_2.12 to your classpath will configure Finagle to report trace data to a Zipkin server via HTTP.

Here are the flags that apply to Http:

Ex. Here's how to configure the Zipkin server with a system property:

$ java -Dzipkin.http.host=192.168.99.100:9411 ...

Adding io.zipkin.finagle:zipkin-finagle-kafka_2.12 to your classpath will configure Finagle to report trace data to a Kafka topic. The minimum Kafka server version is 0.8.2.2

Here are the flags that apply to Kafka:

Ex. Here's how to configure the Kafka server with a system property:

$ java -Dzipkin.kafka.bootstrapServers=192.168.99.100 ...

Adding io.zipkin.finagle:zipkin-finagle-scribe_2.12 to your classpath will configure Finagle to report trace data to the zipkin category of Scribe.

Here are the flags that apply to Scribe:

Ex. Here's how to configure the Scribe host with a system property. In this case pointing directly to a zipkin server:

$ java -Dzipkin.scribe.host=zipkinhost:9410 ...

You can also configure zipkin tracers programmatically. Here's an example:

HttpZipkinTracer.Config config = HttpZipkinTracer.Config.builder()
    // The frontend makes a sampling decision (via Trace.letTracerAndId) and propagates it downstream.
    // This property says sample 100% of traces.
    .initialSampleRate(1.0f)
    // All servers need to point to the same zipkin transport
    .host("127.0.0.1:9411").build();

Tracer tracer = HttpZipkinTracer.create(config,
    // print stats about zipkin to the console
    new JavaLoggerStatsReceiver(Logger.getAnonymousLogger()));

The following metrics are reported under a transport-specific category to the configured StatsReceiver. For example, if using kafka, they are reported relative to "zipkin.kafka".