Zipkin

Development and Testing Set-up

Great efforts have been made to make Zipkin easier to test, develop and experiment against. Zipkin can now be run from a single Docker container or by running its self-contained executable jar without extensive configuration. In its default configuration you will run Zipkin with a HTTP collector, In memory Span storage backend and web UI on port 9411.

Example:

docker run -d -p 9411:9411 openzipkin/zipkin

Middleware Usage

Follow the addsvc example to check out how to wire the Zipkin Middleware. The changes should be relatively minor.

The zipkin-go package has Reporters to send Spans to the Zipkin HTTP and Kafka Collectors.

Configuring the Zipkin HTTP Reporter

To use the HTTP Reporter with a Zipkin instance running on localhost you bootstrap zipkin-go like this:

var (
  serviceName        = "MyService"
  serviceHostPort    = "localhost:8000"
  zipkinHTTPEndpoint = "http://localhost:9411/api/v2/spans"
)

// create an instance of the HTTP Reporter.
reporter := zipkin.NewReporter(zipkinHTTPEndpoint)

// create our tracer's local endpoint (how the service is identified in Zipkin).
localEndpoint, err := zipkin.NewEndpoint(serviceName, serviceHostPort)

// create our tracer instance.
tracer, err = zipkin.NewTracer(reporter, zipkin.WithLocalEndpoint(localEndpoint))
  ...

Tracing Resources

Here is an example of how you could trace resources and work with local spans.

import (
	zipkin "github.com/openzipkin/zipkin-go"
)

func (svc *Service) GetMeSomeExamples(ctx context.Context, ...) ([]Examples, error) {
  // Example of annotating a database query:
  var (
    spanContext model.SpanContext
    serviceName = "MySQL"
    serviceHost = "mysql.example.com:3306"
    queryLabel  = "GetExamplesByParam"
    query       = "select * from example where param = :value"
  )

  // retrieve the parent span from context to use as parent if available.
  if parentSpan := zipkin.SpanFromContext(ctx); parentSpan != nil {
    spanContext = parentSpan.Context()
  }

  // create the remote Zipkin endpoint
  ep, _ := zipkin.NewEndpoint(serviceName, serviceHost)

  // create a new span to record the resource interaction
  span := zipkin.StartSpan(
    queryLabel,
    zipkin.Parent(parentSpan.Context()),
    zipkin.WithRemoteEndpoint(ep),
  )

	// add interesting key/value pair to our span
	span.SetTag("query", query)

	// add interesting timed event to our span
	span.Annotate(time.Now(), "query:start")

	// do the actual query...

	// let's annotate the end...
	span.Annotate(time.Now(), "query:end")

	// we're done with this span.
	span.Finish()

	// do other stuff
	...
}