bketelsen / buffet

OpenTracing middleware for Buffalo

buffet

Buffet is an OpenTracing middleware for buffalo

Usage

In your main:

	tracer, closer := initTracer()
	defer closer.Close()
	opentracing.SetGlobalTracer(tracer)

	fmt.Println(tracer)
	app := actions.App(tracer)

initTracer looks like this:

func initTracer() (opentracing.Tracer, io.Closer) {
	sampler := jaeger.NewConstSampler(true)
	transport, err := udp.NewUDPTransport("", 0)
	if err != nil {
		log.Fatal(err)
	}
	reporter := jaeger.NewRemoteReporter(transport)

	tracer, closer := jaeger.NewTracer(ServiceName, sampler, reporter)
	return tracer, closer

}

Change your App() function to accept your tracer for initialization, and add the middleware:

func App(tracer opentracing.Tracer) *buffalo.App {
	if app == nil {
    ...
		app.Use(buffet.OpenTracing(tracer))
    ...

Then instrument your handlers:

// HomeHandler is a default handler to serve up
// a home page.
func HomeHandler(c buffalo.Context) error {
	slow(c)
	return c.Render(200, r.HTML("index.html"))
}

//BadHandler returns an error
func BadHandler(c buffalo.Context) error {
	return c.Error(401, errors.New("Unauthorized!"))
}
func slow(c buffalo.Context) {
	sp := buffet.ChildSpan("slow", c)
	defer sp.Finish()
	time.Sleep(1 * time.Millisecond)
}

HomeHandler and BadHandler are automatically instrumented because of the middleware. The slow() function isn't, so we pass in the buffalo context and derive a child span from the one in the buffalo context. This creates a child span that belongs to the parent (which was created automatically in the middleware).

buffet's Issues

Show examples using mock tracer

The mock tracer is a really easy way to setup and test without needing a real tracer like jaeger running, etc. I think it would help a lot of people getting started with this project if they saw both examples or tests (or using examples in the tests) on how to use the mock tracer so they can see it happen as they develop, etc.

Also, very nice introduction for the middleware. Great addition to the buffalo ecosystem!

make a NewSpan... function that accepts context.Context