jaeger-ruby

Jaeger Ruby Tracing Example

This simple Sinatra app shows how to use the Jaeger Ruby client. It generates a random number and creates spans showing the Fibonacci sequence that gets the closest to that number.

Setup and configuration

Install the gem

Clone the jaeger-client-ruby repo and cd into it.

git clone https://github.com/signalfx/jaeger-client-ruby

cd jaeger-client-ruby

Set up dependencies and run the install command.

bin/setup

bundle exec rake install

Configure project

In the application's Gemfile, add this line.

gem 'jaeger-client'

Add these imports:

require 'opentracing'
require 'jaeger/client'
require 'jaeger/client/http_sender'

By default, the tracer uses the UDP sender with the Jaeger client. To set up the HTTP sender to the SignalFx endpoint, it must first be configured and then passed to the tracer.

headers = { "X-SF-Token" => accessToken }

encoder = Jaeger::Client::Encoders::ThriftEncoder.new(service_name: "service_name")
http_sender = Jaeger::Client::HttpSender.new(
    url: "http://ingest.signalfx.com/v1/traces",
    headers: headers
    encoder: encoder)

OpenTracing.global_tracer = Jaeger::Client.build(service_name: "service_name", sender: http_sender)

Creating spans

When creating spans in block form, the scope is passed as an optional argument.

OpenTracing.start_active_span("span_name") do |scope|
    ...
end

The current span can be accessed from elsewhere with

span = OpenTracing.active_span

A child span can be started by getting the current active scope and then starting a new span.

scope = OpenTracing.scope_manager.active
span = OpenTracing.start_active_span("child_span", child_of: scope.span)

A parent span and child span can be manually managed.

parent = OpenTracing.start_active_span("parent_span")
child = OpenTracing.start_active_span("child_span", child_of: parent)

For more examples on usage, visit opentracing-ruby

Running the example.

Install the gem as shown above in the Setup and Configuration section.

Set the SIGNALFX_ACCESS_TOKEN environment variable to a valid token.

export SIGNALFX_ACCESS_TOKEN=<token>

Run the example with

ruby example.rb

To trigger a trace, nagivate to http://localhost:4567/ in a browser, or do

curl localhost:4567

This will return a random number and spans showing the Fibonacci sequence up to the generated number will be exported.