Instrument a Ruby App

In this guide, we will walk you through the process of setting up and using OpenTelemetry in Ruby. You will learn how to instrument a simple PHP application to produce traces, metrics, and logs and export them to KloudMate.

Step 1: Prerequisites

Before moving forward ensure that you have the following installed locally:

MRI Ruby >= 3.0, jruby >= 9.3.2.0, or truffleruby >= 22.1
Bundler

Step 2: Example Application

For this tutorial, we will be using a basic Rails application. However, OpenTelemetry Ruby is compatible with other web frameworks such as Sinatra and Rack as well. Feel free to adapt the instructions to your preferred framework.

Step 3: Installation

Start by installing rails.

gem install rails

2. Create an api-only application called dice-ruby.

rails new --api dice-ruby

3. Change into the newly created folder dice-ruby and create a controller for rolling a dice

cd dice-ruby
rails generate controller dice

4. a new file called app/controllers/dice_controller.rb will be created. Open this file and update it with the following code:

class DiceController < ApplicationController
  def roll
    render json: (rand(6) + 1).to_s
  end
end

5. Open the file named config/routes.rb and add the following code to it:

Rails.application.routes.draw do
  get 'rolldice', to: 'dice#roll'
end

6. Run the application with the following command and open localhost:8080/rolldice in your web browser to ensure it is working.

rails server -p 8080

Step 4: Instrumentation

We will be using opentelemetry-sdk and opentelemetry-instrumentation-all packages that provide instrumentations for Rails, Sinatra, several HTTP libraries, and more.

Install the opentelemetry-sdk and opentelemetry-instrumentation-all packages:

bundle add opentelemetry-sdk opentelemetry-instrumentation-all

2. Create a file named config/initializers/opentelemetry.rb and add the following code to it:

# config/initializers/opentelemetry.rb
require 'opentelemetry/sdk'
require 'opentelemetry/instrumentation/all'
OpenTelemetry::SDK.configure do |c|
  c.service_name = 'dice-ruby'
  c.use_all() # enables all instrumentation!
end

Step 5: Run the Instrumented App

1. Run the instrumented application to generate traces

env OTEL_EXPORTER_OTLP_ENDPOINT=https://otel.kloudmate.com:4318 OTEL_EXPORTER_OTLP_HEADERS="Authorization=<PRIVATE_KEY>" OTEL_EXPORTER_OTLP_PROTOCOL=http/json rails server -p 8080

2. Open localhost:8080/rolldice in your web browser and reload the page a few times.

Source URL for the example application: Getting Started with OpenTelemetry Ruby