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Rails

Implement OpenTelemetry instrumentation for Ruby on Rails applications to collect traces, metrics, and monitor HTTP requests using the Ruby OTel SDK.

Note: This guide provides a concise overview based on the official OpenTelemetry documentation. For complete information, please consult the official OpenTelemetry documentation.

Overview​

This guide demonstrates how to:

  • Set up OpenTelemetry instrumentation for Rails applications
  • Configure automatic request and database tracing
  • Implement custom instrumentation
  • Collect HTTP metrics
  • Export telemetry data to Scout Collector

Prerequisites​

Before starting, ensure you have:

  • Ruby 2.7 or later installed
  • Rails application set up
  • Bundler installed for package management

Required Packages​

Install the following necessary packages by gem install or add it to Gemfile and run bundle install.

gem 'opentelemetry-sdk'
gem 'opentelemetry-exporter-otlp'
gem 'opentelemetry-instrumentation-all'

Traces​

Traces give us the big picture of what happens when a request is made to an application. Whether your application is a monolith with a single database or a sophisticated mesh of services, traces are essential to understanding the full “path” a request takes in your application.

Auto Instrumentation​

config/initializers/otel.rb
require 'opentelemetry/sdk'
require 'opentelemetry/exporter/otlp'

otlp_endpoint = ENV.fetch('OTEL_EXPORTER_OTLP_ENDPOINT', 'http://0.0.0.0:4318')

OpenTelemetry::SDK.configure do |c|
    c.service_name = ENV.fetch('OTEL_SERVICE_NAME', 'rails-app')
    c.add_span_processor(
      OpenTelemetry::SDK::Trace::Export::BatchSpanProcessor.new(
        OpenTelemetry::Exporter::OTLP::Exporter.new(
          endpoint: otlp_endpoint
        )
      )
    )

    c.use_all
end

TRACER = OpenTelemetry.tracer_provider.tracer('rails-app', '0.1.0')

View your traces in the base14 Scout platform.

Note: Ensure your Scout Collector is properly configured to receive and process the trace data.

References​

Official Traces Documentation

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