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RubyLLM is a Ruby gem that provides a unified interface for multiple AI providers including OpenAI, Anthropic, Google Gemini, AWS Bedrock, Mistral, and more. Braintrust traces RubyLLM applications to capture LLM calls, tool usage, and performance metrics across any supported provider.
This guide covers manual instrumentation. For quicker setup, use auto-instrumentation.

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Setup

Install the Braintrust Ruby SDK and RubyLLM: 
gem install braintrust ruby_llm
Configure your environment variables:
.env
BRAINTRUST_API_KEY=your-api-key

# Configure your preferred provider(s)
OPENAI_API_KEY=your-openai-key
# ANTHROPIC_API_KEY=your-anthropic-key
# GOOGLE_API_KEY=your-google-key

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Trace with RubyLLM

Enable automatic tracing by wrapping RubyLLM with Braintrust:
app.rb
require 'braintrust'
require 'ruby_llm'

# Initialize Braintrust
Braintrust.init(default_project: 'My Project')

# Enable automatic tracing for RubyLLM
Braintrust::Trace::Contrib::Github::Crmne::RubyLLM.wrap

# Configure RubyLLM with your provider
RubyLLM.configure do |config|
  config.openai_api_key = ENV['OPENAI_API_KEY']
end

# Create a chat and make requests (automatically traced)
chat = RubyLLM.chat(model: 'gpt-4o-mini')
response = chat.ask('What is machine learning?')

puts response.content
All RubyLLM calls are automatically traced, including:
  • Chat completions across any provider
  • Tool/function calls
  • Token usage metrics
  • Streaming responses

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