Class: LangsmithrbRails::RequestTracing

Inherits:
Object
  • Object
show all
Defined in:
lib/generators/langsmithrb_rails/tracing/templates/request_tracing.rb

Overview

Middleware for tracing Rails requests in LangSmith

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ RequestTracing 



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# File 'lib/generators/langsmithrb_rails/tracing/templates/request_tracing.rb', line 6

def initialize(app)
  @app = app
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/generators/langsmithrb_rails/tracing/templates/request_tracing.rb', line 10

def call(env)
  # Skip tracing if sampling rate check fails
  return @app.call(env) if rand > LangsmithrbRails::Config[:sampling_rate]

  req = ActionDispatch::Request.new(env)
  
  # Prepare metadata for the trace
  meta = {
    path: req.path,
    method: req.request_method,
    request_id: req.request_id,
    env: LangsmithrbRails::Config[:env]
  }
  
  # Add user reference if available (and not in development/test)
  if defined?(Current) && Current.respond_to?(:user) && Current.user && !%w[development test].include?(Rails.env)
    # Use a hash of the user ID to avoid sending PII
    meta[:user_ref] = Digest::SHA256.hexdigest(Current.user.id.to_s)
  end
  
  # Create the run in LangSmith
  client = LangsmithrbRails::Client.new
  started = Time.now
  
  # Create the run asynchronously if possible
  run = create_run_async(client, {
    name: "rails_request",
    run_type: "request",
    meta: meta.merge(started_at: started.iso8601)
  })
  
  # Store run ID in thread local for child spans
  Thread.current[:langsmith_run_id] = run&.dig(:body, "id")
  
  # Process the request
  status, headers, body = @app.call(env)
  
  # Update the run asynchronously if possible
  if run&.dig(:body, "id")
    update_run_async(client, run.dig(:body, "id"), {
      ended_at: Time.now.iso8601,
      output: { status: status }
    })
  end
  
  # Clean up thread local
  Thread.current[:langsmith_run_id] = nil
  
  [status, headers, body]
rescue => e
  # Log error but don't fail the request
  Rails.logger.error("LangSmith tracing error: #{e.message}")
  
  # Clean up thread local
  Thread.current[:langsmith_run_id] = nil
  
  # Continue with the request
  @app.call(env)
end