# Error Monitoring with Sentry

Sentry is a powerful error tracking tool that helps you monitor and fix crashes in real-time. Adding it to your Lightning Rails project gives you instant visibility into production issues with stack traces, request context, and more. ### Installation The Sentry SDK for Rails comes as two gems. Add them to your `Gemfile`: ```ruby gem "sentry-ruby" gem "sentry-rails" ``` Then install the gems: ```bash bundle install ``` *** ### Configure SDK Generate the initializer with: ```bash rails generate sentry ``` This creates `config/initializers/sentry.rb`. Now edit the generated file to include your configuration: ```ruby if Rails.env.production? Sentry.init do |config| config.dsn = 'https://8f1bc0b22a55bb483283e664f9fb421f@o4509708042043392.ingest.us.sentry.io/4509789067608064' config.breadcrumbs_logger = [:active_support_logger, :http_logger] # Add data like request headers and IP for users, # see https://docs.sentry.io/platforms/ruby/data-management/data-collected/ for more info config.send_default_pii = true end end ``` > 💡 Make sure to only enable this in production by wrapping it in `if Rails.env.production?` , we don't want to spam our email with error messages when developing ;) *** ### Verify It’s Working You can test the setup by triggering a sample error in the production console. ```ruby begin 1 / 0 rescue ZeroDivisionError => exception Sentry.capture_exception(exception) end Sentry.capture_message("test message") ``` This should send both the exception and the message to your Sentry dashboard. *** ### Optional: Trace Propagation (Frontend + Backend) If you're using frontend Sentry, you can enable distributed tracing by leaving this in your layout: ```erb <%= Sentry.get_trace_propagation_meta.html_safe %> ``` It should have been added to your header when you used the generator above. `` tag in `app/views/layouts/application.html.erb`. Happy Bug Tracking! 🐛🦟🕷️🪲