A Ruby gem for detailed Rails application performance monitoring 📈. Metrics and transaction traces are reported to Scout, a hosted application monitoring service.

The Scout agent is engineered to do some wonderful things:

• A unique focus on identifying those hard-to-investigate outliers like memory bloat, N+1s, and user-specific problems. See an example workflow.
• Low-overhead
• View your performance metrics during development with DevTrace and in production via server_timing.
• Production-Safe profiling of custom code via ScoutProf (BETA).

Add the gem to your Gemfile

gem 'scout_apm'

Add a version of the parser gem that supports your version of Ruby. For example, if you're on Ruby 3.3.0:

gem 'parser', '~> 3.3.0.0'

Update your Gemfile

bundle install

Signup for a Scout account and put the provided config file at RAILS_ROOT/config/scout_apm.yml.

Your config file should look like:

common: &defaults
  name: YOUR_APPLICATION_NAME
  key: YOUR_APPLICATION_KEY
  monitor: true

test:
  monitor: false

production:
  <<: *defaults

To use DevTrace, our free, no-signup, in-browser development profiler:

1. Add the gem to your Gemfile:

# Gemfile
gem 'scout_apm'

2. Start your Rails app with the SCOUT_DEV_TRACE environment variable:

SCOUT_DEV_TRACE=true rails server

• Point your gemfile at your local checkout: gem 'scout_apm', path: '/path/to/scout_apm_ruby
• Compile native code: cd /path/to/scout_apm_ruby && bundle exec rake compile

For the complete list of supported frameworks, Rubies, configuration options and more, see our help site.

Email [email protected] if you need a hand.