Rails Performance Monitoring

Scout Monitoring provides integrated errors, logs, and traces for Rails applications. The Ruby agent includes automatic ActiveRecord N+1 detection, memory bloat identification at the transaction level, Sidekiq and background job monitoring, and auto-instrumentation for Redis, Elasticsearch, and HTTP clients. Scout is built for Rails teams that want all their monitoring signals in one place without enterprise complexity.

Scout is an APM built specifically for Rails teams. It provides transaction tracing with code-level detail via AutoInstruments, automatic N+1 detection in ActiveRecord, memory bloat analysis across controller actions and Sidekiq jobs, error monitoring, and log management. The agent supports Rails 2.2+ and Ruby 2.1+, and instruments ActionController, ActionView, ActionMailer, ActiveRecord, Sidekiq, Redis, and more out of the box. Setup takes under 3 minutes.

Scout automatically detects N+1 query patterns in ActiveRecord without any configuration. The agent monitors database queries within Rails controller actions, ActiveJob tasks, and Sidekiq background jobs, identifies repeated query patterns, and shows the exact code location and performance impact of each N+1. You get the line responsible for the repeated queries, not just a list of slow queries.

Scout auto-instruments Sidekiq out of the box with per-job execution timing, queue depth, error rates, and memory bloat detection. Each Sidekiq job appears as its own transaction in Scout with full trace detail, including any ActiveRecord queries, Redis calls, and HTTP requests made during the job. Resque, GoodJob, Solid Queue, DelayedJob, Shoryuken, and Sneakers are also supported.

Scout detects memory bloat at the transaction level in your Rails application. The agent identifies which specific controller actions, Sidekiq jobs, and code paths are responsible for memory growth, so you can fix the root cause rather than just restarting your Puma or Sidekiq workers. Memory bloat detection requires Ruby 2.1+.

Yes. Scout captures exceptions automatically across Rails controllers, ActiveRecord callbacks, and background job frameworks including Sidekiq, Resque, GoodJob, and DelayedJob. Errors are grouped, linked to the originating transaction trace, and shown alongside log context. You see the error, the trace, and the surrounding log lines in one view.

Yes. Scout enriches your Rails application log output with trace context, so you can filter logs by trace ID and see exactly what happened before, during, and after an issue. Logs are connected to errors and traces in a single view, covering Rails requests, Sidekiq jobs, and background workers.

Scout is built for Rails teams who want to fix problems, not configure an observability platform. New Relic and Datadog are powerful but heavy and designed for operations teams managing large infrastructure. Scout is opinionated for Ruby and Rails, includes automatic ActiveRecord N+1 detection without configuration, and starts at $19 per month. If you want an APM that understands Rails rather than one that treats it as a generic HTTP service, Scout is the better fit.

Yes. Scout offers hosted and local MCP servers with 17 tools that work with Claude Code, Cursor, VS Code Copilot, and any MCP-enabled assistant. You can query your Rails application's errors, traces, ActiveRecord N+1 insights, and Sidekiq job performance in natural language from your editor. The Scout CLI, available via Homebrew, gives you terminal access to the same data in TOON format for LLM consumption. There is also a public API for custom integrations.

Overhead is typically under 1% in production Rails applications. The agent samples expensive operations and uses background threads for data transmission so it does not block requests. Scout instruments Rails at the framework level rather than monkey-patching individual methods, which keeps the footprint small.