EventTimeline

A Rails engine that records method calls during requests so you can see what actually happened.

Why?

You get a bug report: "Order failed for user X". You check the logs, see a 500 error, but the stack trace doesn't tell you what state the app was in or what data was being processed.

EventTimeline records the method calls, parameters, and return values during the request. You visit /event_timeline/sessions/<request_id> and see exactly what happened.

Install

gem 'event_timeline'

bundle install
rails generate event_timeline:install
rails db:migrate

Setup

Tell it what to track:

# config/initializers/event_timeline.rb
EventTimeline.configure do |config|
  config.watch 'app/services'
  config.watch 'app/models'
end

Usage

Make a request, grab the request ID from logs, visit:

/event_timeline/sessions/abc-123-def

You'll see the call timeline with params and return values. If the request crashed, you'll see the exception with its source location and backtrace.

Configuration

EventTimeline.configure do |config|
  # What to track
  config.watch 'app/services'
  config.watch 'lib/payments'

  # Filter sensitive params (these are filtered by default: password, token, secret, etc.)
  config.add_filtered_attributes :credit_card, :ssn

  # Custom filtering
  config.filter_pii do |key, value, context|
    key.to_s.include?('account_number') ? true : nil
  end

  # Retention
  config.max_events_per_correlation = 500
  config.max_total_events = 10_000
  config.max_event_age = 1.month

  # Truncation
  config.max_string_length = 100
  config.max_inspect_length = 200
end

Runtime control

EventTimeline::CallTracker.uninstall!   # stop tracking
EventTimeline::CallTracker.install!     # start tracking
EventTimeline::CallTracker.installed?   # check status

Custom correlation IDs

For background jobs or anything outside a request:

EventTimeline::CurrentCorrelation.id = "import-job-#{job.id}"

Limitations

• Only tracks Ruby method calls (not SQL queries or HTTP calls)
• TracePoint has some overhead - probably don't enable in high-traffic production without sampling
• Large values get truncated

License

MIT