PostHog error tracking for Ruby on Rails

Reference files

• references/ruby-on-rails.md

  - Ruby on rails error tracking installation - docs

• references/fingerprints.md

  - Fingerprints - docs

• references/alerts.md

  - Send error tracking alerts - docs

• references/monitoring.md

  - Monitor and search issues - docs

• references/assigning-issues.md

  - Assign issues to teammates - docs

• references/upload-source-maps.md

  - Upload source maps - docs

Key principles

• Environment variables: Always use environment variables for PostHog keys and host URLs. Never hardcode them.
• Minimal changes: Add error tracking alongside existing error handling. Don't replace or restructure existing error handling code.
• Autocapture first: Enable exception autocapture in the SDK initialization before adding manual captures.
• Source maps: Upload source maps so stack traces resolve to original source code, not minified bundles.
• Manual capture for boundaries: Use

  captureException()

  at error boundaries and catch blocks for errors that don't propagate to the global handler.

Framework guidelines

• Use posthog-rails gem alongside posthog-ruby for automatic exception capture and ActiveJob instrumentation
• Run

  rails generate posthog:install

  to create the initializer, or manually create config/initializers/posthog.rb
• Configure auto_capture_exceptions: true to automatically track unhandled exceptions in controllers
• Configure report_rescued_exceptions: true to also capture exceptions that Rails rescues (e.g. with rescue_from)
• Configure auto_instrument_active_job: true to track background job failures with job class, queue, and arguments
• Use PostHog.capture() and PostHog.identify() class-level methods (NOT instance methods) — the posthog-rails gem manages the client lifecycle via PostHog.init
• Do NOT manually create PostHog::Client instances in Rails — use PostHog.init in the initializer and PostHog.capture/identify everywhere else
• capture_exception takes POSITIONAL args: PostHog.capture_exception(exception, distinct_id, additional_properties) — do NOT use keyword args
• Define posthog_distinct_id on the User model for automatic user association in error reports — posthog-rails auto-detects by trying: posthog_distinct_id, distinct_id, id, pk, uuid (in order)
• For ActiveJob user association, use the class-level DSL

  posthog_distinct_id ->(user) { user.email }

  or pass user_id: in a hash argument
• Store API key in Rails credentials or environment variables, never hardcode
• For frontend tracking alongside posthog-rails, add the posthog-js snippet to the layout template — posthog-js handles pageviews, session replay, and client-side errors while posthog-ruby handles backend events, server errors, feature flags, and background jobs
• posthog-ruby is the Ruby SDK gem name (add

  gem 'posthog-ruby'

  to Gemfile) but require it with

  require 'posthog'

  (NOT

  require 'posthog-ruby'

  )
• Use PostHog::Client.new(api_key: key, host: host) for instance-based initialization in scripts and CLIs
• In CLIs and scripts: MUST call client.shutdown before exit or all events are lost
• Use begin/rescue/ensure with shutdown in the ensure block for proper cleanup
• capture and identify take a single hash argument: client.capture(distinct_id: 'user_123', event: 'my_event', properties: { key: 'value' })
• capture_exception takes POSITIONAL args (not keyword): client.capture_exception(exception, distinct_id, additional_properties) — do NOT use

  distinct_id:

  keyword syntax