Instrumentation

Inertia Rails emits ActiveSupport::Notifications events around rendering, prop resolution, and SSR requests. Subscribe to them to trace rendering with OpenTelemetry or AppSignal, log slow pages, or measure how much time your prop blocks take.

Available since:inertia_rails:master

Events

Events fire on every Inertia render. When no subscribers are attached, the overhead is negligible, so there is nothing to enable or disable.

Event	Wraps	Payload
render.inertia_rails	The entire Inertia render, including view rendering	:component, :partial, :ssr
resolve_props.inertia_rails	Prop resolution, where your prop blocks execute	:component, :partial
ssr.inertia_rails	The HTTP call to the SSR server	:url, :component

The payload keys:

• :component — the resolved page component name, such as "users/show".
• :partial — true on partial reloads.
• :ssr — true when the response body came from SSR. It stays false for JSON responses, when SSR is disabled, and when a failed SSR call falls back to client-side rendering.
• :url — the SSR server endpoint the request was sent to.

NOTE

A cached SSR response emits no ssr.inertia_rails event — the cache read is visible through Rails' own cache_read.active_support event instead.

If an instrumented block raises, ActiveSupport records the error in the payload under :exception and :exception_object before re-raising, so failed SSR calls are observable without any extra configuration.

Subscribing

Use the standard ActiveSupport API to consume the events:

ActiveSupport::Notifications.subscribe('ssr.inertia_rails') do |event|
  Rails.logger.info("SSR render of #{event.payload[:component]} took #{event.duration.round(1)}ms")
end

OpenTelemetry

The opentelemetry-instrumentation-active_support gem converts the events into spans nested inside your request traces:

tracer = OpenTelemetry.tracer_provider.tracer('inertia_rails')

%w[render.inertia_rails resolve_props.inertia_rails ssr.inertia_rails].each do |event|
  OpenTelemetry::Instrumentation::ActiveSupport.subscribe(tracer, event)
end

Each span carries the payload as attributes, so you can group latency by page component, alert on SSR error rates, or see which SQL queries run inside prop resolution. This is also the path to any backend that ingests OpenTelemetry traces, such as Datadog or Sentry.

APMs

AppSignal needs no wiring: its Ruby agent records ActiveSupport::Notifications events automatically, and they appear in the timeline of each performance sample grouped under inertia_rails. New Relic subscribes natively once you list the event names in active_support_custom_events_names. Other APMs consume the events through the OpenTelemetry setup above or their own tracing APIs.