Improve support for nested Rack middlewares #1100
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When more of our Rack, Rails and Sinatra middlewares are nested in one app, improve reporting for those requests. This follows PRs #1089 for Rails and #1097 for Sinatra. This change improves this reporting for Rack apps using the GenericInstrumentation middleware. Other than supporting this scenario better, no one should notice this change. ## Refactor details I've refactored the SinatraInstrumentation middleware to inherit from a new AbstractMiddleware which includes much of the behavior from the GenericInstrumentation and previous SinatraInstrumentation implementations. All the logic for nested instrumentation middlewares are now handled in this AbstractMiddleware. Subclasses of AbstractMiddleware can set their library's specific metadata using the `add_transaction_metadata_before` and `add_transaction_metadata_after` methods, along with specifying the `request_class`, `params_method` and `instrument_span_name` settings. This already works with the EventHandler, as both set the transaction on the request env to detect nested instrumentation. An app could add both the EventHandler and a subclass of the AbstractMiddleware, and it would report the request transaction properly. ## GenericInstrumentation I've kept the GenericInstrumentation middleware. The only thing it really does different that we don't want to put in the AbstractMiddleware is the fallback to the "unknown" action name. I didn't want to break existing behavior, so that is all it still does. If we move the GenericInstrumentation action name fallback to the AbstractMiddleware, we may be reporting more requests than we want for other middlewares that inherit from it. For example, for Rails app, I also want to use this AbstractMiddleware, and it relies on asset requests having no action name so the extension can drop them. That way we don't report transactions for asset requests. ## Next steps If this change is approved, I will update the other Rack instrumentations, like Rails, Grape and Padrino.
tombruijn
changed the title
unflxw
approved these changes
Jun 21, 2024
| Appsignal.internal_logger.debug "Initializing Appsignal::Rack::GenericInstrumentation" | ||
| @app = app | ||
| @options = options | ||
| options[:instrument_span_name] ||= "process_action.generic" |
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Perhaps we could use .rack as the category group, which already has a defined color.
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I want to go through all these event names some time later, because they report process_action which makes no sense for a rack middleware. The generic group isn't a good name either, we can change it to rack, but I'd rather do that later.
This was referenced Jun 21, 2024
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When more of our Rack, Rails and Sinatra middlewares are nested in one app, improve reporting for those requests. This follows PRs #1089 for Rails and #1097 for Sinatra. This change improves this reporting for Rack apps using the GenericInstrumentation middleware. Other than supporting this scenario better, no one should notice this change.
Refactor details
I've refactored the SinatraInstrumentation middleware to inherit from a new AbstractMiddleware which includes much of the behavior from the GenericInstrumentation and previous SinatraInstrumentation implementations.
All the logic for nested instrumentation middlewares are now handled in this AbstractMiddleware.
Subclasses of AbstractMiddleware can set their library's specific metadata using the
add_transaction_metadata_beforeandadd_transaction_metadata_aftermethods, along with specifying therequest_class,params_methodandinstrument_span_namesettings.This already works with the EventHandler, as both set the transaction on the request env to detect nested instrumentation. An app could add both the EventHandler and a subclass of the AbstractMiddleware, and it would report the request transaction properly.
GenericInstrumentation
I've kept the GenericInstrumentation middleware. The only thing it really does different that we don't want to put in the AbstractMiddleware is the fallback to the "unknown" action name. I didn't want to break existing behavior, so that is all it still does.
If we move the GenericInstrumentation action name fallback to the AbstractMiddleware, we may be reporting more requests than we want for other middlewares that inherit from it. For example, for Rails app, I also want to use this AbstractMiddleware, and it relies on asset requests having no action name so the extension can drop them. That way we don't report transactions for asset requests.
Next steps
If this change is approved, I will update the other Rack instrumentations, like Rails, Grape and Padrino.
Part of #329