Write a more complete Custom Instrumentation

[pbernery]

Problem Statement

The https://docs.sentry.io/platforms/ruby/performance/instrumentation/custom-instrumentation/ documentation explains how to track custom transactions. However, it is not complete, calling start_transaction won't be enough, it has to be attached to the current scope.

One correct way to implement custom can be found in the Sentry client code, for instance https://github.com/getsentry/sentry-ruby/blob/6cdb1fc3b1a7f2f10f2783ba27010522d9bf0af5/sentry-rails/lib/sentry/rails/action_cable.rb, where we can see a creation of a scope, then a transaction, and several other things.

I spent many hours understanding why the sample provided in the first documentation did not show up on the Sentry front. I believe the documentation needs to be more complete.

This documentation should also inform about the limit of spans, which can be found on the SDK creation documentation https://develop.sentry.dev/sdk/performance/#maxspans, but is not mentioned on the client documentation.

Solution Brainstorm

No response

Product Area

Performance