Ignore classes option for Error Tracking

[ryush00]

Is your feature request related to a problem? Please describe.

While there are some errors that can be ignored to a certain extent, such as 404 errors, some 4XX errors should not be ignored.

Compared to other error tracking platforms, while other platforms allow you to ignore certain error classes, datadog ignores all 4XX errors by default. I think this is a bad practice.

If a client writes code incorrectly and gets an error like 422, and it's ignored because it's a 4XX error, it's going to make it harder to trace the error and more likely to cause a failure.

Or, like me, they might wonder why some errors aren't being tracked.

Describe the goal of the feature

It would be much better if we could set which classes to ignore via settings.

Describe alternatives you've considered

It was hardcoded, so there's no alternative options.

Additional context

• Zendesk issue: 1307558
• Improve Rails middleware error handling #345

Below is the configuration documentation for another similar error tracking platform.

• https://docs.bugsnag.com/platforms/ruby/rails/configuration-options/#discard_classes
• https://docs.appsignal.com/guides/filter-data/ignore-errors.html
• https://docs.sentry.io/platforms/ruby/configuration/options/#:~:text=%27production%27%0Aend-,excluded_exceptions,-If%20you%20never

[benoittgt]

Hello @ryush00 🤗

Thanks for the detailed feature request. I started looking into that. Thanks for the links too. I love the very complet implementation made in sentry-ruby with various handling to get constant. Good work Stan 😏.

My todo list:

• By able to choose on Rails integration the list of class exceptions to ignore
• Provide by default a list of exceptions that match the actual behavior to avoid breaking change (?)
• Be able to override the list using constant
• Be able to use regex and not only string class definition
• Document how to exclude some class from default exceptions list

Edit 1:

• By able to choose on Rails integration the list of class exceptions to ignore

I don't think it's a good. Idea I think it's better to make it global and increment default ignored exceptions with plugged integrations.

[benoittgt]

I started to work on this, but before going further. I think we need to hear what would be wanted from dd-trace-rb maintainers.

For example, we could ignore some exceptions on Rails part but still because it's a 5xx it could be grabbed by in the rack tracing part.