Can't change Rack formatter in development environment

[Drowze]

Developing an application, I was given a task to change the logger formatter, so the logs are correctly consumed by our observability stack. It's also a requirement that production logs and development logs go through the same formatter, with minimal change.
To do that, I created a formatter class, registered it and changed my application formatter. Something along the lines of:

class DatadogLogFormatter < Dry::Logger::Formatters::Structured
  def format(entry)
    # ...
  end
end

Dry::Logger.register_formatter(:datadog, DatadogLogFormatter)

module MyApp
  class App < Hanami::App
    config.logger.formatter = :datadog
  end
end

...but that didn't change the log formatting for rack requests on development/testing, which was very confusing at first... Eventually I found out that it was due to how development logging is setup here, where the constructor is hardcodding the formatter on all logs tagged as rack entries. See:

      def development_logger(_env, app_name, **options)
        Dry.Logger(app_name, **options) do |setup|
          setup
            .add_backend(log_if: -> entry { !entry.tag?(:rack) })
            .add_backend(formatter: :rack, log_if: -> entry { entry.tag?(:rack) })
        end
      end

It's a bit annoying, but for now I've worked around this issue by setting a custom logger_constructor as follows:

config.logger.logger_constructor = -> (_env, app_name, **options) { Dry.Logger(app_name, **options) }

[jodosha]

@Drowze Thanks for reporting. I can reproduce the problem.

[solnic]

Should we then discard the default dev/test logger whenever a custom formatter is configured? The default dev/test logger is there for convenience, the common use case is that you want a human-friendly logger so that you can look at your dev/test logs. Personally, if I need a custom logger I just add it as an additional logger, rather than changing the defaults. We can of course make it respect a custom formatter and use it as a trigger to skip the default logger. I'm just trying to make sure that this would be the expected behavior in most cases.