Contents

require_relative '../action_pack/utils'

module Datadog
  module Tracing
    module Contrib
      # Rails module includes middlewares that are required for Rails to be properly instrumented.
      module Rails
        # This is only here to catch errors, the Rack module does something very similar, however,
        # since it's not in the same place in the stack, when the Rack middleware is called,
        # error is already swallowed and handled by Rails so we miss the call stack, for instance.
        class ExceptionMiddleware
          def initialize(app)
            @app = app
          end

          def call(env)
            @app.call(env)
          # rubocop:disable Lint/RescueException
          # Here we really want to catch *any* exception, not only StandardError,
          # as we really have no clue of what is in the block,
          # and it is user code which should be executed no matter what.
          # It's not a problem since we re-raise it afterwards so for example a
          # SignalException::Interrupt would still bubble up.
          rescue Exception => e
            span = Tracing.active_span
            if !span.nil? && ActionPack::Utils.exception_is_error?(e)
              # Only set error if it's supposed to be flagged as such
              # e.g. we don't want to flag 404s.
              # You can add custom errors via `config.action_dispatch.rescue_responses`
              span.set_error(e)

              # Some exception gets handled by Rails middleware before it can be set on Rack middleware
              # The rack span is the root span of the request and should make sure it has the full exception
              # set on it.
              env[Contrib::Rack::Ext::RACK_ENV_REQUEST_SPAN].set_error(e) if env[Contrib::Rack::Ext::RACK_ENV_REQUEST_SPAN]
            end
            raise e
          end
          # rubocop:enable Lint/RescueException
        end
      end
    end
  end
end

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
ddtrace-1.10.1	lib/datadog/tracing/contrib/rails/middlewares.rb
ddtrace-1.10.0	lib/datadog/tracing/contrib/rails/middlewares.rb