AppSignal Rails 5.1 workaround

config_application.rb

# config/application.rb

# Workaround for making the AppSignal gem work on Rails 5.1.

# Put this after your Rails app module is defined.
# E.g. `module TestApp; class Application < Rails::Application`.
# Safest location being at the end of the `config/application.rb` file.

# Create a new middleware class with a different name so that when the original
# middleware is deleted the newly added one isn't deleted as well, since Rails
# deletes the middleware by name.
class Appsignal::Rack::Rails51Instrumentation < Appsignal::Rack::RailsInstrumentation
end
# Delete original middleware
Rails.application.config.middleware.delete Appsignal::Rack::RailsInstrumentation
# Add the middleware in a new location where it can capture and record the
# error before Rails renders an error page.
Rails.application.config.middleware.insert_after(
  ActionDispatch::DebugExceptions,
  Appsignal::Rack::Rails51Instrumentation
)