Is it right way that ruby rails installs gem in addition?

please help for protect-rails-application-with-fail2ban.

I’m trying to do it after

It was blocked from the beginning.

In step of
exception_notification installation …

To install exception_notification

In an existing gem file

gem ‘exception_notification’, ‘~> 4.2’, ‘> = 4.2.2’

After inserting

$ bundle install --without development, test

It runs without error.

Can I use the exception_notification feature? if not

What else do I need to do next?

After installing exception_notification, I need to apply fail2ban_notifier.rb file …

Do I have to run another command to apply fail2ban_notifier.rb?

if not

Can I just save fail2ban_notifier.rb? If so, what is the path to save?