When you are ready to deploy your application, you should lock your bundle to guarantee that dependency versions will no longer change.
$ bundle lock
Learn more: bundle lock
Add your Gemfile and lockfile to source control, but ignore the .bundle folder, which is specific to each machine.
$ echo ".bundle\n" >> .gitignore
$ git add Gemfile Gemfile.lock .gitignore
$ git commit -m "Add bundler"
In your deploy script, after updating to the latest code, install your bundle to ensure all your dependencies are met.
$ bundle install
Start your application servers as usual, and your application will use your bundled environment just like it does locally in development.