Im using Rails 4.2.7 on Mac OS X (El Capitan). I have this at the end of my Gemfile (for my production environment). I have no other references to puma in my Gmefile …
group :production do
gem 'pg'
gem 'unicorn'
gem 'puma'
end
localhost:networkingproject localuser$ rails s -b 127.0.0.1
=> Booting Puma
=> Rails 4.2.7.1 application starting in development on http://127.0.0.1:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[93431] Puma starting in cluster mode...
[93431] * Version 3.6.0 (ruby 2.3.0-p0), codename: Sleepy Sunday Serenity
[93431] * Min threads: 1, max threads: 6
[93431] * Environment: development
[93431] * Process workers: 1
[93431] * Phased restart available
[93431] * Listening on tcp://127.0.0.1:3000
[93431] Use Ctrl-C to stop
localhost:networkingproject localuser$
localhost:networkingproject localuser$ echo $RAILS_ENV
localhost:networkingproject localuser$ rails s -b 127.0.0.1
Could not find gem 'puma' in any of the gem sources listed in your Gemfile or available on this machine.
Run `bundle install` to install missing gems.
Well, are you sure you don't have puma gem installed (not from your Gemfile)? Try
gem list
to check it and
gem uninstall puma
if you have it and want to remove it to be sure
Anyway, usually bundle install --without production
do the trick