How to detect if my app is running on Heroku?

Question

Is there a way to detect if a rails app is running on Heroku?

I want to make a method like:

def on_heroku?
...
end

Answer 1

def heroku?
  ENV.any? {|x,_| x=~ /^HEROKU/ }
end

Answer 2

You may set your own config vars to use for detection via ENV['var'].

$ heroku config:add I_AM_HEROKU=yes

def on_heroku?
  ENV['I_AM_HEROKU']
end