Trying a feature on a percentage of users.

controlled_rollout.py

# Modified version of the snippet that appears in:
# http://blog.disqus.com/post/789540337/partial-deployment-with-feature-switches

def get_for_user(self, user):
  """Returns true if experimental feature should be enabled for users.
  
  percent_range determines the set of users that get access.
  E.g. (35, 45) does NOT mean 35-45% of users get access!
       It means that 10% of users get access, but only users with an ID ending in 35 to 44.
  """
  if 'users' in self.value:
    percent_range = (0, 10)  # 10% of users.
    return percent_range[0] <= user.id % 100 < percent_range[1]
  return False