rollout
Fast feature flags based on Redis.
Install it
gem install rollout
How it works
Initialize a rollout object. I assign it to a global var.
require 'redis'
$redis = Redis.new
$rollout = Rollout.new($redis)
Update data specific to a feature:
$rollout.set_feature_data(:chat, description: 'foo', release_date: 'bar', whatever: 'baz')
Check whether a feature is active for a particular user:
$rollout.active?(:chat, User.first) # => true/false
Check whether a feature is active globally:
$rollout.active?(:chat)
You can activate features using a number of different mechanisms.
Groups
Rollout ships with one group by default: "all", which does exactly what it
sounds like.
You can activate the all group for the chat feature like this:
$rollout.activate_group(:chat, :all)
You might also want to define your own groups. We have one for our caretakers:
$rollout.define_group(:caretakers) do, user, user.caretaker?
end
You can activate multiple groups per feature.
Deactivate groups like this:
$rollout.deactivate_group(:chat, :all)
Groups need to be defined every time your app starts. The logic is not persisted
anywhere.
Specific Users
You might want to let a specific user into a beta test or something. If that
user isn't part of an existing group, you can let them in specifically:
$rollout.activate_user(:chat, @user)
Deactivate them like this:
$rollout.deactivate_user(:chat, @user)
User Percentages
If you're rolling out a new feature, you might want to test the waters by
slowly enabling it for a percentage of your users.
$rollout.activate_percentage(:chat, 20)
The algorithm for determining which users get let in is this:
CRC32(user.id) < (2**32 - 1) / 100.0 * percentage
So, for 20%, users 0, 1, 10, 11, 20, 21, etc would be allowed in. Those users
would remain in as the percentage increases.
Deactivate all percentages like this:
$rollout.deactivate_percentage(:chat)
Note that activating a feature for 100% of users will also make it active
"globally". That is when calling Rollout#active? without a user object.
In some cases you might want to have a feature activated for a random set of
users. It can come specially handy when using Rollout for split tests.
$rollout = Rollout.new($redis, randomize_percentage: true)
When on randomize_percentage will make sure that 50% of users for feature A
are selected independently from users for feature B.
Global actions
While groups can come in handy, the actual global setter for a feature does not require a group to be passed.
$rollout.activate(:chat)
In that case you can check the global availability of a feature using the following
$rollout.active?(:chat)
And if something is wrong you can set a feature off for everybody using
Deactivate everybody at once:
$rollout.deactivate(:chat)
For many of our features, we keep track of error rates using redis, and
deactivate them automatically when a threshold is reached to prevent service
failures from cascading. See https://github.com/jamesgolick/degrade for the
failure detection code.
Namespacing
Rollout separates its keys from other keys in the data store using the
"feature" keyspace.
If you're using redis, you can namespace keys further to support multiple
environments by using the
redis-namespace gem.
$ns = Redis::Namespace.new(Rails.env, redis: $redis)
$rollout = Rollout.new($ns)
$rollout.activate_group(:chat, :all)
This example would use the "development:feature:chat:groups" key.
Frontend / UI
Implementations in other languages
- Python: https://github.com/asenchi/proclaim
- PHP: https://github.com/opensoft/rollout
- Clojure: https://github.com/yeller/shoutout
- Perl: https://metacpan.org/pod/Toggle
Contributors
- James Golick - Creator - https://github.com/jamesgolick
- Eric Rafaloff - Maintainer - https://github.com/EricR
Copyright
Copyright (c) 2010-InfinityAndBeyond BitLove, Inc. See LICENSE for details.