rollout

# rollout

Fast feature flags.

Upgrading from Rollout 2? Follow the [Rollout 3 upgrade guide](docs/upgrading-to-v3.md)
before updating your dependencies.

[![Gem Version](https://badge.fury.io/rb/rollout.svg)](https://badge.fury.io/rb/rollout)
[![CI](https://github.com/fetlife/rollout/actions/workflows/test.yml/badge.svg)](https://github.com/fetlife/rollout/actions/workflows/test.yml)
[![Code Climate](https://codeclimate.com/github/FetLife/rollout/badges/gpa.svg)](https://codeclimate.com/github/FetLife/rollout)
[![Test Coverage](https://codeclimate.com/github/FetLife/rollout/badges/coverage.svg)](https://codeclimate.com/github/FetLife/rollout/coverage)

## Install it

```bash
gem install rollout -v '~> 3.1'
gem install rollout-redis-adapter -v '~> 0.1'
```

```ruby
gem "rollout", "~> 3.1"
gem "rollout-redis-adapter", "~> 0.1"
```

Active Record applications can use `rollout-active_record-adapter` instead of
`rollout-redis-adapter`. See the [Active Record adapter README](rollout-active_record-adapter/README.md).
To copy current feature state from Redis, see
[Migrate from Redis](rollout-active_record-adapter/README.md#migrate-from-redis).

## How it works

Initialize a rollout object. I assign it to a global var.

```ruby
require "redis"
require "rollout"
require "rollout-redis-adapter"

$redis = Redis.new
$rollout = Rollout.new(adapter: Rollout::Adapters::Redis.new($redis))
```


Update data specific to a feature:

```ruby
$rollout.set_feature_data(:chat, description: 'foo', release_date: 'bar', whatever: 'baz')
```

Check whether a feature is active for a particular user:

```ruby
$rollout.active?(:chat, User.first) # => true/false
```

Check whether a feature is active globally:

```ruby
$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:

```ruby
$rollout.activate_group(:chat, :all)
```

You might also want to define your own groups. We have one for our caretakers:

```ruby
$rollout.define_group(:caretakers) do |user|
  user.caretaker?
end
```

You can activate multiple groups per feature.

Deactivate groups like this:

```ruby
$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:

```ruby
$rollout.activate_user(:chat, @user)
```

Deactivate them like this:

```ruby
$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.

```ruby
$rollout.activate_percentage(:chat, 20)
```

The algorithm for determining which users get let in is this:

```ruby
Zlib.crc32(user.id.t