Welcome to the quickstart guide for Optimizely's Ruby SDK. The instructions below will help you implement Rollouts and launch your first feature flag.

This guide will help you:

1. Install the SDK
2. Instantiate Optimizely when your app starts
3. Create a feature flag
4. Roll out a feature

The gem for the Ruby SDK is distributed through RubyGems. To install, use gem install optimizely-sdk or bundler to install the gem optimizely-sdk.

The full source code is at https://github.com/optimizely/ruby-sdk.

The datafile stores the configuration for all your features and rollouts. Whenever you make a change in Optimizely, the datafile is automatically updated so you can pull configuration changes down into your application.

The sample below shows how you can get a local copy of the datafile from our server and instantiate a client with it. Later, you'll want to adjust this code to handle datafile updates.

require 'optimizely'
require 'httparty'

url = 'https://cdn.optimizely.com/datafiles/<Your_SDK_Key>.json'
datafile = HTTParty.get(url).body
optimizely_client = Optimizely::Project.new(datafile)

Here's where to find your SDK Key:

1. Navigate to Settings > Environments.
2. Copy the SDK Key / Primary URL.

Choose a feature in your app to turn on and off with a feature flag. For your first flag, consider starting with a link or visual element that's simple to change, show, or hide based on a Boolean.

To set up your first feature flag, navigate to Features > Create New Feature.

Here's how to set it up:

After saving, use the Boolean Is Feature Enabled method to show, hide, or change some visual part of your application. You should see a value of false from this function because you haven't rolled out the feature yet. You'll turn it on in the next step.

# Evaluate a feature flag and a variable
enabled = optimizely_client.is_feature_enabled('new_feature', 'user123')

In Optimizely, navigate back to Features and select your feature flag.

You'll return to this feature whenever you want to update the feature flag. For example, roll out your feature incrementally by moving the slider up by 10% per day or show it to a certain group of users. Move it to 100% for a big reveal, or 0% if issues arise in production. No code deployment necessary.

A basic way to confirm that your feature flag is working:

Show the feature to yourself

1. Navigate to your feature.
2. Toggle it ON and move the slider to 100% traffic. Click Save.
3. Confirm that you see the feature.

Hide the feature from yourself

1. Navigate back to the feature.
2. Toggle it OFF. Click Save.
3. Confirm that you no longer see the feature.

When you're ready, go ahead and launch your feature. Come back and change its configuration any time, without deploying code.