In the Rollouts interface, navigate to 'Features &gt; Create New Feature' and create a feature flag called 'hello_world':</p>\n<p><img src=https://www.optimizely.com/"https://raw.githubusercontent.com/optimizely/labs/master/assets/optimizely-screenshots/create-flag.gif/" alt=\"Screenshot\" /></p>\n<p>To connect your 'hello_world' feature to your application, find your SDK Key. Navigate to the far left 'Settings' &gt; 'Environments' and copy the Development SDK Key value.</p>\n<p><img src=https://www.optimizely.com/"https://raw.githubusercontent.com/optimizely/labs/master/assets/optimizely-screenshots/sdk-key.gif/" alt=\"Screenshot\" /></p>\n<h3>3. Install the Optimizely Rollouts Ruby SDK</h3>\n<p>The Ruby SDK allows you to setup feature toggles from within your codebase.</p>\n<p>Install the Optimizely gem from the command-line with:</p>\n<pre><code>gem install optimizely-sdk\n</code></pre>\n<p>Create a new file <code>optly.rb</code> in the root of your new application. If you followed the Sinatra instructions above, the <code>optly.rb</code> file should be in the same directory as <code>myapp.rb</code></p>\n<p>Import the SDK and initialize a singleton instance of the <a href=https://www.optimizely.com/"https://github.com/optimizely/ruby-sdk/">Optimizely SDK</a> by placing the following code in your new <code>optly.rb</code> file (be sure to replace &lt;Your_SDK_Key&gt; with your actual SDK key):</p>\n<pre><code class=\"language-ruby\"># optly.rb\nrequire 'singleton'\nrequire 'logger'\nrequire 'optimizely/optimizely_factory'\n\nclass Optly\n include Singleton\n\n def initialize\n sdk_key = '&lt;Your_SDK_Key&gt;'\n\n logger = Optimizely::SimpleLogger.new(Logger::INFO)\n\n config_manager = Optimizely::HTTPProjectConfigManager.new(\n sdk_key: sdk_key,\n polling_interval: 10,\n blocking_timeout: 10,\n logger: logger,\n )\n\n @client = Optimizely::OptimizelyFactory.custom_instance(\n sdk_key, # sdk_key\n nil, # datafile\n nil, # event_dispatcher\n logger, # logger\n nil, # error_handler\n false, # skip_json_validation\n nil, # user_profile_service\n config_manager, # config_manager\n nil # notification_center\n )\n end\n\n def client\n @client\n end\nend\n</code></pre>\n<p>A singleton as we defined it above allows you to use Optimizely anywhere within your Ruby application you want.</p>\n<p>Require the Optimizely singleton instance in your Ruby application by adding <code>require './optly'</code> in <code>myapp.rb</code>:</p>\n<pre><code class=\"language-ruby\"># myapp.rb\nrequire 'sinatra'\nrequire './optly' # Imports the Optimizely singleton\n\nget '/' do\n 'Hello world!'\nend\n</code></pre>\n<h3>4. Implement the Feature Flag</h3>\n<p>To implement your 'hello_world' feature flag, use the is_feature_enabled method on the optimizely client instance:</p>\n<pre><code class=\"language-ruby\"> enabled = Optly.instance.client.is_feature_enabled('hello_world', 'user123', {\n 'customerId' =&gt; 123,\n 'isVIP' =&gt; true\n })\n\n enabled ? 'Hello World! You got the hello_world feature!' : 'You did not get the hello_world feature'\n</code></pre>\n<p>Note that <code>is_feature_enabled</code> takes three parameters. The first is used to identify the feature you created in the Optimizely application. The next two are associated with visitors to your application:</p>\n<ul>\n<li><strong>userId</strong>: a string used for random percentage rollouts across your users. This can be any string that uniquely identifies a particular user. In this case, <code>user123</code> is just a hard-coded example of what might come from your user table database.</li>\n<li><strong>userAttributes</strong>: a hash of key, value attributes used for targeting rollouts across your users. In this case,\n<code>customerId</code> and <code>isVIP</code> are just examples.</li>\n</ul>\n<p>To read more about the API and its parameters, see <a href=https://www.optimizely.com/"https://docs.developers.optimizely.com/full-stack/docs/is-feature-enabled-ruby#section-parameters\">this documentation page</a>.</p>\n<p>Your full code in <code>myapp.rb</code> should look like the following:</p>\n<pre><code class=\"language-ruby\"># myapp.rb\nrequire 'sinatra'\nrequire './optly'\n\nget '/' do\n enabled = Optly.instance.client.is_feature_enabled('hello_world', 'user123', {\n 'customerId' =&gt; 123,\n 'isVIP' =&gt; true\n })\n\n enabled ? 'Hello World! You got the hello_world feature!' : 'You did not get the hello_world feature'\nend\n</code></pre>\n<h3>5. Turn the Feature Toggle on!</h3>\n<p>If you save and re-run your application now, you'll notice that you did not get the feature. This is because the feature is not enabled, which means it's off for all visitors to your application.</p>\n<p>To turn on the feature:</p>\n<ol>\n<li>Log-in to the Optimizely project where you made your hello_world feature</li>\n<li>Navigate to Features</li>\n<li>Click on the 'hello_world' feature</li>\n<li>Change to the 'Development' environment to match the SDK Key we used</li>\n<li>Roll the feature out to ensure it is set to 100% for everyone</li>\n<li>Click Save to save your changes</li>\n</ol>\n<p><img src=https://www.optimizely.com/"https://raw.githubusercontent.com/optimizely/labs/master/assets/optimizely-screenshots/flag-rollout-dev.gif/" alt=\"Screenshot\" /></p>\n<p>In less than 1 min, refreshing your Ruby app should now show the feature toggled on and you should see &quot;Hello world! You got the hello_world feature!&quot;.</p>\n<p>Congrats! You've implemented a feature flag in a Ruby Sinatra application. Hope you've enjoyed this lab!</p>\n","labels":"full stack, ruby, sinatra, feature flags","revisionDate":"2020-07-09","resourceFile":null,"resourceFileName":null,"author":null,"repositoryUrl":"https://raw.githubusercontent.com/optimizely/labs/master/labs/feature-flags-ruby-sinatra/README.md","labelsLabel":"Labels","publishedLabel":"Published","resourcesLabel":"Resources","repositoryLabel":"Repository","authorLabel":"Author"}" data-redux="false" data-router="false">

# myapp.rb
require 'sinatra'

get '/' do
  'Hello world!'
end

gem install sinatra

ruby myapp.rb

gem install optimizely-sdk

# optly.rb
require 'singleton'
require 'logger'
require 'optimizely/optimizely_factory'

class Optly
  include Singleton

  def initialize
    sdk_key = '<Your_SDK_Key>'

    logger = Optimizely::SimpleLogger.new(Logger::INFO)

    config_manager = Optimizely::HTTPProjectConfigManager.new(
      sdk_key: sdk_key,
      polling_interval: 10,
      blocking_timeout: 10,
      logger: logger,
    )

    @client = Optimizely::OptimizelyFactory.custom_instance(
      sdk_key,          # sdk_key
      nil,              # datafile
      nil,              # event_dispatcher
      logger,           # logger
      nil,              # error_handler
      false,            # skip_json_validation
      nil,              # user_profile_service
      config_manager,   # config_manager
      nil               # notification_center
    )
  end

  def client
    @client
  end
end

# myapp.rb
require 'sinatra'
require './optly' # Imports the Optimizely singleton

get '/' do
  'Hello world!'
end

  enabled = Optly.instance.client.is_feature_enabled('hello_world', 'user123', {
    'customerId' => 123,
    'isVIP' =>  true
  })

  enabled ? 'Hello World! You got the hello_world feature!' : 'You did not get the hello_world feature'

# myapp.rb
require 'sinatra'
require './optly'

get '/' do
  enabled = Optly.instance.client.is_feature_enabled('hello_world', 'user123', {
    'customerId' => 123,
    'isVIP' =>  true
  })

  enabled ? 'Hello World! You got the hello_world feature!' : 'You did not get the hello_world feature'
end