# Installing packages with a Gemfile on Elastic Beanstalk

To use RubyGems to install packages that your application requires, include a `Gemfile` file in the root of your project source.
**Example Gemfile** 
```
source "https://rubygems.org"
gem 'sinatra'
gem 'json'
gem 'rack-parser'
```
When a `Gemfile` file is present, Elastic Beanstalk runs `bundle install` to install dependencies. For more information, see the [Gemfiles](https://bundler.io/man/gemfile.5.html) and [Bundle](https://bundler.io/man/bundle.1.html) pages on the Bundler.io website.
**Note** 
You can use a different version of Puma besides the default that's pre-installed with the Ruby platform. To do so, include an entry in a `Gemfile` that specifies the version. You can also specify a different application server, such as Passenger, by using a customized `Gemfile`. 
For both of these cases you're required to configure a `Procfile` to start the application server. 
For more information see *[Configuring the application process with a Procfile](https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/ruby-platform-procfile.html)**.* </div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/ruby-platform-gemfile.md">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/ruby-platform-gemfile.md" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>