# Installing packages with a Gemfile on Elastic Beanstalk
<a name="ruby-platform-gemfile"></a>

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)**.*