# Sinatra integration

The Clerk Ruby SDK provides a seamless integration with Sinatra through a dedicated extension that gives you access to authentication, user management, and Organization management features.

1. ## Install `clerk-sdk-ruby`

   The [Clerk Ruby SDK](https://clerk.com/docs/reference/ruby/overview.md) provides a range of backend utilities to simplify user authentication and management in your application.

   1. Add the following code to your application's `Gemfile`.

      filename: Gemfile
      ```ruby
      gem 'clerk-sdk-ruby', require: "clerk"
      ```
   2. Run the following command to install the SDK:

      filename: terminal
      ```sh
      bundle install
      ```
2. ## Configuration

   The configuration object provides a flexible way to configure the SDK. When a configuration value is not explicitly provided, it will fall back to checking the corresponding [environment variable](https://clerk.com/docs/reference/ruby/overview.md#available-environment-variables). You must provide your Clerk Secret Key.

   The following example shows how to set up your configuration object:

   ```ruby
   Clerk.configure do |c|
     c.secret_key = `{{secret}}` # if omitted: ENV["CLERK_SECRET_KEY"] - API calls will fail if unset
     c.logger = Logger.new(STDOUT) # if omitted, no logging
   end
   ```

   For more information, see [Faraday's documentation](https://lostisland.github.io/faraday/#/).
3. ## Add Clerk's Sinatra extension

   The `clerk` object provides access to the [Ruby SDK's available methods](https://clerk.com/docs/reference/ruby/overview.md#available-methods). To get access to the `clerk` object, you must `register` the `Sinatra::Clerk` extension.

   The following example demonstrates how to register the `Sinatra::Clerk` extension and access the user's [`User`](https://github.com/clerk/clerk-sdk-ruby/blob/main/docs/models/components/user.md) object.

   filename: app.rb

   ```ruby
   require "clerk/sinatra"
   require "sinatra/base"

   class App < Sinatra::Base
     register Sinatra::Clerk

     # Access the user's `User` object
     get "/" do
       @user = clerk.user
       erb :index, format: :html5
     end

     run! if app_file == $0
   end
   ```

## Example: Protect routes

The `auth` filter can be added to any route to protect it from unauthenticated users. If a user is not authenticated, by default, `auth` will redirect them to the sign-in page.

```ruby
require "clerk/sinatra"
require "sinatra/base"

class App < Sinatra::Base
  register Sinatra::Clerk

  get "/" do
    erb :index, format: :html5
  end

  # Protect the "/admin" route with the `auth` filter
  # If the user is not authenticated, they will be redirected to the sign-in page
  get "/admin", auth: true do
    @user = clerk.user
    erb :admin, format: :html5
  end

  run! if app_file == $0
end
```

### Override the default behavior of the `auth` filter

By default, the `auth` filter will redirect to the sign-in page if the user is not authenticated. You can override this behavior by using `set(:auth)`.

In the following example, the `auth` filter is overridden to redirect to the homepage if the user is not authenticated.

filename: app.rb
```ruby
require "clerk/sinatra"
require "sinatra/base"

class App < Sinatra::Base
  register Sinatra::Clerk

  # Set `auth` to perform custom behavior
  set(:auth) do |active|
    condition do
      # If the user is not authenticated, redirect to the homepage
      if active && !clerk.session
        puts "User is not authenticated, redirecting to the homepage"
        redirect '/'
      end
    end
  end

  get "/" do
    erb :index, format: :html5
  end

  # Protect the "/admin" route with the `auth` filter
  # which will perform the custom behavior set in `set(:auth)`
  get "/admin", auth: true do
    @user = clerk.user
    erb :admin, format: :html5
  end

  run! if app_file == $0
end
```

## Example: Reverification

For actions requiring additional security, Clerk provides a `reverify` filter that prompts users to re-authenticate. This filter accepts an optional [preset](https://clerk.com/docs/reference/ruby/overview.md#reverification) parameter to customize the reverification requirements.

In the following example, the `/super-secret-admin` or `/chill-admin` routes will be protected from unauthenticated users. If the user is authenticated, they will be required to reverify their session, depending on when they last verified their session.

```ruby
require "clerk/sinatra"
require "sinatra/base"

class App < Sinatra::Base
  register Sinatra::Clerk

  get "/" do
    erb :index, format: :html5
  end

  # Protect the "/super-secret-admin" route with the `auth` and `reverify` filters
  # Reverification preset defaults to `STRICT`
  post "/super-secret-admin", auth: true, reverify: true do
    {message: clerk.user? ? "Valid session" : "Not signed in"}.to_json
  end

  # Protect the "/chill-admin" route with the `auth` and `reverify` filters
  # Reverification preset is set to `LAX`
  post "/chill-admin", auth: true, reverify: Clerk::StepUp::Preset::LAX do
    {message: clerk.user? ? "Valid session" : "Not signed in"}.to_json
  end

  run! if app_file == $0
end
```

---

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