Add authentication to your Ruby application

tip:

• The following demonstration is built on Ruby 3.3.3.
• The sample project is available in the GitHub repository.

Prerequisites

• A Logto Cloud account or a self-hosted Logto.
• A Logto traditional web application created.

Installation

Install Logto SDK via bundler:

bundle add logto

Or whatever your preferred method of adding gems is.

Integration

note:

The following demonstration is for Ruby on Rails. However, you can apply the same steps to other Ruby frameworks.

Initialize Logto client

In the file where you want to initialize the Logto client (e.g. a base controller or a middleware), add the following code:

require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    endpoint: "https://your-logto-endpoint.com",
    app_id: "your-logto-app-id",
    app_secret: "your-logto-app-secret"
  ),
  navigate: ->(uri) { a_redirect_method(uri) },
  storage: LogtoClient::SessionStorage.new(the_session_object)
)
end

For instance, in a Rails controller, the code might look like this:

app/controllers/sample_controller.rb

require "logto/client"

class SampleController < ApplicationController
  before_action :initialize_logto_client

  private

  def initialize_logto_client
    @client = LogtoClient.new(
      config: LogtoClient::Config.new(
        # ...your configuration
      ),
      # Allow the client to redirect to other hosts (i.e. your Logto tenant)
      navigate: ->(uri) { redirect_to(uri, allow_other_host: true) },
      # Controller has access to the session object
      storage: LogtoClient::SessionStorage.new(session)
    )
  end
end

Configure redirect URIs

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

---

note:

In the following code snippets, we assume your app is running on http://localhost:3000/.

Configure redirect URIs

Switch to the application details page of Logto Console. Add a redirect URI http://localhost:3000/callback.

Just like signing in, users should be redirected to Logto for signing out of the shared session. Once finished, it would be great to redirect the user back to your website. For example, add http://localhost:3000/ as the post sign-out redirect URI section.

Then click "Save" to save the changes.

Handle the callback

Since the redirect URI has been set to http://localhost:3000/callback, it needs to be handled it in our application. In a Rails controller, you can add the following code:

app/controllers/sample_controller.rb

class SampleController < ApplicationController
  def callback
    @client.handle_sign_in_callback(url: request.original_url)
  end
end

And configure the route in config/routes.rb:

config/routes.rb

Rails.application.routes.draw do
  get "/callback", to: "sample#callback"
end

Invoke sign-in and sign-out

There are various ways to invoke sign-in and sign-out in your application. For example, you can implement two routes in your Rails application:

app/controllers/sample_controller.rb

class SampleController < ApplicationController
  def sign_in
    @client.sign_in(redirect_uri: request.base_url + "/callback")
  end

  def sign_out
    @client.sign_out(post_logout_redirect_uri: request.base_url)
  end

  # ...
end

config/routes.rb

Rails.application.routes.draw do
  get "/sign_in", to: "sample#sign_in"
  get "/sign_out", to: "sample#sign_out"

  # ...
end

Then you can create buttons or links in your views to trigger these actions. For example:

app/views/sample/index.html.erb

<% if @client.is_authenticated? %>
  <a href="<%= sign_out_path %>">Sign out</a>
<% else %>
  <a href="<%= sign_in_path %>">Sign in</a>
<% end %>

Checkpoint: Test your application

Now, you can test your application:

1. Run your application, you will see the sign-in button.
2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
3. After you signed in, you will be redirected back to your application and see the sign-out button.
4. Click the sign-out button to clear local storage and sign out.

Get user information

Display user information

To display the user's information, you can use the @client.id_token_claims method. For example, in a view:

app/views/sample/index.html.erb

<% if @client.is_authenticated? %>
  <p>Welcome, <%= @client.id_token_claims["name"] %></p>
<% else %>
  <p>Please sign in</p>
<% end %>

Please refer to the #id_token_claims method in the gemdocs for more information.

Request additional claims

You may find some user information are missing in the returned object from id_token_claims. This is because OAuth 2.0 and OpenID Connect (OIDC) are designed to follow the principle of least privilege (PoLP), and Logto is built on top of these standards.

By default, limited claims are returned. If you need more information, you can request additional scopes to access more claims.

info:

A "claim" is an assertion made about a subject; a "scope" is a group of claims. In the current case, a claim is a piece of information about the user.

Here's a non-normative example the scope - claim relationship:

tip:

The "sub" claim means "subject", which is the unique identifier of the user (i.e. user ID).

Logto SDK will always request three scopes: openid, profile, and offline_access.

To request additional scopes, you can configure the scopes option in the LogtoClient::Config object:

require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    # ...other configurations
    scopes: ["email", "phone"] # Add more scopes as needed
  ),
  # ...other configurations
)

Then you can access the additional claims via id_token_claims:

app/views/sample/index.html.erb

<% if @client.is_authenticated? %>
  <p>Name: <%= @client.id_token_claims["name"] %></p>
  <p>Email: <%= @client.id_token_claims["email"] %></p>
  <p>Phone: <%= @client.id_token_claims["phone"] %></p>
<% else %>
  <p>Please sign in</p>
<% end %>

Claims that need network requests

To prevent bloating the ID token, some claims require network requests to fetch. For example, the custom_data claim is not included in the user object even if it's requested in the scopes. To access these claims, you can use the fetch_user_info method:

app/views/sample/index.html.erb

<% if @client.is_authenticated? %>
<p>Custom data: <%= @client.fetch_user_info["custom_data"] %></p>
<!-- ... -->

This method will fetch the user information by requesting to the userinfo endpoint. To learn more about the available scopes and claims, see the Scopes and claims section.

Scopes and claims

Logto uses OIDC scopes and claims conventions to define the scopes and claims for retrieving user information from the ID token and OIDC userinfo endpoint. Both of the "scope" and the "claim" are terms from the OAuth 2.0 and OpenID Connect (OIDC) specifications.

Here's the list of supported scopes and the corresponding claims:

openid

Claim name	Type	Description	Needs userinfo?
sub	string	The unique identifier of the user	No

profile

Claim name	Type	Description	Needs userinfo?
name	string	The full name of the user	No
username	string	The username of the user	No
picture	string	URL of the End-User's profile picture. This URL MUST refer to an image file (for example, a PNG, JPEG, or GIF image file), rather than to a Web page containing an image. Note that this URL SHOULD specifically reference a profile photo of the End-User suitable for displaying when describing the End-User, rather than an arbitrary photo taken by the End-User.	No
created_at	number	Time the End-User was created. The time is represented as the number of milliseconds since the Unix epoch (1970-01-01T00:00:00Z).	No
updated_at	number	Time the End-User's information was last updated. The time is represented as the number of milliseconds since the Unix epoch (1970-01-01T00:00:00Z).	No

Other standard claims include family_name, given_name, middle_name, nickname, preferred_username, profile, website, gender, birthdate, zoneinfo, and locale will be also included in the profile scope without the need for requesting the userinfo endpoint. A difference compared to the claims above is that these claims will only be returned when their values are not empty, while the claims above will return null if the values are empty.

note:

Unlike the standard claims, the created_at and updated_at claims are using milliseconds instead of seconds.

email

Claim name	Type	Description	Needs userinfo?
email	string	The email address of the user	No
email_verified	boolean	Whether the email address has been verified	No

phone

Claim name	Type	Description	Needs userinfo?
phone_number	string	The phone number of the user	No
phone_number_verified	boolean	Whether the phone number has been verified	No

address

Please refer to the OpenID Connect Core 1.0 for the details of the address claim.

custom_data

Claim name	Type	Description	Needs userinfo?
custom_data	object	The custom data of the user	Yes

identities

Claim name	Type	Description	Needs userinfo?
identities	object	The linked identities of the user	Yes
sso_identities	array	The linked SSO identities of the user	Yes

urn:logto:scope:organizations

Claim name	Type	Description	Needs userinfo?
organizations	string[]	The organization IDs the user belongs to	No
organization_data	object[]	The organization data the user belongs to	Yes

urn:logto:scope:organization_roles

Claim name	Type	Description	Needs userinfo?
organization_roles	string[]	The organization roles the user belongs to with the format of <organization_id>:<role_name>	No

---

Considering performance and the data size, if "Needs userinfo?" is "Yes", it means the claim will not show up in the ID token, but will be returned in the userinfo endpoint response.

API resources and organizations

We recommend to read 🔐 Role-Based Access Control (RBAC) first to understand the basic concepts of Logto RBAC and how to set up API resources properly.

Configure Logto client

Once you have set up the API resources, you can add them when configuring Logto in your app:

require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    # ...other configurations
    resources: ["https://shopping.your-app.com/api", "https://store.your-app.com/api"] # Add API resources
  ),
  # ...other configurations
)

Each API resource has its own permissions (scopes).

For example, the https://shopping.your-app.com/api resource has the shopping:read and shopping:write permissions, and the https://store.your-app.com/api resource has the store:read and store:write permissions.

To request these permissions, you can add them when configuring Logto in your app:

require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    # ...other configurations
    scopes: ["shopping:read", "shopping:write", "store:read", "store:write"],
    resources: ["https://shopping.your-app.com/api", "https://store.your-app.com/api"]
  ),
  # ...other configurations
)

You may notice that scopes are defined separately from API resources. This is because Resource Indicators for OAuth 2.0 specifies the final scopes for the request will be the cartesian product of all the scopes at all the target services.

Thus, in the above case, scopes can be simplified from the definition in Logto, both of the API resources can have read and write scopes without the prefix. Then, in the Logto config:

require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    # ...other configurations
    scopes: ["read", "write"],
    resources: ["https://shopping.your-app.com/api", "https://store.your-app.com/api"]
  ),
  # ...other configurations
)

For every API resource, it will request for both read and write scopes.

note:

It is fine to request scopes that are not defined in the API resources. For example, you can request the email scope even if the API resources don't have the email scope available. Unavailable scopes will be safely ignored.

After the successful sign-in, Logto will issue proper scopes to API resources according to the user's roles.

Fetch access token for the API resource

To fetch the access token for a specific API resource, you can use the access_tpken method:

token = @client.access_token(resource: "https://shopping.your-app.com/api")

This method will return a JWT access token that can be used to access the API resource when the user has related permissions. If the current cached access token has expired, this method will automatically try to use a refresh token to get a new access token.

Fetch organization tokens

If organization is new to you, please read 🏢 Organizations (Multi-tenancy) to get started.

You need to add LogtoCore::USER_SCOPE[:organizations] scope when configuring the Logto client:

require "logto/core"
require "logto/client"

@client = LogtoClient.new(
  config: LogtoClient::Config.new(
    # ...other configurations
    scopes: [LogtoCore::USER_SCOPE[:organizations]]
  ),
  # ...other configurations
)

Once the user is signed in, you can fetch the organization token for the user:

token = @client.access_token(organization_id: "organization_id")

Organization API resources

To fetch an access token for an API resource in an organization, you can use the access_token method with both the API resource and organization ID as parameters:

token = @client.access_token(
  api_resource: "https://shopping.your-app.com/api",
  organization_id: "organization_id"
)

Further readings

End-user flows: authentication flows, account flows, and organization flows Configure connectors Protect your API