Keycloak-Rails-Api

This gem validates Keycloak JWT token for Ruby On Rails APIs.

Requirements

• Ruby >= 2.7
• Rails >= 4.2

Every push is tested against Ruby 2.7, 3.0, 3.1, 3.2, 3.3, 3.4 and 4.0. Each of them installs the most recent dependencies it supports, so the test suite runs against Rails 7.1 (Ruby 2.7 and 3.0), Rails 7.2 (Ruby 3.1) and Rails 8.1 (Ruby 3.2 and above).

Ruby 2.7 and 3.0 reached their end of life and no longer receive security fixes. They are supported here so that applications running on Rails 7.0 and 7.1 can use this gem, but upgrading Ruby remains the recommended path.

Install

gem "keycloak-api-rails", "1.1.1"

Token validation

Tokens sent (through query strings or Authorization headers) are validated against a Keycloak public key. This public key is downloaded every day by default (this interval can be changed through public_key_cache_ttl).

Pass token to the API

• Method 1: By adding an Authorization HTTP Header with its value set to Bearer <your token>. e.g using curl: curl -H "Authorization: Bearer <your-token>" https://api.pouet.io/api/more-pouets
• Method 2: By providing the token via query string, especially via the parameter named authorizationToken. Keep in mind that this method is less secure (url are kept intact in your browser history, and so on...) e.g. using curl: curl https://api.pouet.io/api/more-pouets?authorizationToken<your-token>

If both method are used at the same time, The query string as a higher priority when reading given tokens.

Opt-in vs. Opt-out validation

By default, Keycloak-api-rails installs as a Rack Middleware. It processes all requests before any application logic. URIs/Paths can be excluded (opted-out) from this validation using the 'skip_paths' config option

Alternatively, it can be configured to opt-in to validation. In this case, no Rack middleware is used, and controllers can request (opt-in) by including the module KeycloakApiRails::authentication and calling keycloak_authenticate, for example in a before_action, like so:

class MyApiController < ActionController::Base
  include KeycloakApiRails::Authentication

  before_action :keycloak_authenticate
end

When a token is validated

In Rails controller, the request env variables has two more properties:

• keycloak:keycloak_id
• keycloak:roles

They can be accessed using KeycloakApiRails::Helper methods.

Overall configuration options

All options have a default value. However, all of them can be changed in your initializer file.

Option	Default Value	Type	Required?	Description	Example
server_url	nil	String	Required	The base url where your Keycloak server is located. This value can be retrieved in your Keycloak client configuration.	auth:8080
realm_id	nil	String	Required	Realm's name (not id, actually)	master
logger	Logger.new(STDOUT)	Logger	Optional	The logger used by keycloak-api-rails	Rails.logger
skip_paths	{}	Hash of methods and paths regexp	Optional	Paths whose the token must not be validatefd	{ get: [/^\/health\/.+/] }
opt_in	false	Boolean	Optional	When true, All requests will be validated (excluding requests matching skip_paths). When false, validation must be explicitly requested	true
token_expiration_tolerance_in_seconds	10	Logger	Optional	Number of seconds a token can expire before being rejected by the API.	15
public_key_cache_ttl	86400	Integer	Optional	Amount of time, in seconds, specifying maximum interval between two requests to project_name to retrieve new public keys. It is 86400 seconds (1 day) by default. At least once per this configured interval (1 day by default) will be new public key always downloaded.	Rails.logger
custom_attributes	[]	Array Of String	Optional	List of token attributes to read from each token and to add to their http request env	["originalFirstName", "originalLastName"]
ca_certificate_file	nil	String	Optional	Path to the certificate authority used to validate the Keycloak server certificate	/credentials/production_root_ca_cert.pem

Configure it

Create a keycloak.rb file in your Rails config/initializers folder. For instance:

KeycloakApiRails.configure do |config|
  config.server_url = ENV["KEYCLOAK_SERVER_URL"]
  config.realm_id   = ENV["KEYCLOAK_REALM_ID"]
  config.logger     = Rails.logger
  config.skip_paths = {
    post:   [/^\/message/],
    get:    [/^\/locales/, /^\/health\/.+/]
  }
end

Or using opt-in configuration:

KeycloakApiRails.configure do |config|
  config.server_url = ENV["KEYCLOAK_SERVER_URL"]
  config.realm_id   = ENV["KEYCLOAK_REALM_ID"]
  config.logger     = Rails.logger
  config.opt_in     = true
end

When using opt-in is true, skip_paths is not used.

Use cases

Once this gem is configured in your Rails project, you can read, validate and use tokens in your controllers.

Keycloak Id

If you identify users using their Keycloak Id, this value can be read from your controllers using KeycloakApiRails::Helper.current_user_id(request.env).

class AuthenticatedController < ApplicationController

  def user
    keycloak_id = KeycloakApiRails::Helper.current_user_id(request.env)
    User.active.find_by(keycloak_id: keycloak_id)
  end
end

Or if using opt-in mode, the controller can request validation conditionally:

class MostlyAuthenticatedController < ApplicationController
  include KeycloakApiRails::Authentication

  before_action :keycloak_authenticate, only: show

  def show
    keycloak_id = KeycloakApiRails::Helper.current_user_id(request.env)
    User.active.find_by(keycloak_id: keycloak_id)
  end

  def index 
    # unauthenticated
  end
end

Roles

KeycloakApiRails::Helper.current_user_roles can be use against a Rails request to read user's roles.

For example, a controller can require users to be administrator (considering you defined an application-admin role):

class AdminController < ApplicationController

  before_action :require_to_be_admin!

  def require_to_be_admin!
    if !current_user_roles.include?("application-admin")
      render(json: { reason: "admin", message: "You have to be an administrator to access that endpoint." }, status: :forbidden)
    end
  end

  private

  def current_user_roles
    KeycloakApiRails::Helper.current_user_roles(request.env)
  end
end

Create an URL where the token must be passed via query string

KeycloakApiRails::Helper.create_url_with_token method can be used to build an url from another, by adding a token as query string.

def example
  KeycloakApiRails::Helper.create_url_with_token("https://api.pouet.io/api/more-pouets", "myToken")
end

This should output https://api.pouet.io/api/more-pouets?authorizationToken=myToken.

Accessing Keycloak Service

A lazy-loaded service KeycloakApiRails::Service can be accessed using KeycloakApiRails.service. For instance, to read a provided token:

class RenderTokenController < ApplicationController
  def show
    uri     = request.env["REQUEST_URI"]
    headers = request.env
    token   = KeycloakApiRails.service.read_token(uri, headers)
    render json: { token: token }, status: :ok
  end
end

Writing integration tests

If you want to write controller or request tests in your codebase and that Keycloak is configured for these controllers, this gem provides the helpers that forge valid tokens, so that no Keycloak server is required. These helpers are not loaded by keycloak-api-rails: they have to be required explicitly, so that nothing they define ends up in a production process. These lines are based on tests written using rspec.

# spec/rails_helper.rb
require "keycloak-api-rails/testing"

RSpec.configure do |config|
  config.include KeycloakApiRails::Testing::Helpers
  config.before(:suite) { KeycloakApiRails::Testing.stub_public_keys! }
end

stub_public_keys! makes the library validate the tokens forged by these helpers, instead of fetching public keys from a Keycloak server. server_url and realm_id therefore do not have to be configured in the test environment. Requests can then be authenticated with:

it "returns the current user" do
  get "/me", headers: keycloak_auth_headers(sub: user.keycloak_id)

  expect(response).to have_http_status(:ok)
end

keycloak_auth_headers returns an Authorization header, and keycloak_token returns the token alone. Both accept the same optional parameters, one for each claim this library reads:

Parameter	Claim	Default
sub	sub	a random UUID
email	email	none
locale	locale	none
authorized_party	azp	none
roles	realm_access.roles	none
resource_roles	resource_access	none
issued_at	iat	now
expires_at	exp	one hour after issued_at
claims	any other claim	none

For instance, to authenticate a request as a user having the realm role admin, the role reader on the client a-client, and a tenant_id attribute declared in config.custom_attributes:

headers = keycloak_auth_headers(sub:            user.keycloak_id,
                                roles:          ["admin"],
                                resource_roles: { "a-client" => ["reader"] },
                                claims:         { "tenant_id" => tenant.id })

An expired token is forged by passing an expires_at in the past, which is how a 401 can be tested. Assigning KeycloakApiRails.public_key_resolver = nil restores the regular resolver.

How to execute library tests

From the keycloak-rails-api directory:

  $ docker build . -t keycloak-rails-api:test
  $ docker run -v `pwd`:/usr/src/app/ keycloak-rails-api:test bundle exec rspec spec

How to release a new version

Releases are published to RubyGems by GitHub Actions (.github/workflows/release.yml), through Trusted Publishing: no API key is stored in this repository, the workflow exchanges a short-lived GitHub OIDC token for a scoped RubyGems credential.

1. Update KeycloakApiRails::VERSION in lib/keycloak-api-rails/version.rb and the CHANGELOG.md
2. Commit and push these changes to main
3. Tag the commit and push the tag:

  $ git tag -a v1.2.0 -m "Version 1.2.0"
  $ git push origin v1.2.0

The workflow then checks that the tag matches KeycloakApiRails::VERSION, runs the tests, builds the gem and pushes it. It only publishes tags starting with v.

Next developments

• Manage multiple realms
• Avoid duplicate code in KeycloakApiRails::Middleware and KeycloakApiRails::Authentication