Keycloak-Rails-Api

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

gem "keycloak-api-rails", "0.12.4"

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).

• 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.

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 Keycloak::authentication and calling keycloak_authenticate, for example in a before_action, like so:

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

  before_action :keycloak_authenticate
end

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

• keycloak:keycloak_id
• keycloak:roles

They can be accessed using Keycloak::Helper methods.

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

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

Keycloak.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:

Keycloak.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.

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

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

class AuthenticatedController < ApplicationController

  def user
    keycloak_id = Keycloak::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 Keycloak::Authentication

  before_action :keycloak_authenticate, only: show

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

  def index 
    # unauthenticated
  end
end

Keycloak::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
    Keycloak::Helper.current_user_roles(request.env)
  end
end

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

def example
  Keycloak::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.

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

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

If you want to write controller tests in your codebase and that Keycloak is configured for these controllers, here is how to mock it. These lines are based on tests written using rspec.

• First, create a private key. This key should be created once per test suite for performance matters.

config.before(:suite) do
  $private_key = OpenSSL::PKey::RSA.generate(1024)
end

• Then, in a shared_context, configure a lazy token based on your main user. (here, we assume you have a user variable with a keycloak_id property)

let(:jwt) do
  claims = {
    iat: Time.zone.now.to_i,
    exp: (Time.zone.now + 1.day).to_i,
    sub: user.keycloak_id,
  }
  token = JSON::JWT.new(claims)
  token.kid = "default"
  token.sign($private_key, :RS256).to_s
end

• Finally, in the same shared_context, stub Keycloak.public_key_resolver to use a valid public key that is able to validate jwt:

before(:each) do
  public_key_resolver = Keycloak.public_key_resolver
  allow(public_key_resolver).to receive(:find_public_keys) { JSON::JWK::Set.new(JSON::JWK.new($private_key, kid: "default")) }
end

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

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