class Rails::Application

Parent:
Engine

In Rails 3.0, a Rails::Application object was introduced which is nothing more than an Engine but with the responsibility of coordinating the whole boot process.

Initialization

Rails::Application is responsible for executing all railties and engines initializers. It also executes some bootstrap initializers (check Rails::Application::Bootstrap) and finishing initializers, after all the others are executed (check Rails::Application::Finisher).

Configuration

Besides providing the same configuration as Rails::Engine and Rails::Railtie, the application object has several specific configurations, for example “cache_classes”, “consider_all_requests_local”, “filter_parameters”, “logger” and so forth.

Check Rails::Application::Configuration to see them all.

Routes

The application object is also responsible for holding the routes and reloading routes whenever the files change in development.

Middlewares

The Application is also responsible for building the middleware stack.

Booting process

The application is also responsible for setting up and executing the booting process. From the moment you require “config/application.rb” in your app, the booting process goes like this:

1)  require "config/boot.rb" to setup load paths
2)  require railties and engines
3)  Define Rails.application as "class MyApp::Application < Rails::Application"
4)  Run config.before_configuration callbacks
5)  Load config/environments/ENV.rb
6)  Run config.before_initialize callbacks
7)  Run Railtie#initializer defined by railties, engines and application.
    One by one, each engine sets up its load paths, routes and runs its config/initializers/* files.
8)  Custom Railtie#initializers added by railties, engines and applications are executed
9)  Build the middleware stack and run to_prepare callbacks
10) Run config.before_eager_load and eager_load! if eager_load is true
11) Run config.after_initialize callbacks

Multiple Applications

If you decide to define multiple applications, then the first application that is initialized will be set to Rails.application, unless you override it with a different application.

To create a new application, you can instantiate a new instance of a class that has already been created:

class Application < Rails::Application
end

first_application  = Application.new
second_application = Application.new(config: first_application.config)

In the above example, the configuration from the first application was used to initialize the second application. You can also use the initialize_copy on one of the applications to create a copy of the application which shares the configuration.

If you decide to define rake tasks, runners, or initializers in an application other than Rails.application, then you must run those these manually.

Attributes

assets[RW]
reloaders[R]
sandbox[RW]
sandbox?[RW]

Public Class Methods

create(initial_variable_values = {}, &block) Show source
# File railties/lib/rails/application.rb, line 100
def create(initial_variable_values = {}, &block)
  new(initial_variable_values, &block).run_load_hooks!
end
find_root(from) Show source
# File railties/lib/rails/application.rb, line 104
def find_root(from)
  find_root_with_flag "config.ru", from, Dir.pwd
end
inherited(base) Show source
# File railties/lib/rails/application.rb, line 89
def inherited(base)
  super
  Rails.app_class = base
  add_lib_to_load_path!(find_root(base.called_from))
  ActiveSupport.run_load_hooks(:before_configuration, base)
end
Calls superclass method
instance() Show source
# File railties/lib/rails/application.rb, line 96
def instance
  super.run_load_hooks!
end
Calls superclass method
new(initial_variable_values = {}, &block) Show source
# File railties/lib/rails/application.rb, line 125
def initialize(initial_variable_values = {}, &block)
  super()
  @initialized       = false
  @reloaders         = []
  @routes_reloader   = nil
  @app_env_config    = nil
  @ordered_railties  = nil
  @railties          = nil
  @message_verifiers = {}
  @ran_load_hooks    = false

  # are these actually used?
  @initial_variable_values = initial_variable_values
  @block = block
end
Calls superclass method

Public Instance Methods

call(env) Show source
# File railties/lib/rails/application.rb, line 162
def call(env)
  env["ORIGINAL_FULLPATH"] = build_original_fullpath(env)
  env["ORIGINAL_SCRIPT_NAME"] = env["SCRIPT_NAME"]
  super(env)
end

Implements call according to the Rack API. It simply dispatches the request to the underlying middleware stack.

Calls superclass method
config_for(name) Show source
# File railties/lib/rails/application.rb, line 227
def config_for(name)
  yaml = Pathname.new("#{paths["config"].existent.first}/#{name}.yml")

  if yaml.exist?
    require "erb"
    (YAML.load(ERB.new(yaml.read).result) || {})[Rails.env] || {}
  else
    raise "Could not load configuration. No such file - #{yaml}"
  end
rescue Psych::SyntaxError => e
  raise "YAML syntax error occurred while parsing #{yaml}. "          "Please note that YAML must be consistently indented using spaces. Tabs are not allowed. "          "Error: #{e.message}"
end

Convenience for loading config/foo.yml for the current Rails env.

Example:

# config/exception_notification.yml:
production:
  url: http://127.0.0.1:8080
  namespace: my_app_production
development:
  url: http://localhost:3001
  namespace: my_app_development

# config/production.rb
Rails.application.configure do
  config.middleware.use ExceptionNotifier, config_for(:exception_notification)
end
console(&blk) Show source
# File railties/lib/rails/application.rb, line 289
def console(&blk)
  self.class.console(&blk)
end

Sends any console called in the instance of a new application up to the console method defined in Rails::Railtie.

env_config() Show source
# File railties/lib/rails/application.rb, line 244
def env_config
  @app_env_config ||= begin
    validate_secret_key_config!

    super.merge({
      "action_dispatch.parameter_filter" => config.filter_parameters,
      "action_dispatch.redirect_filter" => config.filter_redirect,
      "action_dispatch.secret_token" => secrets.secret_token,
      "action_dispatch.secret_key_base" => secrets.secret_key_base,
      "action_dispatch.show_exceptions" => config.action_dispatch.show_exceptions,
      "action_dispatch.show_detailed_exceptions" => config.consider_all_requests_local,
      "action_dispatch.logger" => Rails.logger,
      "action_dispatch.backtrace_cleaner" => Rails.backtrace_cleaner,
      "action_dispatch.key_generator" => key_generator,
      "action_dispatch.http_auth_salt" => config.action_dispatch.http_auth_salt,
      "action_dispatch.signed_cookie_salt" => config.action_dispatch.signed_cookie_salt,
      "action_dispatch.encrypted_cookie_salt" => config.action_dispatch.encrypted_cookie_salt,
      "action_dispatch.encrypted_signed_cookie_salt" => config.action_dispatch.encrypted_signed_cookie_salt,
      "action_dispatch.cookies_serializer" => config.action_dispatch.cookies_serializer,
      "action_dispatch.cookies_digest" => config.action_dispatch.cookies_digest
    })
  end
end

Stores some of the Rails initial environment parameters which will be used by middlewares and engines to configure themselves.

Calls superclass method
generators(&blk) Show source
# File railties/lib/rails/application.rb, line 295
def generators(&blk)
  self.class.generators(&blk)
end

Sends any generators called in the instance of a new application up to the generators method defined in Rails::Railtie.

initialized?() Show source
# File railties/lib/rails/application.rb, line 142
def initialized?
  @initialized
end

Returns true if the application is initialized.

initializer(name, opts={}, &block) Show source
# File railties/lib/rails/application.rb, line 277
def initializer(name, opts={}, &block)
  self.class.initializer(name, opts, &block)
end

Sends the initializers to the initializer method defined in the Rails::Initializable module. Each Rails::Application class has its own set of initializers, as defined by the Initializable module.

isolate_namespace(mod) Show source
# File railties/lib/rails/application.rb, line 300
def isolate_namespace(mod)
  self.class.isolate_namespace(mod)
end

Sends the isolate_namespace method up to the class method.

key_generator() Show source
# File railties/lib/rails/application.rb, line 174
def key_generator
  # number of iterations selected based on consultation with the google security
  # team. Details at https://github.com/rails/rails/pull/6952#issuecomment-7661220
  @caching_key_generator ||=
    if secrets.secret_key_base
      key_generator = ActiveSupport::KeyGenerator.new(secrets.secret_key_base, iterations: 1000)
      ActiveSupport::CachingKeyGenerator.new(key_generator)
    else
      ActiveSupport::LegacyKeyGenerator.new(secrets.secret_token)
    end
end

Return the application's KeyGenerator

message_verifier(verifier_name) Show source
# File railties/lib/rails/application.rb, line 204
def message_verifier(verifier_name)
  @message_verifiers[verifier_name] ||= begin
    secret = key_generator.generate_key(verifier_name.to_s)
    ActiveSupport::MessageVerifier.new(secret)
  end
end

Returns a message verifier object.

This verifier can be used to generate and verify signed messages in the application.

It is recommended not to use the same verifier for different things, so you can get different verifiers passing the verifier_name argument.

Parameters

  • verifier_name - the name of the message verifier.

Examples

message = Rails.application.message_verifier('sensitive_data').generate('my sensible data')
Rails.application.message_verifier('sensitive_data').verify(message)
# => 'my sensible data'

See the ActiveSupport::MessageVerifier documentation for more information.

rake_tasks(&block) Show source
# File railties/lib/rails/application.rb, line 270
def rake_tasks(&block)
  self.class.rake_tasks(&block)
end

If you try to define a set of rake tasks on the instance, these will get passed up to the rake tasks defined on the application's class.

reload_routes!() Show source
# File railties/lib/rails/application.rb, line 169
def reload_routes!
  routes_reloader.reload!
end

Reload application routes regardless if they changed or not.

runner(&blk) Show source
# File railties/lib/rails/application.rb, line 283
def runner(&blk)
  self.class.runner(&blk)
end

Sends any runner called in the instance of a new application up to the runner method defined in Rails::Railtie.

secrets() Show source
# File railties/lib/rails/application.rb, line 385
def secrets
  @secrets ||= begin
    secrets = ActiveSupport::OrderedOptions.new
    yaml = config.paths["config/secrets"].first
    if File.exist?(yaml)
      require "erb"
      all_secrets = YAML.load(ERB.new(IO.read(yaml)).result) || {}
      env_secrets = all_secrets[Rails.env]
      secrets.merge!(env_secrets.symbolize_keys) if env_secrets
    end

    # Fallback to config.secret_key_base if secrets.secret_key_base isn't set
    secrets.secret_key_base ||= config.secret_key_base
    # Fallback to config.secret_token if secrets.secret_token isn't set
    secrets.secret_token ||= config.secret_token

    secrets
  end
end

Returns secrets added to config/secrets.yml.

Example:

development:
  secret_key_base: 836fa3665997a860728bcb9e9a1e704d427cfc920e79d847d79c8a9a907b9e965defa4154b2b86bdec6930adbe33f21364523a6f6ce363865724549fdfc08553
test:
  secret_key_base: 5a37811464e7d378488b0f073e2193b093682e4e21f5d6f3ae0a4e1781e61a351fdc878a843424e81c73fb484a40d23f92c8dafac4870e74ede6e5e174423010
production:
  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>
  namespace: my_app_production

Rails.application.secrets.namespace returns my_app_production in the production environment.

© 2004–2018 David Heinemeier Hansson
Licensed under the MIT License.