Class: Rails::Application

Inherits:
Engine show all
Defined in:
railties/lib/rails/application.rb,
railties/lib/rails/application/finisher.rb,
railties/lib/rails/application/bootstrap.rb,
railties/lib/rails/application/configuration.rb,
railties/lib/rails/application/routes_reloader.rb,
railties/lib/rails/application/default_middleware_stack.rb

Overview

An Engine 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 set up 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 them manually.

Defined Under Namespace

Modules: Bootstrap, Finisher Classes: Configuration, DefaultMiddlewareStack, RoutesReloader

Constant Summary collapse

INITIAL_VARIABLES =
[:config, :railties, :routes_reloader, :reloaders,
:routes, :helpers, :app_env_config, :secrets]

Constants inherited from Railtie

Railtie::ABSTRACT_RAILTIES

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Engine

#app, #call, #endpoint, endpoint, find, #helpers, isolate_namespace, #load_console, #load_generators, #load_runner, #load_seed, #load_tasks, #railties, #routes, #routes?

Methods inherited from Railtie

abstract_railtie?, #configure, configure, console, generators, railtie_name, #railtie_namespace, rake_tasks, runner, subclasses

Methods included from Initializable

included, #run_initializers

Constructor Details

#initialize(initial_variable_values = {}, &block) ⇒ Application

Returns a new instance of Application.


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# File 'railties/lib/rails/application.rb', line 129

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

  @executor          = Class.new(ActiveSupport::Executor)
  @reloader          = Class.new(ActiveSupport::Reloader)
  @reloader.executor = @executor

  # are these actually used?
  @initial_variable_values = initial_variable_values
  @block = block
end

Instance Attribute Details

#assetsObject

Returns the value of attribute assets


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# File 'railties/lib/rails/application.rb', line 120

def assets
  @assets
end

#configObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 390

def config #:nodoc:
  @config ||= Application::Configuration.new(self.class.find_root(self.class.called_from))
end

#executorObject (readonly)

Returns the value of attribute executor


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# File 'railties/lib/rails/application.rb', line 122

def executor
  @executor
end

#reloaderObject (readonly)

Returns the value of attribute reloader


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# File 'railties/lib/rails/application.rb', line 122

def reloader
  @reloader
end

#reloadersObject (readonly)

Returns the value of attribute reloaders


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# File 'railties/lib/rails/application.rb', line 122

def reloaders
  @reloaders
end

#sandboxObject Also known as: sandbox?

Returns the value of attribute sandbox


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# File 'railties/lib/rails/application.rb', line 120

def sandbox
  @sandbox
end

#secretsObject

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.


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# File 'railties/lib/rails/application.rb', line 410

def secrets
  @secrets ||= begin
    secrets = ActiveSupport::OrderedOptions.new
    files = config.paths["config/secrets"].existent
    files = files.reject { |path| path.end_with?(".enc") } unless config.read_encrypted_secrets
    secrets.merge! Rails::Secrets.parse(files, env: Rails.env)

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

    secrets
  end
end

Class Method Details

.add_lib_to_load_path!(root) ⇒ Object

This method is called just after an application inherits from Rails::Application, allowing the developer to load classes in lib and use them during application configuration.

class MyApplication < Rails::Application
  require "my_backend" # in lib/my_backend
  config.i18n.backend = MyBackend
end

Notice this method takes into consideration the default root path. So if you are changing config.root inside your application definition or having a custom Rails application, you will need to add lib to $LOAD_PATH on your own in case you need to load files in lib/ during the application configuration as well.


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# File 'railties/lib/rails/application.rb', line 346

def self.add_lib_to_load_path!(root) #:nodoc:
  path = File.join root, "lib"
  if File.exist?(path) && !$LOAD_PATH.include?(path)
    $LOAD_PATH.unshift(path)
  end
end

.create(initial_variable_values = {}, &block) ⇒ Object


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# File 'railties/lib/rails/application.rb', line 104

def create(initial_variable_values = {}, &block)
  new(initial_variable_values, &block).run_load_hooks!
end

.find_root(from) ⇒ Object


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# File 'railties/lib/rails/application.rb', line 108

def find_root(from)
  find_root_with_flag "config.ru", from, Dir.pwd
end

.inherited(base) ⇒ Object


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# File 'railties/lib/rails/application.rb', line 93

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

.instanceObject


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# File 'railties/lib/rails/application.rb', line 100

def instance
  super.run_load_hooks!
end

Instance Method Details

#config_for(name, env: Rails.env) ⇒ Object

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

Examples:

# 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/environments/production.rb
Rails.application.configure do
  config.middleware.use ExceptionNotifier, config_for(:exception_notification)
end

# You can also store configurations in a shared section which will be
# merged with the environment configuration

# config/example.yml
shared:
  foo:
    bar:
      baz: 1

development:
  foo:
    bar:
      qux: 2

# development environment
Rails.application.config_for(:example)[:foo][:bar]
# => { baz: 1, qux: 2 }

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# File 'railties/lib/rails/application.rb', line 242

def config_for(name, env: Rails.env)
  yaml = name.is_a?(Pathname) ? name : Pathname.new("#{paths["config"].existent.first}/#{name}.yml")

  if yaml.exist?
    require "erb"
    all_configs    = ActiveSupport::ConfigurationFile.parse(yaml, symbolize_names: true)
    config, shared = all_configs[env.to_sym], all_configs[:shared]

    if config.is_a?(Hash)
      ActiveSupport::OrderedOptions.new.update(shared&.deep_merge(config) || config)
    else
      config || shared
    end
  else
    raise "Could not load configuration. No such file - #{yaml}"
  end
end

#console(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 316

def console(&blk)
  self.class.console(&blk)
end

#credentialsObject

Decrypts the credentials hash as kept in config/credentials.yml.enc. This file is encrypted with the Rails master key, which is either taken from ENV["RAILS_MASTER_KEY"] or from loading config/master.key. If specific credentials file exists for current environment, it takes precedence, thus for production environment look first for config/credentials/production.yml.enc with master key taken from ENV["RAILS_MASTER_KEY"] or from loading config/credentials/production.key. Default behavior can be overwritten by setting config.credentials.content_path and config.credentials.key_path.


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# File 'railties/lib/rails/application.rb', line 452

def credentials
  @credentials ||= encrypted(config.credentials.content_path, key_path: config.credentials.key_path)
end

#eager_load!Object

Eager loads the application code.


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# File 'railties/lib/rails/application.rb', line 517

def eager_load!
  if Rails.autoloaders.zeitwerk_enabled?
    Rails.autoloaders.each(&:eager_load)
  else
    super
  end
end

#encrypted(path, key_path: "config/master.key", env_key: "RAILS_MASTER_KEY") ⇒ Object

Shorthand to decrypt any encrypted configurations or files.

For any file added with rails encrypted:edit call read to decrypt the file with the master key. The master key is either stored in config/master.key or ENV["RAILS_MASTER_KEY"].

Rails.application.encrypted("config/mystery_man.txt.enc").read
# => "We've met before, haven't we?"

It's also possible to interpret encrypted YAML files with config.

Rails.application.encrypted("config/credentials.yml.enc").config
# => { next_guys_line: "I don't think so. Where was it you think we met?" }

Any top-level configs are also accessible directly on the return value:

Rails.application.encrypted("config/credentials.yml.enc").next_guys_line
# => "I don't think so. Where was it you think we met?"

The files or configs can also be encrypted with a custom key. To decrypt with a key in the ENV, use:

Rails.application.encrypted("config/special_tokens.yml.enc", env_key: "SPECIAL_TOKENS")

Or to decrypt with a file, that should be version control ignored, relative to Rails.root:

Rails.application.encrypted("config/special_tokens.yml.enc", key_path: "config/special_tokens.key")

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# File 'railties/lib/rails/application.rb', line 483

def encrypted(path, key_path: "config/master.key", env_key: "RAILS_MASTER_KEY")
  ActiveSupport::EncryptedConfiguration.new(
    config_path: Rails.root.join(path),
    key_path: Rails.root.join(key_path),
    env_key: env_key,
    raise_if_missing_key: config.require_master_key
  )
end

#env_configObject

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


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# File 'railties/lib/rails/application.rb', line 262

def env_config
  @app_env_config ||= begin
    super.merge(
      "action_dispatch.parameter_filter" => config.filter_parameters,
      "action_dispatch.redirect_filter" => config.filter_redirect,
      "action_dispatch.secret_key_base" => 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.authenticated_encrypted_cookie_salt" => config.action_dispatch.authenticated_encrypted_cookie_salt,
      "action_dispatch.use_authenticated_cookie_encryption" => config.action_dispatch.use_authenticated_cookie_encryption,
      "action_dispatch.encrypted_cookie_cipher" => config.action_dispatch.encrypted_cookie_cipher,
      "action_dispatch.signed_cookie_digest" => config.action_dispatch.signed_cookie_digest,
      "action_dispatch.cookies_serializer" => config.action_dispatch.cookies_serializer,
      "action_dispatch.cookies_digest" => config.action_dispatch.cookies_digest,
      "action_dispatch.cookies_rotations" => config.action_dispatch.cookies_rotations,
      "action_dispatch.cookies_same_site_protection" => coerce_same_site_protection(config.action_dispatch.cookies_same_site_protection),
      "action_dispatch.use_cookies_with_metadata" => config.action_dispatch.,
      "action_dispatch.content_security_policy" => config.content_security_policy,
      "action_dispatch.content_security_policy_report_only" => config.content_security_policy_report_only,
      "action_dispatch.content_security_policy_nonce_generator" => config.content_security_policy_nonce_generator,
      "action_dispatch.content_security_policy_nonce_directives" => config.content_security_policy_nonce_directives,
      "action_dispatch.feature_policy" => config.feature_policy,
    )
  end
end

#generators(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 322

def generators(&blk)
  self.class.generators(&blk)
end

#helpers_pathsObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 496

def helpers_paths #:nodoc:
  config.helpers_paths
end

#initialize!(group = :default) ⇒ Object

Initialize the application passing the given group. By default, the group is :default


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# File 'railties/lib/rails/application.rb', line 377

def initialize!(group = :default) #:nodoc:
  raise "Application has been already initialized." if @initialized
  run_initializers(group, self)
  @initialized = true
  self
end

#initialized?Boolean

Returns true if the application is initialized.

Returns:

  • (Boolean)

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# File 'railties/lib/rails/application.rb', line 150

def initialized?
  @initialized
end

#initializer(name, opts = {}, &block) ⇒ Object

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.


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# File 'railties/lib/rails/application.rb', line 304

def initializer(name, opts = {}, &block)
  self.class.initializer(name, opts, &block)
end

#initializersObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 384

def initializers #:nodoc:
  Bootstrap.initializers_for(self) +
  railties_initializers(super) +
  Finisher.initializers_for(self)
end

#isolate_namespace(mod) ⇒ Object

Sends the isolate_namespace method up to the class method.


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# File 'railties/lib/rails/application.rb', line 327

def isolate_namespace(mod)
  self.class.isolate_namespace(mod)
end

#key_generatorObject

Returns the application's KeyGenerator


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# 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 ||= ActiveSupport::CachingKeyGenerator.new(
    ActiveSupport::KeyGenerator.new(secret_key_base, iterations: 1000)
  )
end

#message_verifier(verifier_name) ⇒ Object

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.


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# File 'railties/lib/rails/application.rb', line 200

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

#migration_railtiesObject

Return an array of railties respecting the order they're loaded and the order specified by the railties_order config.

While running initializers we need engines in reverse order here when copying migrations from railties ; we need them in the order given by railties_order.


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# File 'railties/lib/rails/application.rb', line 512

def migration_railties # :nodoc:
  ordered_railties.flatten - [self]
end

#rake_tasks(&block) ⇒ Object

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.


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# File 'railties/lib/rails/application.rb', line 297

def rake_tasks(&block)
  self.class.rake_tasks(&block)
end

#reload_routes!Object

Reload application routes regardless if they changed or not.


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# File 'railties/lib/rails/application.rb', line 169

def reload_routes!
  routes_reloader.reload!
end

#require_environment!Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 353

def require_environment! #:nodoc:
  environment = paths["config/environment"].existent.first
  require environment if environment
end

#routes_reloaderObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 358

def routes_reloader #:nodoc:
  @routes_reloader ||= RoutesReloader.new
end

#run_load_hooks!Object

:nodoc:


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# File 'railties/lib/rails/application.rb', line 154

def run_load_hooks! # :nodoc:
  return self if @ran_load_hooks
  @ran_load_hooks = true

  @initial_variable_values.each do |variable_name, value|
    if INITIAL_VARIABLES.include?(variable_name)
      instance_variable_set("@#{variable_name}", value)
    end
  end

  instance_eval(&@block) if @block
  self
end

#runner(&blk) ⇒ Object

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


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# File 'railties/lib/rails/application.rb', line 310

def runner(&blk)
  self.class.runner(&blk)
end

#secret_key_baseObject

The secret_key_base is used as the input secret to the application's key generator, which in turn is used to create all MessageVerifiers/MessageEncryptors, including the ones that sign and encrypt cookies.

In development and test, this is randomly generated and stored in a temporary file in tmp/development_secret.txt.

In all other environments, we look for it first in ENV, then credentials.secret_key_base, and finally secrets.secret_key_base. For most applications, the correct place to store it is in the encrypted credentials file.


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# File 'railties/lib/rails/application.rb', line 435

def secret_key_base
  if Rails.env.development? || Rails.env.test?
    secrets.secret_key_base ||= generate_development_secret
  else
    validate_secret_key_base(
      ENV["SECRET_KEY_BASE"] || credentials.secret_key_base || secrets.secret_key_base
    )
  end
end

#to_appObject

:nodoc:


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# File 'railties/lib/rails/application.rb', line 492

def to_app #:nodoc:
  self
end

#watchable_argsObject

Returns an array of file paths appended with a hash of directories-extensions suitable for ActiveSupport::FileUpdateChecker API.


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# File 'railties/lib/rails/application.rb', line 365

def watchable_args #:nodoc:
  files, dirs = config.watchable_files.dup, config.watchable_dirs.dup

  ActiveSupport::Dependencies.autoload_paths.each do |path|
    File.file?(path) ? files << path.to_s : dirs[path.to_s] = [:rb]
  end

  [files, dirs]
end