class Rails::Application

Parent:: Engine

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.

Attributes

assets[RW]

config[W]

credentials[W]

executor[R]

reloader[R]

reloaders[R]

sandbox[RW]

sandbox?[RW]

secrets[W]

Public Class Methods

create(initial_variable_values = {}, &block) Show source

# File railties/lib/rails/application.rb, line 103
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 107
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 92
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 99
def instance
  super.run_load_hooks!
end

Calls superclass method

new(initial_variable_values = {}, &block) Show source

# File railties/lib/rails/application.rb, line 128
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

Calls superclass method

Public Instance Methods

config_for(name, env: Rails.env) Show source

# File railties/lib/rails/application.rb, line 241
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).deep_symbolize_keys
    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

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 }

console(&blk) Show source

# File railties/lib/rails/application.rb, line 315
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.

credentials() Show source

# File railties/lib/rails/application.rb, line 443
def credentials
  @credentials ||= encrypted(config.credentials.content_path, key_path: config.credentials.key_path)
end

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.

eager_load!() Show source

# File railties/lib/rails/application.rb, line 508
def eager_load!
  if Rails.autoloaders.zeitwerk_enabled?
    Rails.autoloaders.each(&:eager_load)
  else
    super
  end
end

Eager loads the application code.

Calls superclass method

encrypted(path, key_path: "config/master.key", env_key: "RAILS_MASTER_KEY") Show source

# File railties/lib/rails/application.rb, line 474
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

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")

env_config() Show source

# File railties/lib/rails/application.rb, line 261
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.use_cookies_with_metadata,
      "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.permissions_policy" => config.permissions_policy,
    )
  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 321
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 149
def initialized?
  @initialized
end

Returns true if the application is initialized.

initializer(name, opts = {}, &block) Show source

# File railties/lib/rails/application.rb, line 303
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 332
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 173
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

Returns the application's KeyGenerator

message_verifier(verifier_name) Show source

# File railties/lib/rails/application.rb, line 199
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 296
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 168
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 309
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.

secret_key_base() Show source

# File railties/lib/rails/application.rb, line 426
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

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.

secrets() Show source

# File railties/lib/rails/application.rb, line 401
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

server(&blk) Show source

# File railties/lib/rails/application.rb, line 327
def server(&blk)
  self.class.server(&blk)
end

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

Protected Instance Methods

validate_secret_key_base(secret_key_base) Show source

# File railties/lib/rails/application.rb, line 590
def validate_secret_key_base(secret_key_base)
  if secret_key_base.is_a?(String) && secret_key_base.present?
    secret_key_base
  elsif secret_key_base
    raise ArgumentError, "`secret_key_base` for #{Rails.env} environment must be a type of String`"
  else
    raise ArgumentError, "Missing `secret_key_base` for '#{Rails.env}' environment, set this string with `bin/rails credentials:edit`"
  end
end

Docs

Docs4dev

Title here

class Rails::Application

Initialization

`Configuration`

Routes

Middlewares

Booting process

Multiple Applications

Attributes

Public Class Methods

Public Instance Methods

Parameters

Examples

Protected Instance Methods