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 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
them manually.
- MODULE Rails::Application::Bootstrap
- MODULE Rails::Application::Finisher
- CLASS Rails::Application::Configuration
- CLASS Rails::Application::DefaultMiddlewareStack
- CLASS Rails::Application::RoutesReloader
- C
- E
- F
- G
- I
- K
- M
- N
- R
- S
INITIAL_VARIABLES | = | [:config, :railties, :routes_reloader, :reloaders, :routes, :helpers, :app_env_config, :secrets] |
[RW] | assets | |
[R] | executor | |
[R] | reloader | |
[R] | reloaders | |
[RW] | sandbox | |
[RW] | sandbox? |
# File railties/lib/rails/application.rb, line 123 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
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/environments/production.rb
Rails.application.configure do
config.middleware.use ExceptionNotifier, config_for(:exception_notification)
end
# File railties/lib/rails/application.rb, line 224 def config_for(name, env: Rails.env) if name.is_a?(Pathname) yaml = name else yaml = Pathname.new("#{paths["config"].existent.first}/#{name}.yml") end if yaml.exist? require "erb" (YAML.load(ERB.new(yaml.read).result) || {})[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
Sends any console called in the instance of a new application up to the
console
method defined in Rails::Railtie.
Stores some of the Rails initial environment parameters which will be used by middlewares and engines to configure themselves.
# File railties/lib/rails/application.rb, line 245 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
Sends any generators called in the instance of a new application up to the
generators
method defined in Rails::Railtie.
Returns true if the application is initialized.
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.
Sends the isolate_namespace
method up to the class method.
Returns the application's KeyGenerator
# File railties/lib/rails/application.rb, line 168 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 unless secrets.secret_key_base.kind_of?(String) raise ArgumentError, "`secret_key_base` for #{Rails.env} environment must be a type of String, change this value in `config/secrets.yml`" end 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
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.
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 application routes regardless if they changed or not.
Sends any runner called in the instance of a new application up to the
runner
method defined in Rails::Railtie.
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.
# File railties/lib/rails/application.rb, line 386 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 # Fallback to config.secret_token if secrets.secret_token isn't set secrets.secret_token ||= config.secret_token secrets end end