class Rails::Application
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.
Attributes
Public Class Methods
# File railties/lib/rails/application.rb, line 102
def create(initial_variable_values = {}, &block)
new(initial_variable_values, &block).run_load_hooks!
end # File railties/lib/rails/application.rb, line 106 def find_root(from) find_root_with_flag "config.ru", from, Dir.pwd end
# File railties/lib/rails/application.rb, line 91 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
# File railties/lib/rails/application.rb, line 98 def instance super.run_load_hooks! end
# File railties/lib/rails/application.rb, line 127
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 Public Instance Methods
# File railties/lib/rails/application.rb, line 226
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 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 298 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.
# File railties/lib/rails/application.rb, line 441
def credentials
@credentials ||= encrypted("config/credentials.yml.enc")
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.
# File railties/lib/rails/application.rb, line 472
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 bin/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")
# File railties/lib/rails/application.rb, line 247
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_token" => secrets.secret_token,
"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.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
)
end
end 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 304 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.
# File railties/lib/rails/application.rb, line 148 def initialized? @initialized end
Returns true if the application is initialized.
# File railties/lib/rails/application.rb, line 286
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.
# File railties/lib/rails/application.rb, line 309 def isolate_namespace(mod) self.class.isolate_namespace(mod) end
Sends the isolate_namespace method up to the class method.
# File railties/lib/rails/application.rb, line 172
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 secret_key_base
ActiveSupport::CachingKeyGenerator.new(
ActiveSupport::KeyGenerator.new(secret_key_base, iterations: 1000)
)
else
ActiveSupport::LegacyKeyGenerator.new(secrets.secret_token)
end
end Returns the application's KeyGenerator
# File railties/lib/rails/application.rb, line 203
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.
# File railties/lib/rails/application.rb, line 279 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.
# File railties/lib/rails/application.rb, line 167 def reload_routes! routes_reloader.reload! end
Reload application routes regardless if they changed or not.
# File railties/lib/rails/application.rb, line 292 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.
# File railties/lib/rails/application.rb, line 428
def secret_key_base
if Rails.env.test? || Rails.env.development?
secrets.secret_key_base || Digest::MD5.hexdigest(self.class.name)
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 test and development, this is simply derived as a MD5 hash of the application's name.
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.
# File railties/lib/rails/application.rb, line 394
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
if secrets.secret_token.present?
ActiveSupport::Deprecation.warn(
"`secrets.secret_token` is deprecated in favor of `secret_key_base` and will be removed in Rails 6.0."
)
end
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.
Protected Instance Methods
# File railties/lib/rails/application.rb, line 579
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`"
elsif secrets.secret_token.blank?
raise ArgumentError, "Missing `secret_key_base` for '#{Rails.env}' environment, set this string with `rails credentials:edit`"
end
end
© 2004–2018 David Heinemeier Hansson
Licensed under the MIT License.