Configuration

Environments in Rails

Database Configuration

Database configuration of a rails project lies in a file config/database.yml. If you create a project using rails new command and don’t specify a database engine to be used then rails uses sqlite as the default database. A typical database.yml file with default configuration will look similar to following.

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
#
default: &default
  adapter: sqlite3
  pool: 5
  timeout: 5000

development:
  <<: *default
  database: db/development.sqlite3

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: db/test.sqlite3

production:
  <<: *default
  database: db/production.sqlite3

If you want to change the default database while creating a new project you can specify database: rails new hello_world --database=mysql

Rails General Configuration

The following configuration options should be called on a Rails::Railtie object

• config.after_initialize: Takes a block which will be run after rails has initialized the application.
• config.asset_host: This sets the host for the assets. This is useful when using a Content Delivery Network. This is shorthand for config.action_controller.asset_host
• config.autoload_once_paths: This option accepts an array of paths where Rails autoloads constants. The default value is an empty array
• config.autoload_paths: This accepts an array of paths where Rails autoloads constants. It defaults to all directories under app
• config.cache_classes: Determines if classes and modules should be reloaded on each request. In development mode, this defaults to false and in the production and test modes it defaults to true
• config.action_view.cache_template_loading: This determines if templates should be reloaded on each request. It defaults to the config.cache_classes setting
• config.beginning_of_week: This sets the default beginning of week. It requires a valid week day symbol (:monday)
• config.cache_store: Choose which cache store to use. Options include :file_store, :memory_store, mem_cache_store or null_store.
• config.colorize_logging: This controls whether logging information is colorized
• config.eager_load: Eager-loads all registered
• config.encoding: Specifies the application encoding. The default value is UTF-8
• config.log_level: Sets the verbosity of the Rails Logger. It defaults to :debug in all environments.
• config.middleware: Use this to configure the application’s middleware
• config.time_zone: This sets the application’s default time zone.

Configuring assets

The following configuration options can be used for configuring assets

• config.assets.enabled: Determines whether the asset pipeline is enabled. This defaults to true
• config.assets.raise_runtime_errors: This enables runtime error checking. It’s useful for development mode
• config.assets.compress: Lets assets be compressed. In production mode, this defaults to true
• config.assets.js_compressor: Specifies which JS compressor to use. Options include :closure, :uglifier and :yui
• config.assets.paths: Specifies which paths to search for assets.
• config.assets.precompile: Lets you choose additional assets to be precompiled when rake assets:precompile is run
• config.assets.digest: This option allows the use of MD-5 fingerprints in the asset names. It defaults to true in development mode
• config.assets.compile: Toggles live Sprockets compilation in production mode

Configuring generators

Rails allows you to configure what generators are used when running rails generate commands. This method, config.generators takes a block

config.generators do |g|
  g.orm :active_record
  g.test_framework :test_unit
end

Here are some of the options