Rails guidelines

Don't add Ruby version to Gemfile because it's impossible to say, e.g. use Ruby 2.1 or any higher version. Instead, put preferred ruby version in README.md file.

In case you use heroku-build-pack ruby version in Gemfile is required. You can use ENV to temporarily use another version:
```
# Gemfile
source "https://rubygems.org"
gem "bundler", ">= 1.7.0"

ruby ENV["GEMFILE_RUBY"] || "2.2.2"

# shell
$ export GEMFILE_RUBY=2.1.2; rails s
```
Use service objects for decomposing application Try not to use for example observers or filters.
Group gems in meaningful groups (not alphabetically).
When using an unofficial version of a gem (from a fork or different branch/revision) always include a short comment explaining the reasons. The idea is to know when the declaration can be switched back to using official version. E.g.
```
# We need feature X that is available only in this branch
gem 'activeadmin', github: 'gregbell/active_admin', branch: 'master'
```
Use CoffeeScript instead of plain JavaScript.
When making time-based statistic use the midnight of next day as upper limit.

Split upload path into subdirectories.

# partition_uid("1234567890")
# => "123/456/789/0"
def partition_uid(uid, size)
    uid.gsub(/(.{#{size}})/, "\\1/")
end

If converting images, optimize them for web. imagemagick options: -strip +profile "exif" -quality 80.

If using whenever, set absolute paths.

set :output, File.join("log", "cron.log")
job_type :rake, "cd :path && RAILS_ENV=:environment /usr/local/bin/bundle exec rake :task :output"

In non-SPA applications render URLs for JavaScript on server side. If you need to add them to custom JavaScript component, just print the links and iterate through them:
```
$('a').each (index, el) -> carousel.add(index, el)
```
Use I18n kes instead of plain text in views. In order to keep the reusability, the translation strings shouldn’t contain punctuation at their end, because those belong to the very UI.
Use attr_accessible instead of attr_protected.
Occasionally run rails_best_practices command, and follow the hints.
For more advanced apps, setup vagrant along with puppet provisioner. The puppet file shoud be kept in manifests/site.pp.
If using strong_parameters gem, turn whitelist_attributes off, otherwise leave it enabled.
Use unicorn server in production.
Secure secure token in public projects.

Put it in settings.yml on production and generate once during initial setup, change when needed.
Use rails-timeago gem by default. Don't render "ago" dates on server-side.

The reason is they need to be often updated in real-time on browser side. For example 3 minutes after staying on page "1 minute ago" should say "4 minutes ago".
Use bin/setup file as thoughtbot describes (for example for git hooks).
Never ever ever use natural keys in your database.
Do not add files to vendor/assets. Find proper gem or create a new one in rails-assets.
Use InnoDB database format instead of MyISAM
Use lograge to improve Rails default logging format.
If you want your model to be compatible with ActiveModel, include ActiveModel::Model in Rails 4, and include ActiveAttr::Model in Rails 3. If not, use Virtus instead
Add db/schema.rb to .gitignore
Use single file extension for default cases. Instead of file.html.slim, file.css.sass, file.js.coffee use file.slim, file.sass, file.coffee
Use \A and \z to validate user input instead of ^ and $

username = "<script>alert(1)</script>\nsheerun"
!!username.match(/^[a-z]+$/)   # => true
!!username.match(/\A[a-z]+\z/) # => false

How to choose database

If you think about using mysql - use postgresql
If you think about using mongodb - think again, spend more time thinking if you really need mongodb features, if not - use postgres

Setup generators

# config/application.rb
config.generators do |g|
  g.helper      false
  g.stylesheets false
  g.javascripts false
  g.view_specs  false
end

Remember to add indexes for foreign keys

class CreateComments < ActiveRecord::Migration
  def change
    create_table :comments do |t|
      t.integer :post_id
      t.integer :user_id

      # ...
    end

    add_index :comments, :post_id # <= this
    add_index :comments, :user_id # <= and this
  end
end

Suggested gems for Rails applications

gem 'yajl-ruby', require: 'yajl'
gem 'strong_parameters'
gem 'slim-rails'
gem 'sidekiq'
gem 'devise-async'
gem 'decent_exposure'
gem 'schema_plus'
gem 'coffee-rails-source-maps'
gem 'no_more_pending_migrations'

group :test do
  gem 'rspec-rails'
  # gem 'rspec-fire' # anytime you use mocks or stubs
end

group :assets do
  gem 'rails-timeago', '~> 2.0'
end

group :development do
  gem 'letter_opener'
  gem 'rails_best_practices'
  gem 'commands'
end

Setup proper redis namespaces

Rails cache store

# config/application.rb
config.cache_store = :redis_store, "redis://localhost:6379/0/app_name:#{Rails.env}:cache"

Rails session store

# config/initializers/session_store.rb
Rails.application.config.session_store :redis_store, :redis_server => { :namespace => "app_name:#{Rails.env}:session" }

Rack cache

# config/environments/production.rb
config.action_dispatch.rack_cache = {
  :metastore    => "redis://localhost:6379/0/app_name:#{Rails.env}:rack-cache:metastore",
  :entitystore  => "redis://localhost:6379/0/app_name:#{Rails.env}:rack-cache:entitystore"
}

Sidekiq

# config/initializers/sidekiq.rb
Sidekiq.configure_server do |config|
  config.redis = { :namespace => "app_name:#{Rails.env}:sidekiq" }
end

Sidekiq.configure_client do |config|
  config.redis = { :namespace => "app_name:#{Rails.env}:sidekiq" }
end

Faye server

# faye.ru
faye_server = Faye::RackAdapter.new(
  :mount => '/faye',
  :timeout => 30,
  :engine => {
    :type  => Faye::Redis, # or Faye::PersistentRedis
    :namespace => "app_name:#{ENV["RACK_ENV"]}:faye:"
  }
)

Source maps

# Do not compress assets
config.assets.compress = false

# Expands the lines which load the assets
config.assets.debug = true

# Enable sources maps
config.sass.debug_info = true
config.sass.line_comments = false

Redis

Use raw: true option when using redis as a cache store.

Example:

class MyController
  def index
    render_cached_json("api:foos", expires_in: 1.hour) do
      Foo.all
    end
  end

  def render_cached_json(cache_key, opts = {}, &block)
    opts[:expires_in] ||= 1.day

    expires_in opts[:expires_in], :public => true
    data = Rails.cache.fetch(cache_key, {raw: true}.merge(opts)) do
      block.call.to_json
    end

    render :json => data
  end
end

This will store rendered json in redis, plain json, as string, as you should it should always do. Notice where is to_json and raw: true option. And you get HTTP cache headers for free.

According to issue in redis-rails - which don't set expire time properly https://github.com/redis-store/redis-rails/issues/10

Please use https://github.com/roidrage/redis-session-store for storing rails session in redis.

Mongodb

Remember to include

gem "bson_ext"

when using mongodb (you know, for speed)

Add environment tag in Raven config

Raven.configure do |config|
  config.dsn = 'https://some-dsn-here'
  config.tags = { environment: Rails.env }
end

Configuration files

Add sample configuration.yml file to repository and write about it in README. The file should be named using the following convention:

FILE_NAME.EXT -> FILE_NAME.sample.EXT, so database.yml becomes database.sample.yml. This is better than FILE_NAME.EXT.example because it keeps the file extension in place.

Files that should have samples:

config/database.yml - obvious
config/mongoid.yml - if using mongo...
config/application.yml - for lovely cat
config/settings.*.yml, config/settings/*.yml madness - rails_config you bustard

Remember to set reserved subdomains

RESERVED_SUBDOMAINS = %w(
  about abuse account accounts admin admins administrator
  administrators anonymous api assets billing billings board calendar
  contact copyright e-mail email example feedback forum
  hostmaster image images inbox index invite jabber legal
  launchpad manage media messages mobile official payment
  picture pictures policy portal postmaster press privacy
  private profile search sitemap staff stage staging static
  stats status support teams username usernames users webmail
  webmaster login use jars main data user img css stylesheets
  cdn gallery info system www
)

validates :domain, presence: true,
                   subdomain: { reserved: RESERVED_SUBDOMAINS }

Devise

Avoid switching from DELETE to GET for signout. It should be considered as a potential security hole.

If using gem from github put it under monterail organization

gem "ssl_routes", :github => "monterail/ssl_routes"

instead of

gem "ssl_routes", :github => "sheerun/ssl_routes"

Bus factor++

Disable Rack::Cache for rails < 4

For apps running rails version < 4 set

config.action_controller.perform_caching = true

Rails will automagicly add Rack::Cache middleware to the top of stack. This will cause request with cache headers to be cached which can break e.g. authentication when you want to send cache headers but also always require http basic auth. It is also much better to use nginx or varnish as cache in case auth is not an issue. See this pull request for reference.

localeapp pull policy

When using localeapp pull always do that on the same branch (preferebly master).
Do not commit translation files in feature branches. If you do you gonna have a baaaad time when merging it to master.

roar

Prevent weird bugs when using roar representers modules with extend.

# config/initializers/roar.rb

# When accidentally `extend`ing `nil` singleton with
# representer module it will be added to every `nil`
# (since it's a singleton).
# Representers override various methods that will cause bugs
# in weird places until next restart of ruby process
class NilClass
  def extend(*args)
    raise ArgumentError.new("Can't extend nil:NilClass")
  end
end

Sentry

Override sentry log level to distinguish between production and other (e.g. staging) environments

# config/initializers/raven.rb
class Raven::Event
  class << self
    def from_exception_with_level_override(exc, options = {}, &block)
      options[:level] ||= ENV["SENTRY_LOG_LEVEL"]
      from_exception_without_level_override(exc, options, &block)
    end

    alias_method_chain :from_exception, :level_override
  end
end

ENVied

ENVied ensure presence and type of app's ENV-variables. To make the bootstraping of the app a quick process, it allows to assign default values to them.

'Easily bootstrap' is quite the opposite of 'fail-fast when not all ENV-variables are present', hence it should be explicitly stated when defaults values are allowed:

# Envfile
development_or_test = ->{ ENV.fetch("RACK_ENV", "development").match(/development|test/) }
enable_defaults!(&development_or_test)

variable :HOST, :string, default: 'host.dev'
variable :SENTRY_DSN, :string, default: ''

variable :SSL_ENABLED, :boolean, default: false

variable :API_KEY, :string, default: "api_key"
variable :CONSUMER_KEY, :string, default: "consumer_key"

group :production do
  variable :FORCE_SSL, :boolean
end

The config enables the defaults in development or test environments, but still fail-fast in any other stage if any required ENV-variable is not set up.

Without the fallback to development in development_or_test rake tasks won't work.

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rails.md

rails.md

Rails guidelines

How to choose database

Setup generators

Remember to add indexes for foreign keys

Suggested gems for Rails applications

Setup proper redis namespaces

Rails cache store

Rails session store

Rack cache

Sidekiq

Faye server

Source maps

Redis

Mongodb

Add environment tag in Raven config

Configuration files

Remember to set reserved subdomains

Devise

If using gem from github put it under monterail organization

Disable Rack::Cache for rails < 4

localeapp pull policy

roar

Sentry

ENVied

Files

rails.md

Latest commit

History

rails.md

File metadata and controls

Rails guidelines

How to choose database

Setup generators

Remember to add indexes for foreign keys

Suggested gems for Rails applications

Setup proper redis namespaces

Rails cache store

Rails session store

Rack cache

Sidekiq

Faye server

Source maps

Redis

Mongodb

Add environment tag in Raven config

Configuration files

Remember to set reserved subdomains

Devise

If using gem from github put it under monterail organization

Disable Rack::Cache for rails < 4

localeapp pull policy

roar

Sentry

ENVied