krystosterone / turnout

Turnout makes it easy to put Rack apps into maintenance mode

Turnout

Turnout is Rack middleware with a Ruby on Rails engine that allows you to easily put your app in maintenance mode.

Features

• Easy installation
• Rake commands to turn maintenance mode on and off
• Easily provide a reason for each downtime without editing the maintenance.html file
• Allow certain IPs or IP ranges to bypass the maintenance page
• Allow certain paths to be accessible during maintenance
• Easily override the default maintenance.html file with your own
• Simple YAML based config file for easy activation, deactivation and configuration without the rake commands
• Support for multiple maintenance page formats. Current HTML and JSON
• Supports Rails, Sinatra and any other Rack application
• Supports multiple maintenance file paths so that groups of applications can be put into maintenance mode at once.

Installation

Rails 3+

In your Gemfile add:

gem 'turnout'

then run

bundle install

Sinatra

In your Sinatra app file

require 'rack/turnout'

class App < Sinatra::Base
  configure do
    use Rack::Turnout

In your Rakefile

require 'turnout/rake_tasks'

Activation

rake maintenance:start

or

rake maintenance:start reason="Somebody googled Google!"

or

rake maintenance:start allowed_paths="/login,^/faqs/[0-9]*"

or

rake maintenance:start allowed_ips="4.8.15.16"

or

rake maintenance:start reason="Someone told me I should type <code>sudo rm -rf /</code>" allowed_paths="^/help,^/contact_us" allowed_ips="127.0.0.1,192.168.0.0/24"

or if you've configured named_maintenance_file_paths with a path named server

rake maintenance:server:start

Notes

• The reason parameter can contain HTML
• Multiple allowed_paths and allowed_ips can be given. Just comma separate them.
• All allowed_paths are treated as regular expressions.
• If you need to use a comma in an allowed_paths regular expression just escape it with a backslash: \,.
• IP ranges can be given to allowed_ips using CIDR notation.

Deactivation

rake maintenance:end

or if you activated with a named path like server

rake maintenance:server:end

Configuration

Turnout can be configured in two different ways:

1. Pass a config hash to the middleware

   use Rack::Turnout,
     app_root: '/some/path',
     named_maintenance_file_paths: {app: 'tmp/app.yml', server: '/tmp/server.yml'},
     default_maintenance_page: Turnout::MaintenancePage::JSON,
     default_reason: 'Somebody googled Google!',
     default_allowed_paths: ['^/admin/'],
     default_response_code: 418,
     default_retry_after: 3600

2. Using a config block

   Turnout.configure do |config|
     config.app_root = '/some/path'
     config.named_maintenance_file_paths = {app: 'tmp/app.yml', server: '/tmp/server.yml'}
     config.default_maintenance_page = Turnout::MaintenancePage::JSON
     config.default_reason = 'Somebody googled Google!'
     config.default_allowed_paths = ['^/admin/']
     config.default_response_code = 418
     config.default_retry_after = 3600
   end

NOTICE: Any custom configuration should be loaded not only in the app but in the rake task. This should happen automatically in Rails as the environment task is run if it exists. But you may want to create your own environment task in non-Rails apps.

Default Configuration

Turnout.configure do |config|
  config.app_root = '.'
  config.named_maintenance_file_paths = {default: config.app_root.join('tmp', 'maintenance.yml').to_s}
  config.default_maintenance_page = Turnout::MaintenancePage::HTML
  config.default_reason = "The site is temporarily down for maintenance.\nPlease check back soon."
  config.default_allowed_paths = []
  config.default_response_code = 503
  config.default_retry_after = 7200
end

Customization

Default maintenance pages are provided, but you can create your own public/maintenance.[html|json] files instead. If you provide a reason to the rake task, Turnout will parse the maintenance page file and attempt to replace a Liquid-style {{ reason }} tag with the provided reason. So be sure to include a {{ reason }} tag in your maintenance.html file.

Tips

There is no denied_paths feature because turnout denies everything by default. However you can achieve the same sort of functionality by using negative lookaheads with the allowed_paths setting, like so:

rake maintenance:start allowed_paths="^(?!/your/under/maintenance/path)"

A central named_maintenance_file_path can be configured in all your apps such as /tmp/turnout.yml so that all apps on a server can be put into mainteance mode at once. You could even configure service based paths such as /tmp/mongodb_maintenance.yml so that all apps using MongoDB could be put into maintenance mode.

Behind the Scenes

On every request the Rack app will check to see if tmp/maintenance.yml exists. If the file exists the maintenance page will be shown (unless allowed IPs are given and the requester is in the allowed range).

So if you want to get the maintenance page up or down in a hurry touch tmp/maintenance.yml and rm tmp/maintenance.yml will work.

Turnout will attempt to parse the maintenance.yml file looking for reason, allowed_ip and other settings. The file is checked on every request so you can change these values manually or just rerun the rake maintenance:start command.

Example maintenance.yml File

---
reason: Someone told me I should type <code>sudo rm -rf /</code>
allowed_paths:
- ^/help
- ^/contact_us
allowed_ips:
- 127.0.0.1
- 192.168.0.0/24
response_code: 503
retry_after: 3600