MaintenanceMode

This provides a simple interface to a "maintenance mode" toggle with optional maintenance message. It's not specific to maintenance mode, really, and could be used whenever a similar switch is needed.

Usage

MaintenanceMode.enable
MaintenanceMode.as_json # => { "enabled": true, "message": null }
MaintenanceMode.enable "we'll be back soon"
MaintenanceMode.as_json # => { "enabled": true, "message": "we'll be back soon" }
MaintenanceMode.enabled? # => true
MaintenanceMode.message # => "we'll be back soon"
MaintenanceMode.disable
MaintenanceMode.enabled? # => false

There is no magic here; if you want to apply this to your web app, just build a response handler with the result of MaintenanceMode.as_json or something to that effect.

There are also rake tasks to toggle MaintenanceMode:

rake maintenance:enable
rake maintenance:enable MESSAGE="Oh Noes!"
rake 'maintenance:enable[Oh Noes!]' # also works
rake maintenance:disable

To get these tasks, you'll have to add this line to your Rakefile:

# Rakefile
require 'maintenance_mode/rake_tasks'

Configuration

The persistence mechanism is configurable. Currently, the only one which ships with this gem just uses a file on disk.

Without configuration, the library will act on memory only (which of course means rake tasks have no effect on a server process). To configure the file-based persistence, use the following:

MaintenanceMode.persist_with :file, Rails.root.join('config/maintenance-mode')
# equivalent to
MaintenanceMode.persistence = MaintenanceMode::FilePersistence.new(
    Rails.root.join('config/maintenance-mode'))

n.b. The argument to FilePersistence must be a Pathname instead of merely a string.

Custom logic

You can set MaintenanceMode.persistence to any object which responds to the correct interface.

• enable(message=nil)
• disable
• enabled?
• message

Here's an example using Redis for persistence (this is untested; just for example):

class MyRedisMaintenancePersistence
  NULL = '__null__'

  def initialize(redis, key)
    @redis = redis
    @key = key
  end

  def enable(message=NULL)
    @redis.set @key, message
  end

  def disable
    @redis.del @key
  end

  def enabled?
    !!@redis.get(@key)
  end

  def message
    v = @redis.get(@key)
    v == NULL ? nil : v
  end
end

r = MyRedisMaintenancePersistence.new(Redis.new, 'maintenance-mode')
MaintenanceMode.persistence = r

# If writing as a separately distributed library, you could have your code
# register itself:
MaintenanceMode.register_persistence_method :redis, MyRedisMaintenancePersistence

# then people can use it via:
MaintenanceMode.persist_with :redis, Redis.new, 'maintenance-mode'

Contributing

Pull requests welcome.