Rack-delay

A simple rack middleware to add a random delay for requests, so you can simulate network latency during development. This library works with any rack capable framework, so you can use with sinatra or rails or whatever you want.

You can install this library via gem

gem install rack-delay

or via Bundler adding

gem 'rack-delay'

to your Gemfile and install:

bundle install

To use rack-delay simply add it in config.ru file. Below is an example of middleware:

# config.ru

require 'rack/delay'

use Rack::Delay

app = proc do |env|
  [ 200, {'Content-Type' => 'text/plain'}, "b" ]
end

run app

Rack-delay when use without options, will add a random delay to every request. You probably want to customize this behaviour, so you can pass options to middleware ex:

# config.ru

require 'rack/delay'

use Rack::Delay, {
  :min => 0,    # ms
  :max => 5000, # ms
  :if => lambda { |request|
    request.xhr?
  }
}

app = proc do |env|
  [ 200, {'Content-Type' => 'text/plain'}, "b" ]
end

run app

In previous example rack-delay will add a random delay (between :min/:max) to every ajax requests.

Also you can do more complex things like use a different delay for different requests, ex:

# config.ru

require 'rack/delay'

use Rack::Delay, {
  :delay => lambda { |request|
    if request.get? # fixed 100ms delay to every get request
      [100]
    elsif request.post? # 300ms - 3sec delay to every post request
      [300, 3000]
    else
      [0, rand(5000)] # use a random delay
    end
    
    # if you not return a number from this block, rack-delay will use defaults range :min/:max to calc random delay
  },
  :if => lambda { |request|
    request.xhr? and request.ip == '127.0.0.1'
  }
}

app = proc do |env|
  [ 200, {'Content-Type' => 'text/plain'}, "b" ]
end

run app

Here a list of options which rack-delay can understand.

• :min / :max
  Specifies range in msec of random delay. When :min == :max delay will be fixed

• :delay
  Another way to customize delay generation. Value returned by block can be a single number or 2 item array.
  When a number, then the request will be slowdown exactly by that number msec.
  If returns 2 items array (eg. [min, max]), then will be used to build range.

• :if / :unless
  Used to control activation of rack-delay.

Copyright (c) 2013 Vincenzo Farruggia.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.