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Ruby Gem for Kraken.io API

With this Ruby Gem you can plug into the power and speed of Kraken.io Image Optimizer.

Installation

Add this line to your application's Gemfile:

gem 'kraken-io'

And then execute:

$ bundle

Or install it yourself as:

$ gem install kraken-io

Getting Started

First you need to sign-up for the Kraken API and obtain your unique API Key and API Secret. You will find both under API Credentials. Once you have set up your account, you can start using Kraken API in your applications. You can test integration without charge by signing up for the Developers plan.

Authentication

The first step is to authenticate to Kraken API by providing your unique API Key and API Secret while creating new Kraken instance:

require 'rubygems'
require 'kraken-io'

kraken = Kraken::API.new(
    :api_key => 'your-api-key',
    :api_secret => 'your-api-secret'
)

How to use

You can optimize your images in two ways - by providing an URL of the image you want to optimize or by uploading an image file directly to Kraken API.

The first option (image URL) is great for images that are already in production or any other place on the Internet. The second one (direct upload) is ideal for your deployment process, build script or the on-the-fly processing of your user's uploads where you don't have the images available on-line yet.

Usage - Image URL

To optimize an image by providing an image URL use the kraken.url() method. You will need to provide an url to the image, and optionally a callback_url. If you don't provide a callback_url, then wait will be set to true automatically:

data = kraken.url('http://image-url.com/file.jpg')

if data.success
    puts 'Success! Optimized image URL: ' + data.kraked_url
else
    puts 'Fail. Error message: ' + data.message
end

Depending on if you perform a synchronous request or use a callback URL, in the returned data object you will find either the optimization ID or optimization results containing a success property, file name, original file size, kraked file size, amount of savings and optimized image URL:

data.success       #=> true,
data.file_name     #=> "file.jpg"
data.original_size #=> 30664
data.kraked_size   #=> 577
data.saved_bytes   #=> 30087
data.kraked_url    #=> "http://dl.kraken.io/d1aacd2a2280c2ffc7b4906a09f78f46/file.jpg"

If no savings were found, the API will return an object containing "success":false and a proper error message:

data.success #=> false
data.message #=> "This image can not be optimized any further"

Usage - Image Upload

If you want to upload your images directly to Kraken API use the kraken.upload() method. You will need to provide an absolute path to the file, and optionally, an options hash with a callback_url.

In the data object you will find the same optimization properties as with url option above.

data = kraken.upload('/path/to/image/file.jpg')

if data.success
    puts 'Success! Optimized image URL: ' + data.kraked_url
else
    puts 'Fail. Error message: ' + data.message
end

Wait and Callback URL

Kraken gives you two options for fetching optimization results. With the wait option set the results will be returned immediately in the response. With callback_url the results will be posted to the URL specified in your request. Unless a callback_url is set in the options, the kraken gem will use the wait option by default to perform synchronous processing.

Wait option

By default, the wait option is turned on for every request to the API, and the connection will be held open until the image has been optimized. Once this is finished you will get an immediate response with a Ruby object containing your optimization results.

Request:

data = kraken.url('http://awesome-website.com/images/file.jpg')

Response

data.success       #=> true
data.file_name     #=> "file.jpg"
data.original_size #=> 324520
data.kraked_size   #=> 165358
data.saved_bytes   #=> 159162
data.kraked_url    #=> "http://dl.kraken.io/d1aacd2a2280c2ffc7b4906a09f78f46/file.jpg"

Callback URL

With the Callback URL the HTTPS connection will be terminated immediately and a unique id will be returned in the response body. After the optimization is finished, Kraken will POST a message to the callback_url specified in your request. The ID in the response will reflect the ID in the results posted to your Callback URL.

We recommend requestb.in as an easy way to capture optimization results for initial testing.

Request:

params = {
    :callback_url => 'http://awesome-website.com/kraken_results'
}

data = kraken.url('http://awesome-website.com/images/header.jpg', params)

Response:

data.id #=> "18fede37617a787649c3f60b9f1f280d"

Results posted to the Callback URL:

def kraken_results
  params[:id]            #=> "18fede37617a787649c3f60b9f1f280d"
  params[:success]       #=> true
  params[:file_name]     #=> "header.jpg"
  params[:original_size] #=> 324520
  params[:kraked_size]   #=> 165358
  params[:saved_bytes]   #=> 159162
  params[:kraked_url]    #=> "http://dl.kraken.io/18fede37617a787649c3f60b9f1f280d/header.jpg"
end

If you want to set a callback_url to be used for all subsequent requests coming from a kraken instance, you can set it like this:

kraken.callback_url('http://awesome-website.com/kraken_results')
data = kraken.url('http://awesome-website.com/images/header.jpg')

Downloading Images

Remember - never link to optimized images offered to download. You have to download them first, and then replace them in your websites or applications. Due to security reasons optimized images are available on our servers for one hour only. You can copy them back to your application with open-uri like so:

require 'open-uri'

if request.success
    File.write('local_file_name.jpg', open(data.kraked_url).read, { :mode => 'wb' })
end

Lossy Optimization

When you decide to sacrifice just a small amount of image quality (usually unnoticeable to the human eye), you will be able to save up to 90% of the initial file weight. Lossy optimization will give you outstanding results with just a fraction of image quality loss.

To use lossy optimizations simply set "lossy" => true in your request:

kraken.upload('/path/to/image/file.jpg', 'lossy' => true)

PNG Images

PNG images will be converted from 24-bit to paletted 8-bit with full alpha channel. This process is called PNG quantization in RGBA format and means the amout of colours used in an image will be reduced to 256 while maintaining all information about alpha transparency.

JPEG Images

For lossy JPEG optimizations Kraken will generate multiple copies of a input image with a different quality settings. It will then intelligently pick the one with the best quality to filesize ration. This ensures your JPEG image will be at the smallest size with the highest possible quality, without the need for a human to select the optimal image.

Image Resizing

Image resizing option is great for creating thumbnails or preview images in your applications. Kraken will first resize the given image and then optimize it with it's vast array of optimization algorythms. The resize option needs a few parameters to be passed like desired width and/or height and a mandatory strategy property. For example:

params = {
    'resize' => {
        'width' => 100,
        'height' => 75,
        'strategy' => 'crop'
    }
}

data = kraken.upload('/path/to/image/file.jpg', params)

if data.success
    puts 'Success! Optimized image URL: ' + data.kraked_url
else
    puts 'Fail. Error message: ' + data.message
end

The strategy property can have one of the following values:

  • exact - Resize by exact width/height. No aspect ratio will be maintained.
  • portrait - Exact width will be set, height will be adjusted according to aspect ratio.
  • landscape - Exact height will be set, width will be adjusted according to aspect ratio.
  • auto - The best strategy (portrait or landscape) will be selected for a given image according to aspect ratio.
  • crop - This option will crop your image to the exact size you specify with no distortion.

WebP Compression

WebP is a new image format introduced by Google in 2010 which supports both lossy and lossless compression. According to Google, WebP lossless images are 26% smaller in size compared to PNGs and WebP lossy images are 25-34% smaller in size compared to JPEG images.

To recompress your PNG or JPEG files into WebP format simply set "webp": true flag in your request JSON. You can also optionally set "lossy": true flag to leverage WebP's lossy compression:

params = {
    'webp' => true,
    'lossy' => true
}

Amazon S3 and Rackspace Cloud Files

Kraken API allows you to store optimized images directly in your S3 bucket or Cloud Files container. With just a few addidtional parameters your optimized images will be pushed to your external storage in no time.

Amazon S3

Mandatory Parameters:

  • key - Your unique Amazon "Access Key ID".
  • secret - Your unique Amazon "Secret Access Key".
  • bucket - Name of a destination container on your Amazon S3 account.

Optional Parameters:

  • path - Destination path in your S3 bucket (e.g. "images/layout/header.jpg"). Defaults to root "/".
  • acl - Permissions of a destination object. This can be "public_read" or "private". Defaults to "public_read".

The above parameters must be passed in a s3_store object:

params = {
    's3_store' => {
        'key' => 'your-amazon-access-key',
        'secret' => 'your-amazon-secret-key',
        'bucket' => 'destination-bucket'
    }
}

data = kraken.upload('/path/to/image/file.jpg', params)

if data.success
    puts 'Success! Optimized image URL: ' + data.kraked_url
else
    puts 'Fail. Error message: ' + data.message
end

The data object will contain kraked_url method pointing directly to the optimized file location in your Amazon S3 account:

data.kraked_url #=> "http://s3.amazonaws.com/YOUR_CONTAINER/path/to/file.jpg"

Rackspace Cloud Files

Mandatory Parameters:

  • user - Your Rackspace username.
  • key - Your unique Cloud Files API Key.
  • container - Name of a destination container on your Cloud Files account.

Optional Parameters:

  • path - Destination path in your container (e.g. "images/layout/header.jpg"). Defaults to root "/".

The above parameters must be passed in a cf_store object:

params = {
    'cf_store' => {
        'user' => 'your-rackspace-username',
        'key' => 'your-rackspace-api-key',
        'container' => 'destination-container'
    }
}

data = kraken.upload('/path/to/image/file.jpg', params)

if data.success
    puts 'Success! Optimized image URL: ' + response.kraked_url
else
    puts 'Fail. Error message: ' + data.message
end

If your container is CDN-enabled, the optimization results will contain kraked_url which points directly to the optimized file location in your Cloud Files account, for example:

data.kraked_url #=> "http://e9ffc04970a269a54eeb-cc00fdd2d4f11dffd931005c9e8de53a.r2.cf1.rackcdn.com/path/to/file.jpg"

If your container is not CDN-enabled kraked_url will point to the optimized image URL in the Kraken API:

data.kraked_url #=> "http://dl.kraken.io/ecdfa5c55d5668b1b5fe9e420554c4ee/file.jpg"

LICENSE - MIT

Copyright (c) 2013 Nekkra UG

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.

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