yktv4/kraken-node

Official Kraken module for Node.js

Node.js module for Kraken.io API

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

• Installation
• Getting Started
• Downloading Images
• How To Use
• Wait and Callback URL
  • Wait Option
  • Callback URL
• Authentication
• Usage - Image URL
• Usage - Image Upload
• Lossy Optimization
• Image Resizing
• WebP Compression
• Amazon S3 and Rackspace Cloud Files Integration
  • Amazon S3
  • Rackspace Cloud Files

Installation

npm install kraken --save

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.io's image optimization API in your applications.

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. Optimized images are available on our servers for one hour only, after which they are permanently deleted.

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 online yet.

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 the callback_url option set the results will be posted to the URL specified in your request.

Wait option

With the wait option turned on for every request to the API, the connection will be held open unil the image has been optimized. Once this is done you will get an immediate response with a JSON object containing your optimization results. To use this option simply set "wait": true in your request.

Request:

{
    "auth": {
        "api_key": "your-api-key",
        "api_secret": "your-api-secret"
    },
    "url": "http://awesome-website.com/images/header.jpg",
    "wait": true
}

Response

{
    "success": true,
    "file_name": "header.jpg",
    "original_size": 324520,
    "kraked_size": 165358,
    "saved_bytes": 159162,
    "kraked_url": "http://dl.kraken.io/d1aacd2a2280c2ffc7b4906a09f78f46/header.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 over 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:

{
    "auth": {
        "api_key": "your-api-key",
        "api_secret": "your-api-secret"
    },
    "url": "http://image-url.com/file.jpg",
    "callback_url": "http://awesome-website.com/kraken_results"
}

Response:

{
    "id": "18fede37617a787649c3f60b9f1f280d"
}

Results posted to the Callback URL:

{
    "id": "18fede37617a787649c3f60b9f1f280d"
    "success": true,
    "file_name": "file.jpg",
    "original_size": 324520,
    "kraked_size": 165358,
    "saved_bytes": 159162,
    "kraked_url": "http://dl.kraken.io/18fede37617a787649c3f60b9f1f280d/file.jpg"
}

Authentication

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

var Kraken = require('kraken');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

Usage - Image URL

To optimize an image by providing image URL use the kraken.url() method. You will need to provide two mandatory parameters - url to the image and wait or callback_url:

var Kraken = require('kraken');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

var opts = {
    url: 'http://image-url.com/file.jpg',
    wait: true
};

kraken.url(opts, function(err, data) {
    if (err) {
        console.log('Failed. Error message: %s', err);
    } else {
        console.log('Success. Optimized image URL: %s', data.kraked_url);
    }
});

Depending on a choosen response option (Wait or Callback URL) in the 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:

{
    success: true,
    file_name: 'file.jpg',
    original_size: 30664,
    kraked_size: 577,
    saved_bytes: 30087,
    kraked_url: 'http://dl.kraken.io/d1aacd2a2280c2ffc7b4906a09f78f46/file.jpg'
}

If no saving were found, the API will return an object containing "success":true and will report saved_bytes of 0:

{
    success: true,
    saved_bytes: 0,
}

Usage - Image Upload

If you want to upload your images directly to Kraken API use the kraken.upload() method. You will need to provide two mandatory parameters - file which is either a string containing a path to the file or a Stream Object and wait or callback_url.

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

var Kraken = require('kraken'),
    fs = require('fs');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

var opts = {
    file: fs.createReadStream('file.jpg'),
    wait: true
};

kraken.upload(opts, function (err, data) {
    if (err) {
        console.log('Failed. Error message: %s', err);
    } else {
        console.log('Success. Optimized image URL: %s', data.kraked_url);
    }
});

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:

var opts = {
    file: '/path/to/image/file.jpg',
    lossy: true,
    wait: 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 its vast array of optimization algorithms. The resize option needs a few parameters to be passed like desired width and/or height and a mandatory strategy property. For example:

var Kraken = require('kraken');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

var opts = {
    file: '/path/to/image/file.jpg',
    wait: true,
    resize: {
        width: 100,
        height: 75,
        strategy: 'crop'
    }
};

kraken.upload(opts, function(err, data) {
    if (err) {
        console.log('Failed. Error message: %s', err);
    } else {
        console.log('Success. Optimized image URL: %s', data.kraked_url);
    }
});

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:

var opts = {
    file: '/path/to/image/file.jpg',
    wait: true,
    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 additional 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.
• region - Name of the region your S3 bucket is located in.

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:

var Kraken = require('kraken');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

var opts = {
    file: '/path/to/image/file.jpg',
    wait: true,
    s3_store: {
        key: 'your-amazon-access-key',
        secret: 'your-amazon-secret-key',
        bucket: 'destination-bucket',
        region: 'us-east-1'
    }
};

kraken.upload(opts, function(err, data) {
    if (err) {
        console.log('Failed. Error message: %s', err);
    } else {
        console.log('Success. Optimized image URL: %s', data.kraked_url);
    }
});

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

{
    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:

var Kraken = require('kraken');

var kraken = new Kraken({
    api_key: 'your-api-key',
    api_secret: 'your-api-secret'
});

var opts = {
    file: '/path/to/image/file.jpg',
    wait: true,
    cf_store: {
        user: 'your-rackspace-username',
        key: 'your-rackspace-api-key',
        container: 'destination-container'
    }
};

kraken.upload(opts, function(err, data) {
    if (err) {
        console.log('Failed. Error message: %s', err);
    } else {
        console.log('Success. Optimized image URL: %s', data.kraked_url);
    }
});

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:

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:

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.