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// dependencies | |
var async = require('async'); | |
var path = require('path'); | |
var AWS = require('aws-sdk'); | |
var gm = require('gm') | |
.subClass({ imageMagick: true }); // Enable ImageMagick integration. | |
var util = require('util'); | |
// constants | |
var MAX_WIDTH = 640; | |
var MAX_HEIGHT = 100; | |
// get reference to S3 client | |
var s3 = new AWS.S3(); | |
exports.handler = function(event, context) { | |
// Read options from the event. | |
console.log("Reading options from event:\n", util.inspect(event, {depth: 5})); | |
var srcBucket = event.Records[0].s3.bucket.name; | |
// Object key may have spaces or unicode non-ASCII characters. | |
var srcKey = | |
decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " ")); | |
var dstBucket = srcBucket; | |
var dstKey = srcKey.replace('originals', 'resized'); | |
var extension = path.extname(dstKey); | |
var filename = path.basename(dstKey, extension); | |
var directory = path.dirname(dstKey); | |
dstKey = directory + '/' + filename + extension; | |
// Sanity check: validate that source and destination are different buckets. | |
// if (srcBucket == dstBucket) { | |
// console.error("Destination bucket must not match source bucket."); | |
// return; | |
// } | |
console.log('Dumping resized file to: ' + dstKey); | |
// Infer the image type. | |
var typeMatch = srcKey.match(/\.([^.]*)$/); | |
if (!typeMatch) { | |
console.error('unable to infer image type for key ' + srcKey); | |
return; | |
} | |
var imageType = typeMatch[1]; | |
if (imageType != "jpg" && imageType != "png") { | |
console.log('skipping non-image ' + srcKey); | |
return; | |
} | |
// Download the image from S3, transform, and upload to a different S3 bucket. | |
async.waterfall([ | |
function download(next) { | |
// Download the image from S3 into a buffer. | |
s3.getObject({ | |
Bucket: srcBucket, | |
Key: srcKey | |
}, | |
next); | |
}, | |
function transform(response, next) { | |
gm(response.Body).size(function(err, size) { | |
// Infer the scaling factor to avoid stretching the image unnaturally. | |
var scalingFactor = Math.min( | |
MAX_WIDTH / size.width, | |
MAX_HEIGHT / size.height | |
); | |
var width = scalingFactor * size.width; | |
var height = scalingFactor * size.height; | |
// var height = scalingFactor * size.height; | |
// Transform the image buffer in memory. | |
this.resize(width, height) | |
.toBuffer(imageType, function(err, buffer) { | |
if (err) { | |
next(err); | |
} else { | |
next(null, response.ContentType, buffer); | |
} | |
}); | |
}); | |
}, | |
function upload(contentType, data, next) { | |
// Stream the transformed image to a different S3 bucket. | |
s3.putObject({ | |
Bucket: dstBucket, | |
Key: dstKey, | |
Body: data, | |
ContentType: contentType | |
}, | |
next); | |
} | |
], function (err) { | |
if (err) { | |
console.error( | |
'Unable to resize ' + srcBucket + '/' + srcKey + | |
' and upload to ' + dstBucket + '/' + dstKey + | |
' due to an error: ' + err | |
); | |
} else { | |
console.log( | |
'Successfully resized ' + srcBucket + '/' + srcKey + | |
' and uploaded to ' + dstBucket + '/' + dstKey | |
); | |
} | |
context.done(); | |
} | |
); | |
}; |
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