aws lambda shrink image test

shrink-test.js

console.log('Loading function');

var async = require("async");
var aws = require('aws-sdk');
var s3 = new aws.S3({ apiVersion: '2006-03-01' });
var gm = require("gm").subClass({imageMagick: true});
var fs = require("fs");
var mktemp = require("mktemp");

var THUMB_KEY_PREFIX = "lambda-test/",
    THUMB_WIDTH = 100,
    THUMB_HEIGHT = 100,
    ALLOWED_FILETYPES = ['png', 'jpg', 'jpeg', 'bmp', 'tiff', 'pdf', 'gif'];

var utils = {
    decodeKey: function(key) {
        return decodeURIComponent(key).replace(/\+/g, ' ');
    }
};

exports.handler = function(event, context) {
    //console.log('Received event:', JSON.stringify(event, null, 2));

    // Get the object from the event and show its content type
    var bucket = event.Records[0].s3.bucket.name;
    var srcKey = utils.decodeKey(event.Records[0].s3.object.key);
    var dstKey = THUMB_KEY_PREFIX + srcKey.replace(/\.\w+$/, ".jpg");
    var fileType = srcKey.match(/\.\w+$/);
    var params = {
        Bucket: bucket,
        Key: srcKey
    };
    s3.getObject(params, function(err, data) {
        if (err) {
            console.log(err);
            var message = "Error getting object " + srcKey + " from bucket " + bucket +
                ". Make sure they exist and your bucket is in the same region as this function.";
            console.log(message);
            context.fail(message);
        } else {
            console.log('CONTENT TYPE:', data.ContentType);
            console.log('Bucket:', bucket);
            console.log('srcKey:', srcKey);
            console.log('dstKey:', dstKey);
            console.log('fileType:', fileType);
            context.succeed(data.ContentType);
        }
    });

    async.waterfall(
        [
            // Download the image from S3
            function download(next) {
                console.log('in function:', 'download');
                s3.getObject({
                    Bucket: bucket,
                    Key: srcKey
                }, next);
            },
            // Shrink the image
            function createThumbnail(response, next) {
                console.log('in function:', 'createThumbnail');
                var temp_file, image;

                if(fileType === "pdf") {
                    temp_file = mktemp.createFileSync("/tmp/XXXXXXXXXX.pdf")
                    fs.writeFileSync(temp_file, response.Body);
                    image = gm(temp_file + "[0]");
                } else if (fileType === 'gif') {
                    temp_file = mktemp.createFileSync("/tmp/XXXXXXXXXX.gif")
                    fs.writeFileSync(temp_file, response.Body);
                    image = gm(temp_file + "[0]");
                } else {
                    image = gm(response.Body);
                }

                image.size(function(err, size) {
                    var scalingFactor = Math.min(THUMB_WIDTH / size.width, THUMB_HEIGHT / size.height),
                        width = scalingFactor * size.width,
                        height = scalingFactor * size.height;

                    this.resize(width, height)
                    .toBuffer("png", function(err, buffer) {
                        if(temp_file) {
                            fs.unlinkSync(temp_file);
                        }

                        if (err) {
                            next(err);
                        } else {
                            next(null, response.contentType, buffer);
                        }
                    });
                });
            },
            function uploadThumbnail(contentType, data, next) {
                console.log('in function:', 'uploadThumbnail');
                s3.putObject({
                    Bucket: bucket,
                    Key: dstKey,
                    Body: data,
                    ContentType: "image/png",
                    ACL: 'public-read',
                    Metadata: {
                        thumbnail: 'TRUE'
                    }
                }, next);
            }
        ],
        function(err) {
            if (err) {
                console.error(
                    "Unable to generate thumbnail for '" + bucket + "/" + srcKey + "'" +
                        " due to error: " + err
                );
            } else {
                console.log("Created thumbnail for '" + bucket + "/" + srcKey + "'");
            }

            context.done();
        }
    );
};