Simple AWS Lambda function to process an image using imageMagik and dump to S3 (triggered by S3 PUT)

aws-lambda-nodejs-S3imageprocessing.js

'use strict';
var AWS = require('aws-sdk');
//var im = require('imagemagick');
var im = require("gm").subClass({ imageMagick: true });
var fs = require('fs');
var async = require('async');
 
 // DEBUGGING
// console.log('ENV VARS:');
// console.log('-----------------------');
// console.log(JSON.stringify(process.env));
// console.log('-----------------------');

//AWS Configurations (not sure why I have to set these)
AWS.config.update({region: 'us-east-1'});
AWS.config.update({sessionToken:process.env.AWS_SESSION_TOKEN, accessKeyId: process.env.AWS_ACCESS_KEY_ID, secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY});

// get reference to S3 client 
var s3 = new AWS.S3();
 
// response object returned from the lambda function
var output = [];
var inbucket = process.env.S3INBUCKET;
var outbucket = process.env.S3OUTBUCKET;

//-----------------------------------------------------------------------------
const process_image = (image_key) => {
    console.log('started processing a image - ' + image_key);
    
    var get_params = {Bucket:inbucket, Key:image_key};
    s3.getObject(get_params, function(err, response) {
        if (err) {
            console.log('Failed to download the file - ' + image_key);
            console.log(err, err.stack);
        }
        else {
            console.log('Successfully downloaded the file - ' + image_key);
            const dest_key = 'mo-' + image_key
            console.log('START image operation for - ' + dest_key);
            var filename = dest_key.replace(/^.*[\\\/]/, '');
            var newFile = "/tmp/" + filename; 
            
            try {
	            // the operation to process the image and save to /tmp/[newFile]
	            var image = im(response.Body).negative().write(newFile, function (err) {
	  				if (err) { 
	  					console.log('FAILED to process the image - ' + dest_key);
	  				} else {
	  					// image processed, push it to S3 bucket
			            var new_image_content = new Buffer(fs.readFileSync(newFile));
			            var put_params = {Bucket: outbucket, Key: dest_key, Body: new_image_content, ContentType: response.ContentType};
			            s3.putObject(put_params, function (err) {
			                if (err)
			                {
			                    console.log('Failed to upload the file - ' + dest_key);
			                    console.log(err, err.stack);
			                }
			                else
			                {
			                    console.log('SUCCESS sent the processed image to S3 outbound bucket - ' + dest_key);
			                    var result = {};
			                    result.dest_key = dest_key;
			                    result.status = true;
			                    output.push(result);
			                    
			                    //Delete the created tmp file
			                    try {
			                        fs.unlinkSync(newFile);
			                    } catch (err) {
			                        console.log('FAILED to unlink the temporary file - ' + newFile);
			                    }
			                    console.log('DONE processing and cleanup for - ' + dest_key);
			                }
			            });
	  				}
				});
        	} catch (err) {
        		console.log('ERROR - GraphicsMagik operation failed:', err);
    		}
        }
    });
}

//-----------------------------------------------------------------------------
exports.handler = (event, context, callback) => {
    // DEBUGGING
    console.log('Received event:', JSON.stringify(event, null, 2));
    console.log('Exec Env =' + process.env.AWS_EXECUTION_ENV);
    console.log('remaining time =', context.getRemainingTimeInMillis());
    console.log('functionName =', context.functionName);
    console.log('AWSrequestID =', context.awsRequestId);
    console.log('logGroupName =', context.logGroupName);
    console.log('logStreamName =', context.logStreamName);
    console.log('Entered handler function will dump into ' + outbucket); 
    var image_key = event.Records[0].s3.object.key;
    process_image(image_key);
    callback(null, output);
};