I'm trying to follow the AWS guide for S3 and Lambda here
http://docs.aws.amazon.com/lambda/latest/dg/with-s3-example.html
I'm at the manual testing stage, but I get "errorMessage": "Process exited before completing request" when I try to run the test.
In the log the fail point is something to do with the async.waterfall code.
When I run the Lambda function, it does get my example image, resize it and puts it into the new S3 bucket. Then it looks like async is trying to find an undefined "nextTask" to run. I've never used async before, so I'm not sure how to fix this.
The cloudwatch log file gives me this
2016-09-16T18:36:44.011Z 836d0280-7c3c-11e6-933a-9b5b3a5e8dd8 TypeError: undefined is not a function
at /var/task/ResizeImages.js:98:13
at /var/task/node_modules/async/dist/async.js:486:20
at nextTask (/var/task/node_modules/async/dist/async.js:5008:33)
at Response.<anonymous> (/var/task/node_modules/async/dist/async.js:5015:17)
at Response.<anonymous> (/var/task/node_modules/async/dist/async.js:339:31)
at Response.<anonymous> (/var/task/node_modules/async/dist/async.js:847:20)
at Request.<anonymous> (/var/runtime/node_modules/aws-sdk/lib/request.js:355:18)
at Request.callListeners (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:105:20)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/sequential_executor.js:77:10)
at Request.emit (/var/runtime/node_modules/aws-sdk/lib/request.js:615:14)
To install async (and imageMagik), I just used the command
npm install async gm
inside my node_modules folder.
The example node script I have used is here, line 98 is commented.
// dependencies
var async = require('async');
var AWS = require('aws-sdk');
var gm = require('gm')
.subClass({ imageMagick: true }); // Enable ImageMagick integration.
var util = require('util');
// constants
var MAX_WIDTH = 100;
var MAX_HEIGHT = 100;
// get reference to S3 client
var s3 = new AWS.S3();
exports.handler = function(event, context, callback) {
// 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 + "-resized";
var dstKey = "thumb-" + srcKey;
// Sanity check: validate that source and destination are different buckets.
if (srcBucket == dstBucket) {
callback("Source and destination buckets are the same.");
return;
}
// Infer the image type.
var typeMatch = srcKey.match(/\.([^.]*)$/);
if (!typeMatch) {
callback("Could not determine the image type.");
return;
}
var imageType = typeMatch[1];
if (imageType != "jpg" && imageType != "png") {
callback('Unsupported image type: ${imageType}');
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;
// 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
);
}
callback(null, "message");
} // ------- LINE 98 -----------
);
};
