AWS lambda never completes but doesn't appear to timeout either - node.js

Question

I'm attempting to create a simple application. A user emails an attachment to a special inbox, AWS SES gets the email and stores it in S3, a lambda function is triggered and the lambda finds the email in S3, parses out the attachment (in this case a jpg) and then stores it in a different S3 bucket. Finally, the application creates a new row in an Airtable with the image as an attachment.
When I invoked this function locally using serverless, everything works fine. The email with the image are already stored in an S3 bucket so I've created a mock which passes the key explicitly to my lambda. However, when I deploy the application and send a test email, the following happens:
Email is stored in S3 bucket 'to-airtable-temp'
Lambda function is called
Before the email can be found and the attachment striped off and stored in a seperate S3 bucket the function just stops. No error message or timeout. It just stops. Cloudwatch logs look like the following:
START RequestId: 6a0364ae-0879-4ee1-9dcd-c8747de1a650 Version: $LATEST
2020-02-17T07:39:55.465Z 6a0364ae-0879-4ee1-9dcd-c8747de1a650 INFO {
s3SchemaVersion: '1.0',
configurationId: 'emailtoairtable-dev-parse-224c3963d3a3f9c35018ae93a9fffea4',
bucket: {
name: 'to-airtable-temp',
ownerIdentity: { principalId: 'AI5RGHFD5AFHE' },
arn: 'arn:aws:s3:::to-airtable-temp'
},
object: {
key: 'mtvuuiokqj55l2a8b0qser7tn9dhfignoh9c1vg1',
size: 3804230,
eTag: 'c821fb0a2a9c3b060e20e7d177f8b972',
sequencer: '005E4A434810147365'
}
}
2020-02-17T07:39:55.465Z 6a0364ae-0879-4ee1-9dcd-c8747de1a650 INFO key mtvuuiokqj55l2a8b0qser7tn9dhfignoh9c1vg1
2020-02-17T07:39:55.465Z 6a0364ae-0879-4ee1-9dcd-c8747de1a650 INFO Key pushed to list. mtvuuiokqj55l2a8b0qser7tn9dhfignoh9c1vg1
END RequestId: 6a0364ae-0879-4ee1-9dcd-c8747de1a650
REPORT RequestId: 6a0364ae-0879-4ee1-9dcd-c8747de1a650 Duration: 1113.17 ms Billed Duration: 1200 ms Memory Size: 1024 MB Max Memory Used: 114 MB Init Duration: 119.56 ms
Here is my handler.js file:
'use strict';
module.exports.parse = async event => {
try {
const aws = require('aws-sdk');
const s3 = new aws.S3();
const simpleParser = require('mailparser').simpleParser;
const Airtable = require('airtable');
const dateformat = require('dateformat');
var base = new Airtable({ apiKey: process.env.airtableApiKey}).base(process.env.airtableBaseId);
var data = [];
var keys = [];
event["Records"].forEach(async record => {
console.log(record["s3"]);
console.log('key', record["s3"]["object"]["key"]);
keys.push(record["s3"]["object"]["key"]);
console.log('Key pushed to list. ', record["s3"]["object"]["key"]); // <-- this is the last line that I am sure processes because I see it in the CloudWatch logs.
var temp_data = await s3.getObject(
{
Bucket: 'to-airtable-temp',
Key: record["s3"]["object"]["key"]
}).promise();
console.log('temp_data', temp_data);
data.push(temp_data);
});
setTimeout( async function() {
// console.log('data', data[0].Body.toString());
let parsed = await simpleParser(data[0].Body.toString());
console.log(parsed);
// save the file to a public S3 bucket so it can be uploaded to airtable
parsed["attachments"].forEach(function(attachment) {
let now = new Date();
s3.upload({
Bucket: 'to-airtable-images',
Key: keys[0] + dateformat(now, "yyyy-mm-dd") + '.jpg',
Body: attachment.content,
ContentType: "image/jpeg"
},
function(error, data) {
if (error) {
throw error;
}
console.log('File uploaded successfully. ' +data.Location);
// Now upload to airtable
base('Input').create([
{
"fields": {"Attachments": [
{
"url": data.Location
}
]}
}
], function(err, records) {
if (err) {
console.error(err);
return;
}
records.forEach(function (record) {
console.log(record.getId());
});
});
});
});
return {
statusCode: 200,
body: JSON.stringify(
{
message: 'Go Serverless v1.0! Your function executed successfully!',
input: event,
data: JSON.stringify(data),
},
null,
2
),
};
}, 500); // I've tried increasing this time but it still hangs.
} catch (error) {
console.error(error);
}
};

Answer 1

You shouldn't use async/await with the forEach function. Using async/await with a forEach loop. Instead, use the more modern for of syntax:
for (let record of event["Records"]) {
// you can include await calls in this block
}