Lambda#edge takes more than 30 seconds - amazon-web-services

Question

I have a lambda functions in one AZ in EU and another one in us-east-1 to be used via CloudFront triggers.
CloudFront --> #edge function -> lambda function
Sometimes, it takes a while for the second lambda invoke to be finished which hits the lambda#edge limits. It would be fine if it happens in async but I don't see any results when I run it async. Here is the code:
"use strict";
const AWS = require("aws-sdk");
AWS.config.update({
region: "eu-west-1",
});
const querystring = require("querystring");
exports.handler = async (event, context) => {
let request = event.Records[0].cf.request;
let params = querystring.parse(request.querystring);
if (params.key) {
const payload = {
/* my payload */
};
const lambda_params = {
FunctionName: "lambda-func-name",
Payload: JSON.stringify(payload),
};
const lambda = new AWS.Lambda();
const resp= await lambda.invoke(lambda_params);
console.log("Finished");
} else {
// allow the response to pass through
return {
"status":404,
"body":"an error"
}
}
};
the second lambda func would process some images and putting the results in the S3, but when I call it async, I don't see any results. Am I missing something?

Answer 1

First of all, a lengthy runtime seems like a very bad use case for Lambda#Edge. Maybe you should redesign your system to handle that.
Please note that Lambda#Edge has a function timeout limit of maximum 30 seconds in case of origin events and only 5 seconds for viewer events. Moreover, there is a compute utilization limit:
CloudFront Functions have a limit on the time they can take to run,
measured as compute utilization. Compute utilization is a number
between 0 and 100 that indicates the amount of time that the function took to run as a percentage of the maximum allowed time. For example, a compute utilization of 35 means that the function completed in 35% of the maximum allowed time.
With respect to your current design, in order to invoke Lambda asynchronously the invoke function should specify the correct invocation type argument. So instead
const lambda_params = {
FunctionName: "lambda-func-name",
Payload: JSON.stringify(payload),
};
you should use
const lambda_params = {
FunctionName: "lambda-func-name",
InvocationType: "Event", // <= you are missing this parameter
Payload: JSON.stringify(payload),
};
By default, the InvocationType value is set to RequestResponse. This means synchronous invocation. See docs for reference.