Lambda to create EMR Cluster don't fire the cluster creation

Question

I'm trying to run a λ code that creates a cluster, but nothing happens, maybe I'm misunderstanding the usage on Node (since I'm not that familiar with it.)

The function is as simple as:

// configure AWS Dependecies
var AWS = require('aws-sdk');

exports.handler = function(event, context) {
    // EMR Client
    var emr = new AWS.EMR({apiVersion: '2009-03-31', region: 'us-east-1'});

    var params = {... dozens of params describing jobs ...};
    var AWSRequest = emr.runJobFlow(params);
    AWSRequest
        .on('success', function(response){ console.log("success => " + response)})
        .on('error', function(response){ console.log("error => " + response)})
        .on('complete', function(response){ console.log("complete => "  + response)})
        .send( function(err, data){
            if (err) console.log(err, err.stack); // an error occurred
            else     console.log(data);           // successful response
        });

    context.done(null, 'λ Completed');
};

I'm testing it with the grunt-aws-lambda grunt task and in the console, but nothing shows except for:

aws-emr-lambda$ grunt lambda_invoke
Running "lambda_invoke:default" (lambda_invoke) task

Message
-------
λ Completed

Done, without errors.

Executing it from the AWS console results in the same output and no EMR Cluster is created.

Any thoughts on this?

Answer 1

AWSRequest sends requests asynchronously, but you are calling context.done in your main handler. This means that at best this is going to send the request but not wait for a response. context.done needs to be in the send callback or AWS will likely terminate the function before the response is received, or perhaps even before it is sent, depending on how the request is performed within the AWS SDK.

exports.handler = function(event, context) {
    // EMR Client
    var emr = new AWS.EMR({apiVersion:'2009-03-31', region:'us-east-1'});

    var params = {... dozens of params describing jobs ...};
    var AWSRequest = emr.runJobFlow(params);
    AWSRequest
        .on('success', function(response){ console.log("success => " + response)})
        .on('error', function(response){ console.log("error => " + response)})
        .on('complete', function(response){ console.log("complete => "  + response)})
        .send( function(err, data){
            if (err) console.log(err, err.stack); // an error occurred
            else     console.log(data);           // successful response
            context.done(null,'λ Completed');
        });
};