Invoke function async on AWS Lambda

invoke returns an AWS.Request instance, which is not automatically going to perform a request. It's a representation of a request which is not sent until send() is invoked.

That's why the latter version works but the former does not. The request is sent when .promise() is invoked.

// a typical callback implementation might look like this
lambda.invoke({
    FunctionName: 'rock-function',
    InvocationType: 'Event',
    Payload: JSON.stringify({
        queryStringParameters: {
            id: c.id,
            template: c.csvTemplate,
        },
    }),
}, (err, data) => {
    if (err) {
        console.log(err, err.stack);
    } else {
        console.log(data);
    }
});

// ... or you could process the promise() for the same result
lambda.invoke({
    FunctionName: 'rock-function',
    InvocationType: 'Event',
    Payload: JSON.stringify({
        queryStringParameters: {
            id: c.id,
            template: c.csvTemplate,
        },
    }),
}).promise().then(data => {
    console.log(data);
}).catch(function (err) {
    console.error(err);
});