How do you write to the file system of an aws lambda instance?

Modifying your code into the Lambda template worked for me. I think you need to assign a function to exports.handler and call the appropriate context.succeed() or context.fail() method. Otherwise, you just get generic errors.

var fs = require("fs");exports.handler = function(event, context) {    fs.writeFile("/tmp/test.txt", "testing", function (err) {        if (err) {            context.fail("writeFile failed: " + err);        } else {            context.succeed("writeFile succeeded");        }    });};

So the answer lies in the context.fail() or context.succeed() functions. Being completely new to the world of aws and lambda I was ignorant to the fact that calling any of these methods stops execution of the lambda instance.

According to the docs:

The context.succeed() method signals successful execution and returns a string.

By eliminating these and only calling them after I had run all the code that I wanted, everything worked well.

I ran into this, and it seems like AWS Lambda may be using an older (or modified) version of fs. I figured this out by logging the response from fs.writeFile and noticed it wasn't a promise.

To get around this, I wrapped the call in a promise:

var promise = new Promise(function(resolve, reject) {    fs.writeFile('/tmp/test.txt', 'testing', function (err) {        if (err) {            reject(err);        } else {            resolve();        }    });});

Hopefully this helps someone else :hug-emoji: