AWS Lambda execute dynamic code

Question

Is it possible to define a NodeJs function which evaluates dynamic nodejs code?

Here is the context:

The user creates custom javascript function which should return true / false.

I need to "evaluate" the user code in a AWS Lambda container, which runs on NodeJs.

Is it possible?

Should i use something similar to javascript eval function?

EDIT

Here is what i tried

'use strict';

exports.handler = (event, context, callback) => {
    var body = "function test() { return 10; };";
    console.log("body", body);

    eval(body);

    var result = test();

    callback(null, result);
};

And i get an error saying "test" is not defined, therefore eval was not evaluated properly.

START RequestId: 6e9abd93-bd69-11e7-a43f-c75328d778e1 Version: $LATEST
2017-10-30T11:56:58.569Z    6e9abd93-bd69-11e7-a43f-c75328d778e1    body function test() { return 10; };
2017-10-30T11:56:58.581Z    6e9abd93-bd69-11e7-a43f-c75328d778e1    ReferenceError: test is not defined
    at exports.handler (/var/task/index.js:11:18)
END RequestId: 6e9abd93-bd69-11e7-a43f-c75328d778e1
REPORT RequestId: 6e9abd93-bd69-11e7-a43f-c75328d778e1  Duration: 32.78 ms  Billed Duration: 100 ms     Memory Size: 128 MB Max Memory Used: 19 MB  
RequestId: 6e9abd93-bd69-11e7-a43f-c75328d778e1 Process exited before completing request

Good question, I am contemplating the architectures of a system that needs to run customized user code and it’s good to know that Lambda is an option. — Matthew James Briggs
– Matthew James Briggs, Commented Nov 22, 2017 at 4:28
@MatthewJamesBriggs I find Lambda as a very good solution for this type of arhitecture. — Catalin
– Catalin, Commented Nov 22, 2017 at 14:17

user7401700 · Accepted Answer · 2017-11-02 18:40:25Z

1

eval works fine in Lambda. Remove the 'use strict' and it will work fine, outputting 10.

strict mode doesn't allow creating global variables, that's why you're getting the error.

A second option is to explicity add the function to the global context:

'use strict';

exports.handler = (event, context, callback) => {
    var body = "global.test = function() { return 10; };";
    console.log("body", body);

    eval(body);

    var result = test();

    callback(null, result);
};

answered Nov 2, 2017 at 18:40

user7401700

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Comments

Vijayanath Viswanathan · Accepted Answer · 2017-10-30 12:36:25Z

0

Node is just a runtime to execute javascript on the server side.You can write any valid Javascript code inside Node (Lambda).

As I could see in code 'eval' is not executing can you please try by installing the package 'npm install eval' - https://www.npmjs.com/package/eval

edited Oct 30, 2017 at 12:36

answered Oct 30, 2017 at 10:53

Vijayanath Viswanathan

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2 Comments

Mark B Over a year ago

@Catalin Then perhaps you should post the actual error or issue you are experiencing if it isn't working for you.

Vijayanath Viswanathan Over a year ago

Just to verify- can you please try installing the npm package 'npm install eval' and check. npmjs.com/package/eval

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