node-modman

Module Manager

Installation

npm i modman

What is it?

Modman is a module that lets you control Node.js modules in a sandbox, based off of "vm2".

You can control any module/package, from simply disallowing usage of some FS functions, to controlling how NPM packages can be used in code.

How do I use it?

Here is a basic example:

var modman = require('modman');
var sandbox = modman({
  permissions: {
    "fs.unlinkSync": false,
    "fs.unlink": false,
    "fs.readFileSync": true,
    "fs.readFile": true,
    "fs.writeFileSync": true,
    "fs.writeFile": true
  },
  modules: ['@colors/colors']
});

sandbox(function(){
  var colors = require('@colors/colors')
  var fs = require('fs');

  console.log(colors.blue('Hello, World!')); // "Hello, World!" in blue color
  fs.unlinkSync('index.js'); // gives error
})

Let's break this down.

"permissions": {
    "fs.unlinkSync": false,
    "fs.unlink": false,
    "fs.readFileSync": true,
    "fs.readFile": true,
    "fs.writeFileSync": true,
    "fs.writeFile": true
}

The "permissions" entry is an object filled with the module and functions that have permissions set.

All entry names are the modules, followed by a dot, followed by the function to control.

If a function is denied access, when it is ran, it will say this and stop execution of the sandbox:

Error: Function not allowed in this context.
    at Object.ota.<computed>.<computed> [as unlinkSync] (/home/runner/sanel/index.js:21:52)
    at ReadOnlyHandler.apply (/home/runner/sanel/node_modules/vm2/lib/bridge.js:479:11)
    at vm.js:5:6
    at vm.js:6:3
    at BaseHandler.apply (/home/runner/sanel/node_modules/vm2/lib/bridge.js:479:11)
    at NodeVM.run (/home/runner/sanel/node_modules/vm2/lib/nodevm.js:425:23)
    at /home/runner/sanel/index.js:73:18
    at Object.<anonymous> (/home/runner/sanel/index.js:90:1)
    at Module._compile (node:internal/modules/cjs/loader:1101:14)

However, if it is allowed, you can use it as normal.

If a permission is not defined, then the function cannot be used. To make it usable, set the permission to true.

  modules: ['@colors/colors']

The "modules" array is so you can include certain modules in the sandbox. It is recommended to use this only for custom modules, as you can include built-ins using the "permissions" entry.

sandbox(function(){
  var colors = require('@colors/colors')
  var fs = require('fs');

  console.log(colors.blue('Hello, World!')); // "Hello, World!" in blue color
  fs.unlinkSync('index.js'); // gives error
})

The "sandbox" function is from the permissions and external modules we set. When run, it will run the code inside the function inside the sandbox, and not run it using fn(). No variables outside the code can be used in the sandbox.

Documentation

modman()

modman({...})

Returns: function

Arguments: (1): array

• permissions: required
• modules: optional

sandbox(function)

sandbox(function(){
  ...
})

Returns: nothing

Arguments: (1): function