Node.js run MongoDB from within application

You can look into starting a subprocess. So letting Node run mongo as an external program. This way you could create a new mongodb instance for any user that fits that criteria. You can use for example the node "child process" library and use the spawn function to 'spawn' a new database instance by writing there the console command as already stated by Larry Turtis or here mongodb - multiple instances. It could look like this, to start the instance:

const spawn = require('child_process').spawn;
const pipe = spawn('mongod', ['--dbpath=<LOCATION>', '--port', '<PORT>'])

You can pipe console output to node with this:

    pipe.stdout.on('data', function (data) {
        printback(data.toString('utf8'));
    });

    pipe.stderr.on('data', (data) => {
        printback(data.toString('utf8'));
    });

    pipe.on('close', (code) => {
        callback('Process exited with code: '+ code);
    });

And kill the mongodb running instance by keeping the pipe reference and then doing this:

static end_pipe(pipe) {
    pipe.kill('SIGINT');
}

The command to boot mongoDB is available on the NPM mongodb page. Adding --fork and --logpath because I assume you want it to start in the background.

mongod --dbpath=/data --port 27017 --fork --logpath /var/log/mongod.log

You could just include this as part of your npm start script in package.json:

"scripts": {"start": "mongod --dbpath=/data --port 27017 --fork --logpath /var/log/mongod.log"}