[nodejs] [ANN] downgrade-identity: flexible helper method for downgrading process user/group id

I've recently been writing lots of little node services that mimic real
services and use privileged ports, and so I've been accumulating strategies
for
downgrading to a more restricted user after the ports been acquired via
process.setuid/setguid. There turns out to be enough subtlety in this
  (e.g. setuid("123") and setuid(123) are not at all the same thing) that I
decided to make it a stand-alone utility to maybe spare someone else a few
minutes of pain.

Details here https://github.com/femto113/node-downgrade-identity

By default it supports using SUDO environment variables and npm command
line arguments, so with a server.js like

     var server = require("http").createServer().on("listening",
require("downgrade-identity"));
     server.listen(80);

both

     % sudo node server.js

and

     % sudo npm start --setuid=something --setgid=something

"just work", and with a couple lines of code you can make it work with a
command line parser like optimist as well.