Upgrading to ES6

[Akxe]

I would be also very good to use new ES6 syntax, it could upgrade performance in many cases. Improve number of needed modules, and would bring new features.

() => {} functions to stop from binding this to self
Promise to remove dependency on waterfall
Map has forEach method, could give you easy aliasing for hostnames
const, let to specify scopes and usage
and probably many more

[Irrelon]

This is true, having it written with ES6 would be nice, but I challenge the part about performance... the gains (if any) would probably be so small as to make the rewrite pointless unless we are missing a feature in ES5 that we desperately need and is only available in ES6.

I'm not against ES6 per-se, just that if it's not broken, don't fix it comes to mind :)

[Akxe]

Loading many libraries can be intense for small server machines, I agree that for normal computer it doesn't really change that much, but for raspberry pi server, it could change a lot.

I can rewrite most of it to es6, but the certbot is problem for me as I don't know what it is. If you want me to rewrite it I can look onto it and create a pull afterwards.

[Irrelon]

Certbot is letsencrypt for cli.