Chore: Script to start Rocket.Chat in HA mode during development

[d-gubert]

Proposed changes (including videos or screenshots)

Sometimes we need to start Rocket.Chat in High-Availability mode (cluster) during development to test how a feature behaves or hunt down a bug. Currently, this involves a lot of commands with details that might be lost if you haven't done it in a while.

This PR intends to provide a really simple way for us to start many instances of Rocket.Chat connected in a cluster.

How to

To start up a cluster, you need to first start the "main" instance. This will be started just like you'd do with a single server in development - with the meteor command, running on port 3000. To do it, run npm run ha.

Then, when you want to add an instance to the cluster, go to another terminal and run npm run ha:add. This will start another server on port 3030, providing all necessary parameters for it to correctly connect to the "main" instance and forming a cluster. If you want to add even more servers, you will need to provide a different port manually, like so: PORT=3050 npm run ha:add.

There is, of course, a lot of room for improvement, but it makes the DevEx much smoother when compared to starting the other instances manually with a big line passing a lot of environment variables to the command.

Issue(s)

Steps to test or reproduce

Further comments

[geekgonecrazy]

Why have we never done this before? Thats genius! So much easier then doing manually