Update ecosystem2.config.js for cluster mode

[rvolz]

Enables pm2 to have direct access to the app and to control it better than before.

Using npm to start the app caused pm2 to fork it, and therefore pm2 had only control over the npm process, but not the kiwi app itself. To get rid of npm:

• replace the npm call with the script script: "./src/launch.mjs"
• add the npm modules to the node path NODE_PATH: "./node_modules"
• add the -r switch to node_args node_args: "-r dotenv/config --max-old-space-size=XXXX"

Since cluster mode can scale the app, it is important to add instances: 1 to disable scaling.
Another advantage of this approach is, that we now can use max_memory_restart: "XXXXM" to tell pm2 to restart the app when the memory limits are reached.

[rvolz]

Update: the only change I could see when running the kiwi node in cluster mode was that the main thread caused more system load.

[TimDaub]

This is a great find, thanks!