Duplicate environment config with pm2

[vitaly-t]

I've been using Node v20, passing it --env-file .env.dev in order to set environment variables.

Now, for some package scripts I need to add pm2 support. I see that pm2 forces me to place environment variables into ecosystem.config.js.

Now I have 2 copies of environment variables, ones to be used by pure NodeJS scripts, and ones used by PM2 scripts. I would think that PM2 should be smarter than that, and let us reuse what NodeJS supports natively, but I haven't been able to find how.

Is there a way to avoid duplication of environment configuration in this scenario? I really do not want to maintain environment config in 2 places because of PM2.

My package scripts now look like this:

    "start": "tsc && node --env-file .env.dev ./src/index.js channel=primary",
    "start-dev": "pm2 start ecosystem.config.js --env dev",
    "start-prod": "pm2 start ecosystem.config.js --env prod",

And so now I have to maintain the same environment variables inside .env.dev file, plus inside ecosystem.config.js file, which isn't good maintenance-wise.

[vitaly-t]

To resolve this, I had to add my own parser for reading the values.

Now my ecosystem.config.js file looks like this:

const fs = require('node:fs');

function loadConfig(file) {
    const txt = fs.readFileSync(file, 'utf-8');
    const m = txt.match(/(\w+)=(\w*)/g);
    return m.reduce((p, c) => {
        const s = c.split('=');
        return {...p, [s[0]]: s[1]}
    }, {});
}

const env_dev = loadConfig('env/.dev');
const env_prod = loadConfig('env/.prod');

module.exports = {
    apps: [
        {
            name: 'my-app',
            script: './src/index.js',
            args: 'patam1=123',
            watch: true,
            env_dev,
            env_prod
        }
    ]
}

I am hopeful, that PM2 would be able to do something like this automatically, to consume existing .env files and reuse them internally.