Put env file while building in electron packed app

I need to put a .env file into a packed app while building, then attach variables from the .env to process.env. I put the .env in the same directory as the package.json and it works when I start electron from npm. It won't work when I build a MacOS app and start it (it seems as though the .env file is lost).

My main.js starts a java backend, so I provide environment variables:

// This works in npm start, but not for packed app
process.env.MY_VAR = dotenv.config().parsed.MY_VAR;

this.serverProcess = require("child_process").spawn(
    "/usr/bin/env",
    ["sh", dirname + "/server/bin/embedded"],
    { env: process.env });

My case is:

• Generate .env and put it to electron folder (it generates automatically by build system)
• Build electron and pack electron

electron-builder --mac --publish never

• Start MacOS App
• Packed app should run java with the provided environment (from .env)

Is there an example or best practices how to put environmental variables while package building?

dotenvExpand did the trick.

const dotenvExpand = require("dotenv-expand");

if (process.resourcesPath) {
    dotenvExpand.expand(dotenv.config({ path: path.join(process.resourcesPath, ".env") }));
}