Configure cypress.io using dotenv-extended, and getenv

cypress-plugins-index.js

// ***********************************************************
// https://on.cypress.io/plugins-guide
// ***********************************************************
const dotenv = require('dotenv-extended')
const getenv = require('getenv')

dotenv.load()

const overrideBaseUrl = () => {
  let baseUrl = getenv.string('CYPRESS_BASE_URL', '')
  if (!baseUrl) {
    const scheme = getenv.bool('DEV_HTTPS') ? 'https://' : 'http://'
    const host = getenv.string('DEV_HOST')
    const port = getenv.string('DEV_PORT')
    baseUrl = `${scheme}${host}:${port}`
  }
  return baseUrl
}

// This function is called when a project is opened or re-opened (e.g. due to
// the project's config changing)
module.exports = (on, config) => {
  config.baseUrl = overrideBaseUrl()
  return config
}

You might need to return config... I'm not sure what we do if return undefined. You're mutating config so it may just work, but ideally you make it clear that config is the return value.

Sorry, I just realized this in the docs (you MUST return config if you want modifications to be included)...realized you commented here as well. You are correct! Updated!