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
}

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!