feds-cli/lib/config/envVars.js

CLI for Front-end Dev Stack

// This exists so that we can support the recieving of environment variables
// from multiple sources. i.e.
//  - standard environment variables
//  - a '.env' file, supported by  https://github.com/motdotla/dotenv
//
//  If a .env file exists, the contents of it will read and then it will be
//  merged over the standard environment variables object, otherwise the
//  standard environment variables object (process.env) will be used.
//
//  This gives us a nice degree of flexibility in deciding where we would
//  like our environment variables to be loaded from, which can be especially
//  useful for environment variables that we consider sensitive.

const fs = require('fs')
const pathResolve = require('path').resolve
const dotenv = require('dotenv')
const appRootPath = require('app-root-path').toString()
const envFile = pathResolve(appRootPath, './.env')
const envWhitelistFile = pathResolve(appRootPath, '.env_whitelist')

const whitelist = fs.readFileSync(envWhitelistFile, 'utf8')
  .split('\n')
  .filter(x => x.trim() !== '' && !x.startsWith('#'))

const mergedEnvVars = fs.existsSync(envFile)
  // We have a .env file, which we need to merge with the standard vars.
  ? Object.assign(
    {},
    // Merge the standard "process.env" environment variables object.
    process.env,
    // With the items from our ".env" file
    dotenv.parse(fs.readFileSync(envFile, 'utf8'))
  )
  // No .env file, so we will just use standard vars.
  : process.env

// Now we need to filter our mergedEnvVars to only contain environment
// variables that are deemed allowable by our .env_whitelist file.
const finalEnvVars = Object.keys(mergedEnvVars)
  .filter(key => whitelist.find(wkey => wkey === key))
  .reduce((acc, key) => {
    acc[key] = mergedEnvVars[key] // eslint-disable-line no-param-reassign
    return acc
  }, {})

// Guard that our some of our expected environment variables exist.
if (!finalEnvVars.BUNDLE_OUTPUT_PATH || !finalEnvVars.BUNDLE_ASSETS_FILENAME) {
  throw new Error('Some of the critical environment variables are missing, please ensure that you have provided them via the command line or via a .env file.')
}

module.exports = finalEnvVars