@keg-hub/parse-config/src/utils/expand.js

Utils to allow loading non-javascript files into a node environment

const { isStr, exists } = require('@keg-hub/jsutils')

const EXPAND_MATCH = /(.?\${?(?:[a-zA-Z0-9_]+)?}?)/g

/**
 * Checks the passed in env for variable expansion similar to how terminal/bash works
 * @param {Object} envs - Parsed envs
 * @param {string|boolean} env - Env to be checked for expansion
 *
 * @example
 * process.env.SOME_ENV = 'some-value'
 * MY_ENV=${SOME_ENV} === MY_ENV='some-value'
 *
 * @returns {string|boolean} - Replaced value expanded as needed
 */
const convertValue = (envs, env) => {
  return (env.match(EXPAND_MATCH) || []).reduce((initialVal, match) => {
    const parts = /(.?)\${?([a-zA-Z0-9_]+)?}?/g.exec(match)
    const prefix = parts[1]

    let value
    let replacePart

    if (prefix === '\\') {
      replacePart = parts[0]
      value = replacePart.replace('\\$', '$')
    }
    else {
      const key = parts[2]
      replacePart = parts[0].substring(prefix.length)
      // Set precedence current envs then env file
      value = process.env[key] || envs[key] || ''
      // Check for recursive expansions
      value = convertValue(envs, value)
    }

    return initialVal.replace(replacePart, value)
  }, env)
}

/**
 * Checks the passed in env for variable expansion similar to how terminal/bash works
 * @param {Object} envs - Parsed envs
 *
 * @returns {Object} - Object with the envs expanded as needed
 */
const expand = envs => {
  return Object.keys(envs).reduce((acc, key) => {
    const val = exists(process.env[key]) ? process.env[key] : envs[key]
    acc[key] = isStr(val) ? convertValue(envs, val) : val

    return acc
  }, envs)
}

module.exports = {
  expand,
  convertValue,
}