serverless-cf-vars/lib/replaceChildNodes.js

Allows you to use Cloudformation pseudo parameters and substitute in other variables in your serverless.yml.

/*eslint no-template-curly-in-string: "off"*/
/*eslint no-cond-assign: "off"*/

var _ = require('lodash')
var keyStem = 'serverlesscfvarsplugin'
var searchRe = new RegExp(keyStem + '(\\d+)')

/**
 * Some plugins try to clean up ${}-tags
 * This step finds our #{} and replace them with alpha numeric text.
 * This should allow our tags to slip past "helpful" cleanup attempts.
 */
function step0(dictionary, insideSub, ivars = {}) {
  const vars = Object.assign({}, ivars)
  const resources = _.transform(dictionary, function(acc, val, key) {
    insideSub = insideSub || key === 'Fn::Sub'
    if (_.isPlainObject(val) || _.isArray(val)) {
      const result = step0(val, insideSub, vars)
      Object.assign(vars, result.vars)
      acc[key] = result.resources
      return
    }
    if (typeof val === 'string') {
      var matches, cfkey
      while (matches = val.match(/#{([^}]+)}/)) {
        cfkey = keyStem + Object.keys(vars).length
        vars[cfkey] = matches[1]
        val = val.replace(/#{[^}]+}/, cfkey)
      }
      if (cfkey) {
        acc[key] = insideSub ? val : { 'Fn::Sub': val }
        return
      }
    }
    acc[key] = val
  })
  return {resources, vars}
}

/**
 * Let's convert the strings that step0 produced into ${}
 */
function step1(dictionary, vars) {
  const resources = _.transform(dictionary, function(acc, val, key) {
    if (_.isPlainObject(val) || _.isArray(val)) {
      acc[key] = step1(val, vars)
      return
    }
    if (typeof val === 'string') {
      var matches, cfkey, cfvalue
      while (matches = val.match(searchRe)) {
        cfkey = keyStem + matches[1]
        cfvalue = vars[cfkey]
        val = val.replace(cfkey, '${'+cfvalue+'}')
      }
      if (cfkey) {
        acc[key] = val
        return
      }
    }
    acc[key] = val
  })
  return resources
}

/**
 * Custom resources aren't available until now, so they haven't been replaced in step0.
 * Let's replace any #{} that exist at this point.
 */
function step2(dictionary, insideSub) {
  return _.transform(dictionary, function(acc, val, key) {
    insideSub = insideSub || key === 'Fn::Sub'
    if (_.isPlainObject(val) || _.isArray(val)) {
      acc[key] = step2(val, insideSub)
      return
    }
    if (typeof val === 'string' && val.search(/#{([^}]+)}/) !== -1) {
      const newValue = val.replace(/#{([^}]+)}/g, '${$1}')
      acc[key] = insideSub ? newValue : { 'Fn::Sub': newValue }
      return
    }
    acc[key] = val
  })
}

module.exports = {
  step0,
  step1,
  step2
}