postsetup.js

// Check to see if the user has Docker installed and which version of Python they prefer.

'use strict';
var inquirer = require('inquirer');
var chalk = require('chalk');
var YAML = require('js-yaml');
var fs = require('fs');

console.log(chalk.yellow('Hi, a few quick questions before we start:'));

var questions = [
  {
    type: 'list',
    name: 'python',
    message: 'What Python version?',
    choices: ['python2.7', 'python3.6'],
    filter: function (val) {
      return val.toLowerCase();
    }
  },
  {
    type: 'confirm',
    name: 'docker',
    message: 'Do you have Docker installed? Recommended, but not required.',
    default: true
  },
  {
    type: 'confirm',
    name: 'wantsDomain',
    message: 'Do you want to set up a custom domain? e.g. api.mycompany.com? Requires a domain in Route53.',
    default: false
  },
  {
    type: 'input',
    name: 'domainName',
    message: 'What is your domain name? e.g. api.mycompany.com',
    when: function(answers) {
      return answers.wantsDomain
    }
  },
]

inquirer.prompt(questions).then(function (answers) {
  
  var doc = YAML.safeLoad(fs.readFileSync('serverless.yml', 'utf8'));
  doc.custom.pythonRequirements.dockerizePip = answers.docker;
  doc.provider.runtime = answers.python;
  if (answers.wantsDomain) {
    doc.plugins.push('serverless-domain-manager');
    doc.custom.customDomain = createCustomDomain(answers.domainName);
  }
  saveServerlessYml(doc);
  console.log(chalk.yellow("All set! Run `sls deploy` to send your code to the cloud"));
  if (answers.wantsDomain) {
    console.log(chalk.yellow("Run `sls create_domain` to set up your custom domain."))
  }
});

const createCustomDomain = (domainName) => {
  return {
    domainName,
    basePath: '',
    stage: '${self:provider.stage}',
    createRoute53Record: true
  }
}

const saveServerlessYml = (config) => {
  /*
  When dumping to yml, it puts quotation marks around Serverless variables. This
  breaks variable resolution, so I clean it out after dumping to yml but before
  writing to the config file.
  */
  const dumped = YAML.dump(config);
  const cleaned = dumped.replace("\'${self:provider.stage}\'", "${self:provider.stage}")
  fs.writeFileSync('serverless.yml', cleaned);
}