build dynamic ansible inventory from vagrant multi vm

vagrant_inventory.js

#!/usr/bin/env node
"use strict";
/**
 * Run as follows: ansible-playbook -i ./vagrant_inventory.js pbook.yml,
 * NB requires the 'vagrant hostsupdater plugin'
 */
//=============================================================================
/**
 * Get list of vagrant hosts
 */
//=============================================================================
function get_vagrant_hosts() {
  const
    fs = require('fs'),
    HOSTS_FILE_string = fs.readFileSync('/etc/hosts', 'utf8'),
    HOSTS_FILE_array = HOSTS_FILE_string.split('\n'),
    vagrant_match = /vagrant/i;
  let vagrant_hosts = [];
  HOSTS_FILE_array.forEach(registered_host => {
    if(registered_host.search(vagrant_match) != -1) {
      let registered_host_params = registered_host.split(' ');
      const
        registered_host_ip = registered_host_params[0],
        registered_host_name = registered_host_params[2];
      vagrant_hosts.push([registered_host_ip, registered_host_name]);
    }
  });
  return vagrant_hosts;
}
//=============================================================================
/**
 * Get ip address of running vagrant host
 */
function get_ip_address(host, list) {
  let ip;
  list.forEach(host_stats => {
    const
      NAME = host_stats[1],
      IP = host_stats[0];
    if(NAME == host) {
      ip = IP;
    }
  });
  return ip;
}
//=============================================================================
/**
 * Get list of running vagrant hosts
 */
//=============================================================================
function main() {
  const
    cp = require('child_process'),
    registered_hosts = get_vagrant_hosts(),
    running_hosts = cp.execFile('vagrant', ['status', '--machine-readable'],
      function (err, stdout, stderr) {
        if(err) {
          console.log('There was an error executing vagrant');
          console.error(err);
          return process.exit(2);
        }
        else {
          if(stdout) {
  //=============================================================================
  /**
   * Build hosts and groups objects
   */
  //=============================================================================
            let
              hosts = [],
              groups = {"web": {"hosts": []}, "lb": {"hosts": []}, "db": {"hosts": []}},
              main_output = {"infra": {"hosts": hosts}, "_meta": {"hostvars": {}}},
              vagrant_hosts_status_list = stdout.split('\n');
            vagrant_hosts_status_list.forEach(function (host_status) {
              const host_status_params = host_status.split(',');
              let
                host_name = host_status_params[1],
                host_status_key = host_status_params[2],
                host_state = host_status_params[3];
              if(host_status_key == 'state' && host_state == 'running') {
                hosts.push(host_name);
                let
                  web_match = /^app\d{1,}$/i,
                  lb_match = /^lb\d{1,}$/i,
                  db_match = /^db\d{1,}$/i;
                if(host_name.search(web_match) != -1) {
                  groups["web"]["hosts"].push(host_name);
                  let web_ip = get_ip_address(host_name, registered_hosts);
                  main_output["_meta"]["hostvars"][host_name] = {"ip": web_ip};
                }
                else if(host_name.search(db_match) != -1) {
                  groups["db"]["hosts"].push(host_name);
                  let db_ip = get_ip_address(host_name, registered_hosts);
                  main_output["_meta"]["hostvars"][host_name] = {"ip": db_ip};
                }
                else if(host_name.search(lb_match) != -1) {
                  groups["lb"]["hosts"].push(host_name);
                  let lb_ip = get_ip_address(host_name, registered_hosts);
                  main_output["_meta"]["hostvars"][host_name] = {"ip": lb_ip};
                }
              }
            });
            for(const grp in groups) {
              main_output[grp] = groups[grp];
            }
            process.stdout.write(JSON.stringify(main_output, null, 2)  + '\n');
            process.exit(0);
          }
          else if(stderr) {
            process.stdout.write(JSON.stringify(stderr, null, 2) + '\n');
            process.exit(1);
          }
        }
      });
}
//=============================================================================
if (require.main === module) {
  main();
}
//=============================================================================