Retrieve metadata about the host EC2 instance

ec2-instance-info.js

var P = require('bluebird');
var request = P.promisify(require('request'));
P.promisifyAll(request);

exports.currentInstanceInfo = currentInstanceInfo;

var INSTANCE_BASE_URL = 'http://169.254.169.254/2014-11-05/';

currentInstanceInfo().then(res => console.dir(res));

function currentInstanceInfo() {
  return P.props({
    'ami-id': instanceGet('meta-data/ami-id'),
    'ami-launch-index': instanceGet('meta-data/ami-launch-index'),
    'ami-manifest-path': instanceGet('meta-data/ami-manifest-path'),
    'availability-zone': instanceGet('meta-data/placement/availability-zone'),
    'block-device-mapping': getBlockDevices(),
    'instance-action': instanceGet('meta-data/instance-action'),
    'instance-id': instanceGet('meta-data/instance-id'),
    'instance-identity': instanceGetJSON('dynamic/instance-identity/document'),
    'instance-type': instanceGet('meta-data/instance-type'),
    'local-hostname': instanceGet('meta-data/local-hostname'),
    'local-ipv4': instanceGet('meta-data/local-ipv4'),
    'mac': instanceGet('meta-data/mac'),
    'public-hostname': instanceGet('meta-data/public-hostname'),
    'public-ipv4': instanceGet('meta-data/public-ipv4'),
    'public-keys': getPublicKeys(),
    'reservation-id': instanceGet('meta-data/reservation-id'),
    'security-groups': instanceGet('meta-data/security-groups'),
    'user-data': instanceGet('user-data')
  });
}

function getBlockDevices() {
  var BLOCK_URL = 'meta-data/block-device-mapping/';

  return instanceGet(BLOCK_URL)
  .then(body => body.split('\n'))
  .then(aliases => {
    var obj = {};
    aliases.forEach(alias => obj[alias] = instanceGet(BLOCK_URL + alias));
    return P.props(obj);
  });
}

function getPublicKeys() {
  var KEY_URL = 'meta-data/public-keys/';

  return instanceGet(KEY_URL)
  .then(body => body.split('\n'))
  .then(indexesToNames => {
    var obj = {};
    indexesToNames.forEach(i2n => {
      var parts = i2n.split('=');
      var index = parts[0];
      var name = parts[1];

      obj[name] = instanceGet(KEY_URL + index + '/')
        .then(body => body.split('\n'))
        .then(keyTypes => {
          var keys = {};
          keyTypes.forEach(keyType => keys[keyType] = instanceGet(KEY_URL + index + '/' + keyType));
          return P.props(keys);
        });
      return P.props(obj);
    });
    return P.props(obj);
  });
}

function instanceGet(endpoint) {
  return request.getAsync(INSTANCE_BASE_URL + endpoint)
  .then(res => res.statusCode === 200 ? res.body : null);
}

function instanceGetJSON(endpoint) {
  return request.getAsync(INSTANCE_BASE_URL + endpoint)
  .then(res => JSON.parse(res.body));
}