elastic-apm-node/lib/cloud-metadata/azure.js

The official Elastic APM agent for Node.js

/*
 * Copyright Elasticsearch B.V. and other contributors where applicable.
 * Licensed under the BSD 2-Clause License; you may not use this file except in
 * compliance with the BSD 2-Clause License.
 */

'use strict';
const URL = require('url').URL;
const { httpRequest } = require('../http-request');

const DEFAULT_BASE_URL = new URL('/', 'http://169.254.169.254:80');

/**
 * Checks for metadata server then fetches data
 *
 * The getMetadataAzure method will fetch cloud metadata information
 * from Amazon's IMDSv1 endpoint and return (via callback)
 * the formatted metadata.
 *
 * Before fetching data, the server will be "pinged" by attempting
 * to connect via TCP with a short timeout (`connectTimeoutMs`).
 *
 * https://docs.microsoft.com/en-us/azure/virtual-machines/windows/instance-metadata-service?tabs=windows
 */
function getMetadataAzure(
  connectTimeoutMs,
  resTimeoutMs,
  logger,
  baseUrlOverride,
  cb,
) {
  const baseUrl = baseUrlOverride || DEFAULT_BASE_URL;
  const options = {
    method: 'GET',
    timeout: resTimeoutMs,
    connectTimeout: connectTimeoutMs,
    headers: {
      Metadata: 'true',
    },
  };

  const url = baseUrl.toString() + 'metadata/instance?api-version=2020-09-01';

  const req = httpRequest(url, options, function (res) {
    const finalData = [];
    res.on('data', function (data) {
      finalData.push(data);
    });

    res.on('end', function (data) {
      let result;
      try {
        result = formatMetadataStringIntoObject(finalData.join(''));
      } catch (err) {
        logger.trace(
          'azure metadata server responded, but there was an ' +
            'error parsing the result: %o',
          err,
        );
        cb(err);
        return;
      }
      cb(null, result);
    });
  });

  req.on('timeout', function () {
    req.destroy(new Error('request to azure metadata server timed out'));
  });

  req.on('connectTimeout', function () {
    req.destroy(new Error('could not ping azure metadata server'));
  });

  req.on('error', function (err) {
    cb(err);
  });

  req.end();
}

/**
 * Builds metadata object
 *
 * Takes the response from /metadata/instance?api-version=2020-09-01
 * service request and formats it into the cloud metadata object
 */
function formatMetadataStringIntoObject(string) {
  const metadata = {
    account: {
      id: null,
    },
    instance: {
      id: null,
      name: null,
    },
    project: {
      name: null,
    },
    availability_zone: null,
    machine: {
      type: null,
    },
    provider: 'azure',
    region: null,
  };
  const parsed = JSON.parse(string);
  if (!parsed.compute) {
    return metadata;
  }
  const data = parsed.compute;
  metadata.account.id = String(data.subscriptionId);
  metadata.instance.id = String(data.vmId);
  metadata.instance.name = String(data.name);
  metadata.project.name = String(data.resourceGroupName);
  metadata.availability_zone = String(data.zone);
  metadata.machine.type = String(data.vmSize);
  metadata.region = String(data.location);

  return metadata;
}

module.exports = { getMetadataAzure };