gcp-metadata

What is gcp-metadata?

The gcp-metadata npm package is a library that allows users to query Google Cloud Platform's (GCP) metadata service for information about the currently running instance and project. This can be useful for applications that need to understand their environment within GCP, such as retrieving instance attributes or project details.

What are gcp-metadata's main functionalities?

Instance Metadata

Retrieve metadata of the current GCP instance. This includes details like the instance ID, zone, and custom metadata.

const gcpMetadata = require('gcp-metadata');

async function getInstanceMetadata() {
  if (await gcpMetadata.isAvailable()) {
    const instanceMetadata = await gcpMetadata.instance();
    console.log(instanceMetadata);
  }
}
getInstanceMetadata();

Project Metadata

Fetch metadata of the current GCP project. This can include project-wide attributes like project ID and numeric project number.

const gcpMetadata = require('gcp-metadata');

async function getProjectMetadata() {
  if (await gcpMetadata.isAvailable()) {
    const projectMetadata = await gcpMetadata.project();
    console.log(projectMetadata);
  }
}
getProjectMetadata();

Check Metadata Server Availability

Determine if the GCP metadata server is available and reachable from the instance.

const gcpMetadata = require('gcp-metadata');

async function checkAvailability() {
  const isAvailable = await gcpMetadata.isAvailable();
  console.log('Metadata service available:', isAvailable);
}
checkAvailability();

Other packages similar to gcp-metadata

aws-sdk

The AWS SDK for JavaScript allows developers to interact with AWS services. It includes a module for querying the AWS EC2 instance metadata service, which is similar to what gcp-metadata does for GCP.

README

GCP Metadata: Node.js Client

Get the metadata from a Google Cloud Platform environment

A comprehensive list of changes in each version may be found in the CHANGELOG.

• GCP Metadata Node.js Client API Reference
• GCP Metadata Documentation
• github.com/googleapis/gcp-metadata

Read more about the client libraries for Cloud APIs, including the older Google APIs Client Libraries, in Client Libraries Explained.

Table of contents:

• Quickstart

  • Installing the client library
  • Using the client library

• Samples

• Versioning

• Contributing

• License

Quickstart

Installing the client library

npm install gcp-metadata

Using the client library

const gcpMetadata = require('gcp-metadata');

async function quickstart() {
  // check to see if this code can access a metadata server
  const isAvailable = await gcpMetadata.isAvailable();
  console.log(`Is available: ${isAvailable}`);

  // Instance and Project level metadata will only be available if
  // running inside of a Google Cloud compute environment such as
  // Cloud Functions, App Engine, Kubernetes Engine, or Compute Engine.
  // To learn more about the differences between instance and project
  // level metadata, see:
  // https://cloud.google.com/compute/docs/storing-retrieving-metadata#project-instance-metadata
  if (isAvailable) {
    // grab all top level metadata from the service
    const instanceMetadata = await gcpMetadata.instance();
    console.log('Instance metadata:');
    console.log(instanceMetadata);

    // get all project level metadata
    const projectMetadata = await gcpMetadata.project();
    console.log('Project metadata:');
    console.log(projectMetadata);
  }
}

quickstart();

Check to see if the metadata server is available

const isAvailable = await gcpMetadata.isAvailable();

Access all metadata

const data = await gcpMetadata.instance();
console.log(data); // ... All metadata properties

Access specific properties

const data = await gcpMetadata.instance('hostname');
console.log(data); // ...Instance hostname
const projectId = await gcpMetadata.project('project-id');
console.log(projectId); // ...Project ID of the running instance

Access nested properties with the relative path

const data = await gcpMetadata.instance('service-accounts/default/email');
console.log(data); // ...Email address of the Compute identity service account

Access specific properties with query parameters

const data = await gcpMetadata.instance({
  property: 'tags',
  params: { alt: 'text' }
});
console.log(data) // ...Tags as newline-delimited list

Access with custom headers

await gcpMetadata.instance({
  headers: { 'no-trace': '1' }
}); // ...Request is untraced

Take care with large number valued properties

In some cases number valued properties returned by the Metadata Service may be too large to be representable as JavaScript numbers. In such cases we return those values as BigNumber objects (from the bignumber.js library). Numbers that fit within the JavaScript number range will be returned as normal number values.

const id = await gcpMetadata.instance('id');
console.log(id)  // ... BigNumber { s: 1, e: 18, c: [ 45200, 31799277581759 ] }
console.log(id.toString()) // ... 4520031799277581759

Environment variables

• GCE_METADATA_HOST: provide an alternate host or IP to perform lookup against (useful, for example, you're connecting through a custom proxy server).

  For example:

  export GCE_METADATA_HOST = '169.254.169.254'
  

• DETECT_GCP_RETRIES: number representing number of retries that should be attempted on metadata lookup.

• DEBUG_AUTH: emit debugging logs

• METADATA_SERVER_DETECTION: configure desired metadata server availability check behavior.

  • assume-present: don't try to ping the metadata server, but assume it's present
  • none: don't try to ping the metadata server, but don't try to use it either
  • bios-only: treat the result of a BIOS probe as canonical (don't fall back to pinging)
  • ping-only: skip the BIOS probe, and go straight to pinging

Samples

Samples are in the samples/ directory. Each sample's README.md has instructions for running its sample.

Sample	Source Code	Try it
Quickstart	source code

The GCP Metadata Node.js Client API Reference documentation also contains samples.

Supported Node.js Versions

Our client libraries follow the Node.js release schedule. Libraries are compatible with all current active and maintenance versions of Node.js. If you are using an end-of-life version of Node.js, we recommend that you update as soon as possible to an actively supported LTS version.

Google's client libraries support legacy versions of Node.js runtimes on a best-efforts basis with the following warnings:

• Legacy versions are not tested in continuous integration.
• Some security patches and features cannot be backported.
• Dependencies cannot be kept up-to-date.

Client libraries targeting some end-of-life versions of Node.js are available, and can be installed through npm dist-tags. The dist-tags follow the naming convention legacy-(version). For example, npm install gcp-metadata@legacy-8 installs client libraries for versions compatible with Node.js 8.

Versioning

This library follows Semantic Versioning.

This library is considered to be General Availability (GA). This means it is stable; the code surface will not change in backwards-incompatible ways unless absolutely necessary (e.g. because of critical security issues) or with an extensive deprecation period. Issues and requests against GA libraries are addressed with the highest priority.

More Information: Google Cloud Platform Launch Stages

Contributing

Contributions welcome! See the Contributing Guide.

Please note that this README.md, the samples/README.md, and a variety of configuration files in this repository (including .nycrc and tsconfig.json) are generated from a central template. To edit one of these files, make an edit to its templates in directory.

License

Apache Version 2.0

See LICENSE