The Node.js runtime

Preview — Cloud Run functions

This feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of the Service Specific Terms. Pre-GA features are available "as is" and might have limited support. For more information, see the launch stage descriptions.

Your Cloud Run function runs in an environment consisting of an operating system version with add-on packages, language support, and the Node.js Functions Framework library that supports and invokes your function. This environment is identified by the language version, and is known as the runtime ID.

Function preparation

You can prepare a function directly from the Google Cloud console or write it on your local machine and upload it. To prepare your local machine for Node.js development, see Set up a Node.js development environment.

Select your runtime

Cloud Run functions supports several versions of Node.js, listed on the Supported language runtimes and base images page. You can select the preferred Node.js runtime for your function during deployment:

gcloud

To use Cloud Run functions to deploy an HTTP function using the gcloud CLI, see Deploy using the Google Cloud CLI.

Console

If you're using the Google Cloud console, select the runtime when you create and deploy your function. See the Google Cloud console quickstart for detailed instructions.

Source code structure

For Cloud Run functions to find your function's definition, your source code must follow a specific structure. See Write Cloud Run functions for more information.

Specify dependencies

You can specify dependencies for your functions by listing them in a package.json file. For more information, see Specify dependencies in Node.js.

NPM build script

By default, the Node.js runtime executes npm run build if a build script is detected in package.json. If you require additional control over your build steps before starting your application, you can provide a custom build step by adding a gcp-build script to your package.json file.

You can prevent your build from running the npm run build script by either:

• Adding a gcp-build script with an empty value in your package.json file: "gcp-build":"".

• Setting the build environment variable GOOGLE_NODE_RUN_SCRIPTS to the empty string to prevent all scripts from running.

Asynchronous function completion

When working with asynchronous tasks that involve callbacks or Promise objects, you must explicitly inform the runtime that your function has finished executing these tasks. You can do this in several different ways, as shown in the following samples. The key is that your code must wait for the asynchronous task or Promise to complete before returning; otherwise the asynchronous component of your function may be terminated before it completes.

Event-driven functions

Implicit return

  exports.implicitlyReturning = async (event, context) => {
    return await asyncFunctionThatReturnsAPromise();
  };

Explicit return

  exports.explicitlyReturning = function (event, context) {
    return asyncFunctionThatReturnsAPromise();
  };

HTTP functions

// OK: await-ing a Promise before sending an HTTP response
await Promise.resolve();

// WRONG: HTTP functions should send an
// HTTP response instead of returning.
return Promise.resolve();

// HTTP functions should signal termination by returning an HTTP response.
// This should not be done until all background tasks are complete.
res.send(200);
res.end();

// WRONG: this may not execute since an
// HTTP response has already been sent.
return Promise.resolve();

Warning: failure to properly signal your function's termination may cause your function to either terminate early, or keep running until its timeout is reached.

Use middleware to handle HTTP requests

Node.js HTTP functions provide request and response objects that are compatible with ExpressJS to make consuming HTTP requests simpler. Cloud Run functions automatically reads the request body, so you will always receive the body of a request independent of the media type. This means that HTTP requests should be considered to have been fully read by the time your code is executed. The nesting of ExpressJS apps should be used with this caveat—specifically, middleware that expects the body of a request to be unread might not behave as expected.

Use ES Modules

ECMAScript modules (ES modules or ESM) are a TC39 standard, unflagged feature in Node version 14+ for loading JavaScript modules. Unlike CommonJS, ESM provides an asynchronous API for loading modules. It also provides a popular syntax improvement with import and export statements that can be used within a Cloud Run function (instead of require statements).

To use ESM within a Cloud Run function, you must declare "type": "module" within your package.json.

{
  ...
  "type": "module",
  ...
}

Then you can use import and export statements.

Learn more about using ES modules.