Overview
The Node.js runtime is the software stack responsible for installing your application code and dependencies, and then running that application in the flexible environment.
Important: Starting with Node.js 18, runtimes will be using newer and secure operating systems such as Ubuntu 22.
Preview: Starting with version
18
, new Node.js runtimes are built using buildpacks which enables you to choose an operating system. To use these new runtimes, you must specify additional settings in yourapp.yaml
. Learn more.Node.js runtimes version
17
and earlier are built using Docker. The Node.js17
and earlier runtimes are based on Ubuntu 16.04, and the source code for the Node.js runtime is publicly available on GitHub.
Package manager
During deployment, the runtime uses either the npm or yarn package manager to install dependencies and start the application. The package manager is set with the following logic:
- The default package manager is
npm
. - If a
yarn.lock
file is present in your application's root directory, the runtime instead uses theyarn
package manager. - If both a
package-lock.json
andyarn.lock
exist, your deployment will fail with an error. If you need both files, you can add one of them to theskip_files
section of yourapp.yaml
file to resolve which package manager to use.
Choose a Node.js version
New runtime versions (Preview)
For Node.js runtime version 18 and later you must include the runtime_config
and operating_system
settings in your
app.yaml
to specify an operating system.
Node.js version 18 (preview) runs on Ubuntu 22.
Your application must use a gcloud
CLI version 420.0.0 or later.
To view the current gcloud
version, run the gcloud version
command.
Optional: You can specify a runtime version by including the runtime_version
setting in your app.yaml
. By default, the latest Node.js version is used if the runtime_version
setting is not specified.
You can also specify a different Node.js version in your application's package.json
file by using the engines
field.
Note that when you use the engines
field to specify a version, the runtime_version
setting takes precedence.
To prevent unexpected breakages, you should specify a Node.js version.
Examples
Specifying Node.js 18 version on Ubuntu 22 via
runtime_version
:runtime: nodejs env: flex runtime_config: operating_system: "ubuntu22" runtime_version: 18
Specifying the latest supported Node.js version on Ubuntu 22:
runtime: nodejs env: flex runtime_config: operating_system: "ubuntu22"
Specifying a Node.js version in your application's package.json file by using the engines field.
{ "engines": { "node": "18.x" } }
The
engines.node
property can be a semver range. If you specify this, the runtime downloads and installs the latest version of Node.js that matches the semver range. If no match is found, the application will fail to deploy and the runtime will return an error message.
Previous runtime versions
The default Node.js engine aims to be the latest LTS release. You can
specify a different Node.js version in your application's package.json
file by using the engines
field. To prevent unexpected breakages,
you should specify a Node.js version.
The following example configures the runtime to use the latest Node 9 release.
{
"engines": {
"node": "9.x"
}
}
The engines.node
property can be a semver range. If you specify
this, the runtime downloads and installs the latest version of Node.js that
matches the semver range. If no match is found, the application will fail to
deploy and the runtime will return an error message.
Package manager version
The runtime image aims to use the latest yarn
release and the release of
npm
that is available in the latest Node.js LTS release.
You can specify a different package manager version to use in your application's
package.json
file by using the engines
field. In this
case, the runtime will ensure that the package manager used for the deployment
has a version that matches the specification listed in the
engines
field.
If both a yarn
and npm
version specification is
given, only the package manager that is used for the deployment will be
updated if needed. This saves deployment time by not installing a custom
version of a package manager if it is not actually being used to deploy your
application.
The following example configures the runtime to use a custom version of npm
:
{
"engines": {
"npm": "5.x"
}
}
The next example configures the runtime to use a custom version of yarn
:
{
"engines": {
"yarn": ">=1.0.0 <2.0.0"
}
}
The engines.npm
and engines.yarn
properties can both be a
semver range.
Dependencies
During deployment, the runtime will use either the npm or yarn
package manager to install dependencies by running npm install
or
yarn install
. See the Package Manager section for more
information on how the runtime selects the package manager to use.
Also, for more information about managing Node.js packages on Google App Engine, see Using Node.js Libraries.
To enable the use of Node.js packages that require native extensions, the following Ubuntu packages are pre-installed in the Docker image.
If your application requires additional operating-system-level dependencies, you will need to use a custom runtime based on this runtime to install the appropriate packages.
Application startup
The runtime starts your application by using npm start
, which uses
the command specified in package.json
. For example:
"scripts": {
"start": "node app.js"
}
Your start script should start a web server that responds to HTTP requests on
the port specified by the PORT
environment variable, typically 8080.
Extending the runtime
You can use custom runtimes to add
additional functionality to a Node.js app running in the App Engine flexible environment. To configure
a custom runtime, replace the following line in your app.yaml
file:
runtime: nodejs
with this line:
runtime: custom
You must also add Dockerfile
and .dockerignore
files in the same directory
that contains the app.yaml
file.
Visit the Custom runtimes documentation to learn how to define a Dockerfile in a custom runtime.
HTTPS and forwarding proxies
App Engine terminates the HTTPS connection at the load balancer and forwards the
request to your application. Some applications need to determine the original
request IP and protocol. The user's IP address is available in the standard
X-Forwarded-For
header. Applications that require this information should
configure their web framework to trust the proxy.
With Express.js, use the trust proxy
setting:
app.set('trust proxy', true);
For information on enforcing HTTPS connections, see How Requests are Handled.
Environment variables
The following environment variables are set by the runtime environment:
Environment variable | Description |
---|---|
GAE_INSTANCE |
The name of the current instance. |
GAE_MEMORY_MB |
The amount of memory available to the application process. |
GAE_SERVICE |
The service name specified in your application's app.yaml
file, or if no service name is specified, it is set to
default .
|
GAE_VERSION |
The version label of the current application. |
GOOGLE_CLOUD_PROJECT |
The Project ID associated with your application, which is visible in the Google Cloud console |
NODE_ENV |
When your app is deployed, the value is production . |
PORT |
The port that will receive HTTP requests. Set to 8080 .
|
You can set additional environment variables with
app.yaml
.
Metadata server
Each instance of your application can use the Compute Engine metadata server to query information about the instance, including its host name, external IP address, instance ID, custom metadata, and service account information. App Engine does not allow you to set custom metadata for each instance, but you can set project-wide custom metadata and read it from your App Engine and Compute Engine instances.
This example function uses the metadata server to get the external IP address of the instance: