Functions Framework for Node.js

An open source FaaS (Function as a service) framework for writing portable Node.js functions -- brought to you by the Google Cloud Functions team.

The Functions Framework lets you write lightweight functions that run in many different environments, including:

• Google Cloud Functions
• Your local development machine
• Cloud Run and Cloud Run on GKE
• Knative-based environments

The framework allows you to go from:

exports.helloWorld = (req, res) => {
  res.send('Hello, World');
};

To:

curl http://my-url
# Output: Hello, World

All without needing to worry about writing an HTTP server or complicated request handling logic.

Features

• Spin up a local development server for quick testing
• Invoke a function in response to a request
• Automatically unmarshal events conforming to the CloudEvents spec
• Portable between serverless platforms

Installation

Add the Functions Framework to your package.json file using npm.

npm install @google-cloud/functions-framework

Quickstart: Hello, World on your local machine

Create an index.js file with the following contents:

exports.helloWorld = (req, res) => {
  res.send('Hello, World');
};

Run the following command:

npx @google-cloud/functions-framework --target=helloWorld

Open http://localhost:8080/ in your browser and see Hello, World.

Quickstart: Set up a new project

Create an index.js file with the following contents:

exports.helloWorld = (req, res) => {
  res.send('Hello, World');
};

To run a function locally, first create a package.json file using npm init:

npm init

Now install the Functions Framework:

npm install @google-cloud/functions-framework

Add a start script to package.json, with configuration passed via command-line arguments:

  "scripts": {
    "start": "functions-framework --target=helloWorld"
  }

Use npm start to start the built-in local development server:

npm start
...
Serving function...
Function: helloWorld
URL: http://localhost:8080/

Send requests to this function using curl from another terminal window:

curl localhost:8080
# Output: Hello, World

Optional: containerize your function

To run your function in a container, create a Dockerfile with the following contents:

# Use the official Node.js 10 image.
# https://hub.docker.com/_/node
FROM node:10

# Create and change to the app directory.
WORKDIR /usr/src/app

# Copy application dependency manifests to the container image.
# A wildcard is used to ensure both package.json AND package-lock.json are copied.
# Copying this separately prevents re-running npm install on every code change.
COPY package.json package*.json ./

# Install production dependencies.
RUN npm install --only=production

# Copy local code to the container image.
COPY . .

# Run the web service on container startup.
CMD [ "npm", "start" ]

Start the container locally by running docker build and docker run:

docker build -t helloworld . && docker run -p 8080:8080 -it helloworld

Send requests to this function using curl from another terminal window:

curl localhost:8080
# Output: Hello, World

Run your function on serverless platforms

Google Cloud Functions

The Node.js 10 runtime on Google Cloud Functions is based on the Functions Framework. On Cloud Functions, the Functions Framework is completely optional: if you don't add it to your package.json, it will be installed automatically.

After you've written your function, you can simply deploy it from your local machine using the gcloud command-line tool. Check out the Cloud Functions quickstart.

gcloud functions deploy helloworld --runtime nodejs8 --trigger-http

Cloud Run/Cloud Run on GKE

You can deploy your containerized function to Cloud Run or any Knative-based environment. Check out the Cloud Run quickstart.

docker build -t gcr.io/$GOOGLE_CLOUD_PROJECT/helloworld .
docker push gcr.io/$GOOGLE_CLOUD_PROJECT/helloworld
gcloud beta run deploy helloworld --image gcr.io/$GOOGLE_CLOUD_PROJECT/helloworld --region us-central1

If you want even more control over the environment, you can deploy your container image to Cloud Run on GKE. With Cloud Run on GKE, you can run your function on a GKE cluster, which gives you additional control over the environment (including use of GPU-based instances, longer timeouts and more).

Create a GKE cluster with Cloud Run enabled (see docs above) and deploy the same container with gcloud:

gcloud beta run deploy helloworld --image gcr.io/$GOOGLE_CLOUD_PROJECT/helloworld --cluster cloud-run-on-gke --cluster-location us-central1-a

Container environments based on Knative

Cloud Run and Cloud Run on GKE both implement the Knative Serving API. The Functions Framework is designed to be compatible with Knative environments. Just build and deploy your container to a Knative environment.

Configure the Functions Framework

You can configure the Functions Framework using command-line flags or environment variables. If you specify both, the environment variable will be ignored.

Command-line flag	Environment variable	Description
--port	PORT	The port on which the Functions Framework listens for requests. Default: 8080
--target	FUNCTION_TARGET	The name of the exported function to be invoked in response to requests. Default: function
--signature-type	FUNCTION_SIGNATURE_TYPE	The signature used when writing your function. Controls unmarshalling rules and determines which arguments are used to invoke your function. Default: http; accepted values: http or event

You can set command-line flags in your package.json via the start script. For example:

  "scripts": {
    "start": "functions-framework --target=helloWorld"
  }

Enable CloudEvents

The Functions Framework can unmarshall incoming CloudEvents payloads to data and context objects. These will be passed as arguments to your function when it receives a request. Note that your function must use the event-style function signature:

exports.helloEvents = (data, context) => {
  console.log(data);
  console.log(context);
};

To enable automatic unmarshalling, set the function signature type to event using a command-line flag or an environment variable. By default, the HTTP signature will be used and automatic event unmarshalling will be disabled.

For more details on this signature type, check out the Google Cloud Functions documentation on background functions.

Contributing

Contributions to this library are welcome and encouraged. See CONTRIBUTING for more information on how to get started.