Node.js Builder (@now/node)

The @now/node Builder takes an entrypoint of a Node.js function, builds its dependencies (if any) and bundles them into a Lambda.

When to Use It

This Builder is the recommended way to introduce any Node.js-based dynamic request handling into your codebases.

It can be used directly (as a single file, like my-function.js), or you can define an index.js file inside a directory.

How to Use It

For this example, we will create a hello endpoint that we want to access as my-deployment.url/api/hello.

Let's create our project structure:

Inside my-node-project > api > hello we will create an index.js file.

The index.js file exports a Node.js function that takes in the standard Node.js request and response objects:

module.exports = (req, res) => {
  const { name = 'World' } = req.query
  res.send(`Hello ${name}!`)
}

An example serverless Node.js function.

The only step left is to define a build that will take this directory's entrypoint (index.js), build it and turn it into a lambda:

{
  "version": 2,
  "builds": [{ "src": "api/hello/index.js", "use": "@now/node" }]
}

An example now.json configuration using the @now/node builder.

Our resulting deployment is here: https://my-node-project-5gkn6kqfy.now.sh/

The example deployment above is open-source and you can view the code for it here: https://my-node-project-5gkn6kqfy.now.sh/_src

You can pass query parameters to make the name change:

The lambda using the name query parameter to change the text using Node.js.

Request and Response Objects

For each invocation of a Node.js lambda, two objects, request and response, are passed to the function. These objects are the standard HTTP request and response objects given and used by Node.js.

Helpers

In addition to the standard Node.js request and response methods, we provide a set of helper properties and methods to make it even easier for you to build a new lambda function:

The following lambda example showcases the use of req.query, req.cookies and req.body helpers:

module.exports = (req, res) => {
  let who = 'anonymous'

  if (req.body && req.body.who) {
    who = req.body.who
  } else if (req.query.who) {
    who = req.query.who
  } else if (req.cookies.who) {
    who = req.cookies.who
  }

  res.status(200).send(`hi ${who}, what's up?`)
}

Example Node.js lambda using the req.query, req.cookies and req.body helpers. It returns greetings for the user specified using req.send().

{
  "builds": [
    { "src": "my-file.js", "use": "@now/node", "config": { "helpers": "false" } }
  ]
}

req.body

We populate the req.body property on the request object with a parsed version of the content sent with the request when it is possible.

We follow a set of rules on the Content-type header sent by the request to do so:

With the req.body helper, you can build applications without extra dependencies or having to parse the content of the request manually. The following example inspects req.body, if it is 'ping', it will return 'pong'.

module.exports = (req, res) => {
  if (typeof req.body !== 'string') {
    return res.status(400).text('Invalid request')
  }

  if (req.body !== 'ping') {
    return res.status(400).text('The value expected is `ping`')
  }

  res.status(200).send('pong')
}

An example Node.js lambda using the req.body helper that returns pong when you send ping.

Typescript support

We provide types for the request and response objects.

To install these types, use the following command:

yarn add @now/node --dev

Or, if you're using npm:

npm install @now/node --save-dev

Once the types have been installed, import NowRequest and NowResponse from @now/node, to type the request and response objects:

import { NowRequest, NowResponse } from '@now/node'

export default function(req: NowRequest, res: NowResponse) {
  const { name = 'World' } = req.query
  res.send(`Hello ${name}!`)
}

An example "Hello World" Typescript lambda using the req.query helper.

Async support

We support asynchronous functions out-of-the-box.

In this example, we use the package asciify-image to create ascii art from a person's avatar on github. First, we need to install the package:

yarn add asciify-image

In our code, we export an asynchronous function and we take advantage of the helpers.

const asciify = require('asciify-image')

module.exports = async (req, res) => {
  if (!req.query.username) {
    return res.status(400).send('username is missing from query parameters')
  }

  const avatarUrl = `https://github.com/${req.query.username}.png`

  const opts = { fit: 'box', width: 40, height: 40 }
  const asciified = await asciify(avatarUrl, opts)

  return res.status(200).send(asciified)
}

An example showcasing the use of an asynchronous function.

Deploying with Static Content

You can upload static content alongside your Node.js application by using the @now/static Builder.

For example, if you have a /static directory and an index.js like the one from the example above, you can serve that directory statically by extending your now.json configuration:

{
  "version": 2,
  "builds": [
    { "src": "api/hello/index.js", "use": "@now/node" },
    { "src": "static/**", "use": "@now/static" }
  ]
}

Deploying a serverless Node.js function along with static files.

For more information on including static files in your project, read the documentation for @now/static:

Technical Details

Entrypoint

The entrypoint of this Builder is always a JavaScript file that exposes a function. If you want to expose a server, you should read the documentation for the @now/node-server Builder, although this is not recommended.

Dependencies Installation

The installation algorithm of dependencies works as follows:

• If a package-lock.json is present, npm install is used
• Otherwise, yarn is used.

Private npm modules

To install private npm modules, define NPM_TOKEN as a build environment variable in now.json.

Build Step

You can run build tasks by creating a now-build script within a package.json file at the entrypoint's level or higher.

{
  "scripts": {
    "now-build": "node ./build.js"
  }
}

const fs = require('fs');
  fs.writeFile(
  'built-time.js',
  `module.exports = "${new Date()}"`,
  (err) => {
    if (err) throw err
    console.log('Build time file created successfully!')
  }
)

const BuiltTime = require('./built-time')

module.exports = (req, res) => {
  res.setHeader('content-type', 'text/plain');
  res.send(`
    This Lambda was built at ${new Date(BuiltTime)}.
    The current time is ${new Date()}
  `)
}

{
  "version": 2,
  "builds": [
    { "src": "index.js", "use": "@now/node" }
  ]
}

Node.js Version

The Node.js version used is the v8.10.

Maximum Lambda Bundle Size

To help keep cold boot times low, the maximum output bundle size for a Node.js output lambda is, by default, 5mb. This limit is extendable up to 50mb.

{
  "builds": [
    { "src": "*.js", "use": "@now/node", "config": { "maxLambdaSize": "10mb" } }
  ]
}