faas-js-runtime

FaaS Node.js Runtime Framework

This module provides a Node.js framework for executing a function that exists in a user provided directory path as an index.js file. The directory may also contain an optional package.json file which can be used to declare runtime dependencies for the function.

The function is loaded, and then invoked for incoming HTTP requests at localhost:8080. The incoming request may be a Cloud Event or just a simple HTTP GET request. In either case, the function will receive a Context object instance that has an event property. For a raw HTTP request, the incoming request is converted to a Cloud Event.

The invoked user function can be async but that is not required.

CLI

The easiest way to get started is to use the CLI. You can call it with the path to any JavaScript file which has a default export that is a function. For example,

// index.js
function handle(context) {
  const event = context.cloudevent;
  // business logic
  return {
    statusCode: 200,
    statusMessage: 'OK'
  }
}

module.exports = handle;

You can expose this function as an HTTP endpoint at localhost:8080 with the CLI.

npx faas-js-runtime ./index.js

Usage

In my current working directory, I have an index.js file like this.

const { start } = require('faas-js-runtime');
const options = {
  // Pino is used as the logger implementation. Supported log levels are
  // documented at this link:
  // https://github.com/pinojs/pino/blob/master/docs/api.md#options
  logLevel: 'info'
}

// My function directory is in ./function-dir
start(require(`${__dirname}/function-dir/`), server => {
  // The server is now listening on localhost:8080
  // and the function will be invoked for each HTTP
  // request to this endpoint.
  console.log('Server listening');

  // Whenever you want to shutdown the framework
  server.close();
}, options);

In ./function-dir, there is an index.js file that looks like this.

module.exports = async function myFunction(context) {
  const ret = 'This is a test function for Node.js FaaS. Success.';
  return new Promise((resolve, reject) => {
    setTimeout(_ => {
      context.log.info('sending response to client')
      resolve(ret);
    }, 500);
  });
};

You can use curl to POST to the endpoint:

$ curl -X POST -d 'hello=world' \
  -H'Content-type: application/x-www-form-urlencoded' http://localhost:8080

You can use curl to POST JSON data to the endpoint:

$ curl -X POST -d '{"hello": "world"}' \
  -H'Content-type: application/json' \
  http://localhost:8080

You can use curl to POST an event to the endpoint:

$ curl -X POST -d '{"hello": "world"}' \
  -H'Content-type: application/json' \
  -H'Ce-id: 1' \
  -H'Ce-source: cloud-event-example' \
  -H'Ce-type: dev.knative.example' \
  -H'Ce-specversion: 0.2' \
  http://localhost:8080

Sample

You can see this in action, executing the function at test/fixtures/async by running node hack/run.js.

Tests

Just run npm test.

Changelog

0.7.0 (2021-05-24)

Features

• add TypeScript type definitions (#90) (d43fa28)
• cli: pass --logLevel and --port from the cli or as env variables (d6b32a3)

Bug Fixes

• change index.js to not have a default export (#93) (d5bfd68)