FLAME for JavaScript: Run a function on another Machine

This is a simple example app demonstrating how to run a particular function on a temporary copy of your app, using the FLAME pattern. Checkout the blog post that explains this code in more detail: https://fly.io/javascript-journal/flame-for-javascript-rethinking-serverless

FLAME (Fleeting Lambda Application for Modular Execution), which was first introduced by Chris McCord, creator of the Phoenix framework, was originally demo'ed in an Elixir library. This app is a case study on how it can be implemented in vanilla JavaScript. FLAME is a new way to horizontally auto-scale your application code in a more modular way. You can read more about it in Chris's post here: https://fly.io/blog/rethinking-serverless-with-flame/

Prerequisites

While FLAME is a cloud-provider-agnostic pattern, this project uses Fly.io's Machines API to auto-scale your code. As such, your app will need a Fly token to be able to spawn new machines.

If you already have the flyctl CLI installed, you can run the following to obtain a new token:

$ flyctl auth token [flags]

Deploying this demo

First launch this app.

$ fly launch --copy-config --no-public-ips --no-deploy

Creating app in /Users/lubien/workspace/run-this-on-another-machine
Scanning source code
Detected a Dockerfile app
? Choose an app name (leave blank to generate one): another-machines
? Select Organization: Lubien (personal)
? Choose a region for deployment: Sao Paulo, Brazil (gru)
App will use 'gru' region as primary

The let's set the deploy token

$ fly secrets set FLY_API_TOKEN=$(fly auth token)
Secrets are staged for the first deployment

Make your first deployment and remember the machine ID.

$ fly deploy

...
Watch your app at https://fly.io/apps/another-machines/monitoring

Updating existing machines in 'another-machines' with rolling strategy
  Machine 3287114c3d7085 [app] has state: started
  [1/1] Checking that 3287114c3d7085 [app] is up and running
  Finished deploying

SSH into the main machine and run node /app/index.mjs

$ fly ssh console -s
? Select VM: gru: 3287114c3d7085 fdaa:0:3335:a7b:1f60:1b01:ce26:2 muddy-violet-4491
Connecting to fdaa:0:3335:a7b:1f60:1b01:ce26:2... complete

root@3287114c3d7085:/app# node /app/index.mjs 

If you look into your app Monitoring page, there will be a new machine.

Next steps:

• Stop machines after they're done
• Reuse stopped machines
• Pool machines?