Run a Node App

Getting an application running on Fly.io is essentially working out how to package it as a deployable image. Once packaged it can be deployed to the Fly.io global application platform.

In this guide we'll learn how to deploy a Node application on Fly.io.

The Hellonode Application

Our example will be a basic "hello world" example using Node and Express.

You can get the code for the example from the hellonode GitHub repository. Just git clone https://github.com/fly-apps/hellonode-builtin to get a local copy. Here's all the code:

const express = require("express");
const app = express();
const port = process.env.PORT || 3000;

app.get(["/", "/:name"], (req, res) => {
  greeting = "<h1>Hello From Node on Fly!</h1>";
  name = req.params["name"];
  if (name) {
    res.send(greeting + "</br>and hello to " + name);
  } else {
    res.send(greeting);
  }
});

app.listen(port, () => console.log(`HelloNode app listening on port ${port}!`));

We'll call this file server.js and run npm init and npm install express --save so we've got the basic node setup.

Running the Application

Run node server.js to start the application

node server.js

HelloNode app listening on port 3000!

And connect to localhost:3000 to confirm that you have a working Node application. Now to package it up for Fly.

We are ready to start working with Fly and that means we need flyctl, our CLI app for managing apps on Fly. If you've already installed it, carry on. If not, hop over to our installation guide. Once thats installed you'll want to log in to Fly.

Launch the App on Fly

To launch an app on fly, run flyctl launch in the directory with your source code. This will create and configure a fly app for you by inspecting your source code, then prompt you to deploy.

flyctl launch

Scanning source code
Detected NodeJS app
Using the following build configuration
        Builder: heroku/buildpacks:20
? Select organization: Demo (demo)
? Select region: ord (Chicago, Illinois (US))
? Would you like to deploy now? Yes

Deploying hellonode
...

First, this command scans your source code to determine how to build a deployment image as well as identify any other configuration your app needs, such as secrets and exposed ports.

After your source code is scanned and the results are printed, you'll be prompted for an organization. Organizations are a way of sharing applications and resources between Fly users. Every fly account has a personal organization, called personal, which is only visible to your account. Let's select that for this guide.

Next, you'll be prompted to select a region to deploy in. The closest region to you is selected by default. You can use this or change to another region.

At this point, flyctl creates an app for you and writes your configuration to a fly.toml file. You'll then be prompted to build and deploy your app. Once complete, your app will be running on fly.

Inside `fly.toml`

The fly.toml file now contains a default configuration for deploying your app. In the process of creating that file, flyctl has also created a Fly-side application slot of the same name, "hellonode". If we look at the fly.toml file we can see the name in there:

app = "hellonode"

[build]
  builder = "heroku/buildpacks:20"

[[services]]
  internal_port = 8080
  protocol = "tcp"

...

The flyctl command will always refer to this file in the current directory if it exists, specifically for the app name/value at the start. That name will be used to identify the application to the Fly platform. The rest of the file contains settings to be applied to the application when it deploys.

We'll have more details about these properties as we progress, but for now, it's enough to say that they mostly configure which ports the application will be visible on.

Deploying to Fly

To deploy changes to your app, just run:

flyctl deploy

This will lookup our fly.toml file, and get the app name hellonode from there. Then flyctl will start the process of deploying our application to the Fly platform. Flyctl will return you to the command line when it's done.

Viewing the Deployed App

Now the application has been deployed, let's find out more about its deployment. The command flyctl info will give you all the essential details.

flyctl status

App
  Name     = hellonode
  Owner    = dj
  Version  = 0
  Status   = running
  Hostname = hellonode.fly.dev

Allocations
ID       VERSION REGION DESIRED STATUS  HEALTH CHECKS      RESTARTS CREATED
ada41989 0       fra    run     running 1 total, 1 passing 0        33s ago

Connecting to the App

The quickest way to browse your newly deployed application is with the flyctl open command.

flyctl open

Opening http://hellonode.fly.dev/

Your browser will be sent to the displayed URL. Fly will auto-upgrade this URL to an HTTPS secured URL.

Bonus Points

When our Dockerfile is run, it copies everything from the directory over to the Docker image. For Node applications, some directories like node_modules are going to be rebuilt anyway so there's no need to copy them. Create a .dockerignore file and add node_modules to it to do this.
You can also use the .dockerignore to skip unused project assets and any other files which aren't needed at runtime.
If you want to know what IP addresses the app is using, try flyctl ips list:

flyctl ips list

TYPE ADDRESS                              CREATED AT
v4   50.31.246.73                         23m42s ago
v6   2a09:8280:1:3949:7ac8:fe55:d8ad:6b6f 23m42s ago

Arrived at Destination

You have successfully built, deployed, and connected to your first Node application on Fly.

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