Active Record

In this guide we’ll develop and deploy a Rails application that scaffolds a database table.

Create an application

Start by verifying that you have Rails installed, and then by creating a new application:

$ rails --version
$ rails new list --database postgresql
$ cd list

Scaffold to Success

Real Rails applications store data in databases, and Rails scaffolding makes it easy to get started. We are going to start with the simplest table possible, add a small bit of CSS to make the display a bit less ugly, and finally adjust our routes so that the main page is the index page for our new table.

Scaffold and style a list of names

Since we are focusing on fly deployment rather than Rails features, we will keep it simple and create a single table with exactly one column:

bin/rails generate scaffold Name name

Now add the following to the bottom of app/assets/stylesheets/application.css:

#names {
  display: grid;
  grid-template-columns: 1fr max-content;
  margin: 1em;
}

#names strong {
  display: none;
}

#names p {
  margin: 0.2em;
}

And finally, as the splash screen served it purpose, edit config/routes.rb, and connect the root with the names index:

 Rails.application.routes.draw do
   # Define your application routes per the DSL in https://guides.rubyonrails.org/routing.html

   # Defines the root path route ("/")
-  root "rails/welcome#index"
+  root "names#index"
 end

While certainly not fancy or extensive, we now have an application that makes use of a database.

Let’s deploy it.

Launch

To configure and launch the app, you can use fly launch and follow the wizard. Fly.io will automatically detect that Postgres is required by your application.

fly launch

Detected a Rails app
Creating app in ~/tmp/list
We're about to launch your Rails app on Fly.io. Here's what you're getting:

Organization: Joe Developer                                             (fly launch defaults to the personal org)
Name:         list-little-fire-1088                                     (generated)
Region:       Ashburn, Virginia (US)                                    (this is the fastest region for you)
App Machines: shared-cpu-1x, 1GB RAM                                    (most apps need about 1GB of RAM)
Postgres:     (Fly Postgres) 1 Node, shared-cpu-1x, 256MB RAM, 1GB disk (determined from app source)
Redis:        <none>                                                    (not requested)
Tigris:       <none>                                                    (not requested)

? Do you want to tweak these settings before proceeding? (y/N) 

For demo purposes you can accept the defaults. You can always change these later. So respond with “N” (or simply press enter).

This will take a few seconds as it uploads your application, builds a machine image, deploys the images, and then monitors to ensure it starts successfully. Once complete visit your app with the following command:

fly apps open

That’s it! You are up and running! Wasn’t that easy?