Deploying Rails to Netlify

Published December 2019

You read that title right. www.danott.co is a Rails application deployed to Netlify. More specifically it’s a static site that is generated by Rails. Whenever I push to my git repo Netlify runs bin/rails build and a fresh site is deployed in under a minute.

Why

I recently migrated my site from Jekyll deployed on GitHub pages to Gatsby deployed on Netlify. The pain points of my Jekyll setup were all self induced. I had a clobbered together setup for managing JavaScript and stylesheets. I was trying to do some things that the system wasn’t built to do. I wanted first class support for modern front end tooling, and dynamic build time data.

As an example pain, the links page is driven by my Pinboard bookmarks. I wanted to be able to redeploy when I added a new bookmark. Gatsby’s build-time fetching of data sources paired with Netlify’s build hooks fit this need nicely.

I’d been rolling with this for a few months, but something felt off. Don’t get me wrong, I like Gatsby well enough. Working with React components that are hydrated by GraphQL is pretty cool. The hot reloading of every change is a developers dream. It’s the single-page-app by default that didn’t mesh with my values.

See, I came up in the time of progressive enhancement and “the semantic web”. While some in this community take these principles to a religious level that is not helpful, I do believe in the main sentiment. For my personal website, I want to be delivering static html, with a little bit of style and JavaScript sprinkled in.

Rails is really good and rendering html with a little bit of style and JavaScript sprinkled in. It’s also the hammer I’m most comfortable with, so I fully recognize I’m making my personal website look like a nail. 🔨

How

I’ve implemented a build script that is invoked with bin/rails build. This script is a composition of a few smaller steps.

  1. Grab remote content with my custom bin/rails import
  2. Compile assets with bin/rails webpacker:compile
  3. Generate static pages with bin/rails html:build

The idea for step one is inspired by Gatsby. I built a small class that hits the json endpoint and stores the data locally for filtering/rendering/etc.

Step two is standard fare for deploying a modern Rails application, static or otherwise.

Step three is where the magic happens. Reaching back into the history of Rails, you’ll discover the actionpack_page-caching gem. This gem writes the response body of a Rails controller action to a html file on the filesystem. This file can then be read by a server to avoid the Rails stack entirely. I still have a hard time imagining how this gem could be practical in most Rails applications, but it does exactly what I need for generating a static site.

So I built a tiny class called the Crawler. This class is responsible for keeping track of all the pages we want to generate. And then generating them. (Another Gatsby inspiration, mimicing the createPage API.)

class Crawler
  attr_reader :paths

  def initialize(paths: [])
    @paths = paths
  end

  def call
    Hash[paths.map { |path| visit(path) }]
  end

  def visit(path)
    env = Rack::MockRequest.env_for(path).merge("HTTP_HOST" => "www.danott.co")
    rack_response = Rails.application.call(env)
    [path, rack_response.first]
  end
end

# An oversimplification of the pages registered.
Crawler.new(paths: %w[/links /poetry, /posts]).call
# => { "/links" => 200, "/poetry" => 200, "/posts" => 200 }

I’m returning a hash of requested paths to response codes so I can test that my build script is working!

class CrawlerTest < Minitest::Test
  def test_smoke_test
    responses = Crawler.new(paths: all_the_paths).call
    assert responses.values.all? { |code| code == 200 }
  end
end

In development I have page caching turned off and the development experience is like any other Rails app. In production I have page caching turned on, and the crawler generates everything in the build step. In the immediate I’m very happy to have the trusty hammer of a majestic monolith powering my static site.