Heroku from Scratch

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ℹ️ This post is for an internal workshop at the Financial Times.

We’re going to put togther a Heroku application, from scratch.

We’ll use the Heroku CLI, Node.js, Yarn (😱), and the express web framework.

And we’ll begin by building a basic hello world application using Express, we can then prepare the code for deployment to Heroku, and finally create the app in Heroku and ship it ⛴.

Making the application

If you don’t have Yarn already, check out their install page (basically brew install yarn).

First we’ll make a folder and generate our package.json to kick start the project.

mkdir hello-world
cd hello-world
git init
yarn init --yes --private

You should now have a package.json, with not much in it.

We can then add Express as a dependency.

yarn add express

Which updates our package.json, and creates node_modules/ and yarn.lock.

We should add node_modules/ to the list of ignored files for git.

GitHub maintain a brillant repository of .gitignore files sorted by programming language, so let’s borrow the one for Node.js.

Copy and paste the contents of Node.gitignore into a local file called .gitignore.

Now to write our application!

Add the following to a new file called app.js. This is just copy and pasted from https://expressjs.com/en/starter/hello-world.html.

const express = require("express");
const app = express();
const port = 3000;

app.get("/", (req, res) => res.send("Hello World!"));

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

We’ll also add a new scripts section to our package.json file, so that we can use yarn start to make developing locally easier.

Add the following to package.json.

"scripts": {
  "start": "node app.js"
}

Time to take it for a spin, run yarn start and you should see something like the following.

yarn run v1.9.4
$ node app.js
Example app listening on port 3000!

Open up http://localhost:3000 to see if it worked.

Let’s also add support for compression of our responses.

Express has a handy guide to run through.

First we need another dependency, compression.

yarn add compression

Then all we need to do is register the middleware in app.js and we’re done.

Make the following changes to app.js.

 const express = require("express");
+const compression = require("compression");
 
 const app = express();
 const port = 3000;
 
+app.use(compression());
+
 app.get("/", (req, res) => res.send("Hello World!"));
 
 app.listen(port, () => console.log(`Example app listening on port ${port}!`));

Then test it again with yarn start and opening http://localhost:3000.

Preparing it for Heroku

If you haven’t got it already, please install the Heroku CLI (again probabily brew install heroku/brew/heroku).

While we’ve got something working locally, there’s a few things we’ll need to change to make sure Heroku can run it too.

For this section we’ll follow the well documented guide published by Heroku, Preparing a Codebase for Heroku Deployment.

After this workshop, it’s also well worth checking out the Heroku guide on the Node.js best pratices for running on the platform.

Once we’re all done, we should then save our work in a commit.

git add .
git commit -m 'Initial commit 🚀.'

Creating the Heroku app

We’re going to use the CLI to do all this 😱.

First things first, we need to login!

heroku login --sso

Then we want to make a new app in Heroku.

heroku create

This will add a new remote to your git configuration for the project, called heroku.

You’ll also get a URL (like I got https://infinite-eyrie-31643.herokuapp.com/), this is where our application will run.

And that’s all it takes…

There are other things we could do, like renaming the application, and putting it in a better team, but we won’t bother about that for now.

Deploying 🚀

There’s a few ways of deploying to Heroku, we’re going to deploy to Heroku directly, using git.

Given we’ve already committed our code, and created the Heroku app, the only thing we need to do is use git to push our code to Heroku.

git push heroku master

We’ll then see the build logs as Heroku prepares our application for deployment.

To double check everything is running, run heroku ps to ensure that we have a web process running.

Finally, let’s actually check our app is on the internet.

heroku open

And that’s all there is to it 🎉.

Go ahead, make some changes to app.js and push them to Heroku!