Elle Hallal 👩🏽‍💻

Posted on Sep 1, 2020 • Originally published at ellehallal.dev on Jan 30, 2019

How To Deploy A Web App To Heroku

#heroku #javascript #node #webpack

Originally posted at ellehallal.dev👩🏽‍💻

This is a quick blog on how I deployed my weather manager app to Heroku.

Deploying took longer than anticipated, due to an issue I was experiencing with dotenv-webpack and dotenv in a production environment. The following error kept popping up when deploying to Heroku:

failed to load ./.env

Thanks to one of my mentors, Dan, for helping me to figure out what was going on! As this issue has been resolved, this blog will outline the steps in an order that should not cause errors when deploying.

For reference, here’s how my weather manager files are organised. There are hidden files:

./dist contains main.js
.env (which contains my API key) is in the root directory

Step 1: Express.js — web app framework

Create server.js in the root directory, and add the following code:

const express = require("express");
const path = require("path");
const port = process.env.PORT || 8080;
const app = express();

app.use(express.static(__dirname + '/dist'));

app.get('*', (req, res) => {
  res.sendFile(path.resolve(__dirname, 'index.html'));
});

app.listen(port);

Run npm install express

Key points

__dirname is the directory where server.js is
__dirname + ‘/dist' is the current directory from where main.js is running

Step 2: Create webpack.prod.js

This step is important if you have dotenv-webpack installed. If installed then in webpack.config.js, dotenv-webpack is required:

const path = require("path");
const Dotenv = require("dotenv-webpack");

module.exports = {
  entry: "./src/index.js",
  mode: "development",
  output: {
    filename: "main.js",
    path: path.resolve(__dirname, "dist"),
  },
  node: {
    fs: "empty",
  },
  plugins: [new Dotenv()],
};

This is fine for development, but doesn’t seem to work well for production. Therefore, a similar file is needed for production only, which doesn’t contain references to dotenv-webpack.

Create a copy of webpack.config.js in your root directory and name it webpack.prod.js
In webpack.prod.js, remove references to dotenv-webpack, and replace it with the following:

const path = require("path");
const webpack = require("webpack");

module.exports = {
  entry: "./src/index.js",
  mode: "production",
  output: {
    filename: "main.js",
    path: path.resolve(__dirname, "dist"),
  },
  node: {
    fs: "empty",
  },
  plugins: [
    new webpack.DefinePlugin({
      "process.env": {},
    }),
  ],
};

Under scripts in package.json, add:

"scripts": {
  "start": "node server.js",
  "heroku-postbuild": "webpack --config webpack.prod.js"
},

As a result, Heroku will use the webpack.prod.js file, rather than the webpack.config.js file.

Set the version of npm and Node.js by adding the below to package.json:

"engines": {
  "node": "11.6.0",
  "npm": "6.5.0"
}

Step 3: Only require dotenv when NODE_ENV is set to development

Assuming dotenv is also installed, add the following to server.js, just under const app = express();

if (process.env.NODE_ENV == 'development')
require('dotenv').config({ silent: true });

Step 4: Set dotenv-webpack and dotenv as devDependencies

For dotenv-webpack and dotenv to be required during development only, run the following:

npm install dotenv --save-dev
npm install dotenv-webpack --save-dev

Step 5: Deploying to Heroku

Sign up to Heroku
Install Heroku CLI
Log into Heroku via the terminal with heroku login
Run heroku create to create your app on Heroku. An app name will be generated
Reinitialise the project by running git init
Set a Heroku remote branch by heroku git:remote --app [your-heroku-app-name]
Set your environment variables — or config vars as they’re referred to in Heroku. Here’s how I set my API key for openweathermap: heroku config:set API_KEY=myapikey3902e92e802e8
Git add and commit
Push to Heroku with git push heroku master

And that’s it (hopefully)!

DEV Community