Deploying a Flask + Vue app to Heroku

In this post, I'll walk you through how to deploy a Flask and Vue app to Heroku. The final product is a super basic project you can extend to your needs.

Inspiration was drawn from this post by Shaylan Dias and has been adapted to Vue.

TLDR; Here's my GitHub Repo and here's the final product.

Step 1: Create a basic Vue app

We're using Vue CLI for this project.

mkdir heroku-test
cd heroku-test

# Instantiate git
git init

# Vue CLI to create child folder
vue create client

cd client
npm start

Now, you'll get a localhost link in your terminal. Visit that and view your frontend.

Step 2: Create Flask server

I assume you have pip installed for this. If not, download pip.

# Create a virtual Python environment for this project
python3 -m venv .venv

# Activate the virtual env
source .venv/bin/activate

# Install dependencies
pip install flask gunicorn python-dotenv

# Create requirements.txt
pip freeze > requirements.txt

# Set up the .env file
touch .env
echo "FLASK_APP=server.app:app" > .env

# Create the server
mkdir server
cd server
touch app.py

Now you have to set up app.py, this is a basic script that'll do the job:

from flask import Flask 
from dotenv import load_dotenv
import os
load_dotenv()

# Set up the app and point it to Vue
app = Flask(__name__, static_folder='../client/dist/',    static_url_path='/')

# Set up the index route
@app.route('/')
def index():
    return app.send_static_file('index.html')

if __name__ == "__main__":
    port = int(os.environ.get("PORT", 8000))
    app.run(host='0.0.0.0', port=port)

When setting upp the app (app=...) it's crucial that it's pointed to Vues static files. When using Vue CLI, these can be found in the dist folder.

Step 3: Setup for Heroku

First, create a package.jsonand Procfile in the root of your project.

The Procfile will tell Heroku what processes to run.

# Procfile
web: npm start

And package.json specifies the project's dependencies:

# package.json
{
  "name": "heroku-flask-vue",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "core-js": "^3.6.5",
    "eslint": "^7.13.0",
    "vue": "^2.6.11"
  },
  "devDependencies": {
    "@vue/cli-plugin-babel": "~4.5.0",
    "@vue/cli-plugin-eslint": "~4.5.0",
    "@vue/cli-service": "~4.5.0",
    "babel-eslint": "^10.1.0",
    "eslint": "^6.7.2",
    "eslint-plugin-vue": "^6.2.2",
    "vue-template-compiler": "^2.6.11"
  },
  "scripts": {
    "start": "gunicorn server.app:app",
    "build": "cd client && npm run build"
  },
  "eslintConfig": {
    "extends": "plugin:vue/recommended"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "engines": {
    "node": "12.x"
  }
}

Step 4: Create the Heroku app

Now, we have to create a Heroku app. If you don't have Heroku CLI installed, follow these instructions.

heroku create <name-for-your-app>

# create a remote git connection
heroku git:remote -a <name-for-your-app>

# These buildpack tell Heroku to install Python and Node
heroku buildpacks:add --index 1 heroku/nodejs
heroku buildpacks:add --index 2 heroku/python

Step 5: Test locally and then deploy

npm run build
npm start

# If it works, deploy!
git commit -am 'Ready to deploy!'
git push heroku master

Heroku CLI will give you a link when your app has been deployed, follow that and voilá!

Final

Great job! You've created a Vue + Flask app and deployed it to Heroku. Now try changing for example the <h1>. PS. Don't forget to run npm run build before pushing to Heroku again.