Deploy flask app to Heroku

Flask is a micro web framework written in Python, released in April 2010, and is developed by Armin Ronacher. Heroku is a cloud platform that allows developers to deploy their apps online free of cost. This article contains step-by-step instructions to walk you through deploying your flask app to Heroku.

 

 

 

 

 

1. Prerequisites

 

The basic requirements for getting started with the deployment is:

 

- Installing Python

 

- Installing Git (Best for Source Code & Version Control Management)

 

- Signup for an account of Heroku:

 

 

 

You can create an account on Heroku by referring to the https://signup.heroku.com/ link.

 

 

 

 

2. Installing Heroku CLI

 

You can configure almost everything from Heroku GUI but It's preferred to install Heroku CLI since it is highly flexible.

 

If you are using macOS, install Heroku via brew.

 

 

 

brew tap heroku/brew && brew install heroku

 

 

 

For Linux, you can install it by executing the below command.

 

 

 

curl https://cli-assets.heroku.com/install.sh | sh

 

 

 

You can refer to the below guide for more information on the Installation of Heroku CLI.

 

 

 

Installing Heroku CLI - macOS, Windows, and Linux

 

 

 

3. Creating Flask application

 

 

 

Let's create a minimal flask application following the below steps.

 

 

 

Create Flask Working Directory

 

Create a directory of flask:

 

 

 

mkdir <app_name>

 

cd <app_name>

 

 

 

Creating a Virtual Environment

 

 

 

You can create a python virtual environment by executing the below command.

 

 

 

python -m venv venv

 

 

 

If you are on Linux/Mac you can execute the below command for activating your virtual environment.

 

 

 

source /venv/bin/activate

 

 

 

For Windows, you can execute the below command:

 

 

 

venvScriptsactivate.bat

 

 

 

 

 

 

Installing flask, requests, and Gunicorn

 

 

 

Since we have created a virtual environment, now we will proceed ahead with the installation of the flask package.

 

Since we also need Gunicorn (Green Unicorn) which is a Web Server Gateway Interface (WSGI) primarily used to run flask applications.

 

 

 

pip install flask request gunicorn

 

 

 

 

 

 

 

 

Writing Flask app

 

Since we have all the dependencies installed to get started writing our flask application. Let's start with creating a new file - say main.py.

 

Let's add the following contents.

 

 

 

from flask import Flask
app = Flask(__name__)
 
@app.route('/')
def index():
  return '<h1>Hello World</h1>'

if __name__ == "__main__":
    app.run(debug=True, port=5000)

 

 

 

Running flask application

 

 

 

You can locally test your application by running the following command.

 

 

 

python main.py

 

 

 

 

4. Preparing to Deploy flask app to Heroku

 

Our flask application is ready now we just need to deploy it to Heroku.

 

 

 

Creating requirements.txt

 

 

 

Now let's freeze all the requirements inside requirements.txt by executing the below command on the command line.

 

 

 

pip freeze > requirements.txt

 

 

 

We are doing this for making sure that all of the required packages are installed while deploying the application.

 

 

 

Creating a Procfile for Gunicorn

 

 

 

For deploying the application on Heroku, we need to include a Procfile inside our project root directory. This will specify the command that is needed on startup for the execution by the app.

 

We can create a Procfile by executing the following command.

 

 

 

web: gunicorn <app_name>:app

 

 

 

Since in our case, the starting point of the application name is main.py. So we need to write- web: gunicorn main:app

 

To create the Procfile from the command line. You can simply execute the following command.

 

echo web: gunicorn main:app >> Procfile

 

 

 

5. Deploying flask application to Heroku Platform.

 

 

 

Login via Heroku CLI

 

 

 

First and foremost, we need to log in to Heroku.

 

 

 

heroku login

 

 

 

 

 

Creating Heroku App

 

 

 

You can create a Heroku app in 2 ways. One is via GUI and another one is via CLI.

 

 

 

Graphical Way:

 

From GUI you can create an application by visiting https://dashboard.heroku.com/new-app

 

 

 

 

CLI Way:

 

 

 

From CLI you can create an application by executing the following command on your terminal.

 

 

 

heroku create <app-name>

 

 

 

Deploy flask app to Heroku via git

 

Adding Heroku App to Remote:

 

git init
heroku git:remote -a <app-name>
git remote -v

 

Deploying:

 

 

 

git add .
git commit -m "Intial Commit"
git push heroku master

 

 

 

 

 

That's it for the tutorial of the "Deploy flask app to Heroku". Now your application should be live.

 

 

 

6. Deploying Heroku app via Github:

 

Instead of Heroku Git, you can also deploy your application to Heroku via Github.

 

You can push the existing Heroku application to Git Repository on Github by the following command:

 

 

 

git add .
git commit -m "Initial Commit"
git remote add origin <Remote Github Repository>
git branch -M main
git push -u origin main

 

 

 

After this, you can deploy your application from the Heroku GUI, following Github as a Deployment method. 

 

 

If you have any questions or suggestions regarding this article, please feel free to write in the comment section below. We have also some interesting articles on Linux - Best Linux Distros that you should try in 2021.