Introduction

The project is backend flask CRUD project - Pizza order and deliever system. In development, I used SQLite as my database. There are two relational talbes, users and orders. In user table, it included id, username, email, password, is_staff, is_active. In orders table, it included order_id, pizza_size, order_status, pizza_flavour, qutity, cutormer_id. I used flask-sqlalchemy to create the database and flask-migrate to migrate the database.
If you're interested in viewing more about Flask, check out my repo on how to build, test, and deploy a Flask app.

Some technologies in this projects

• Flask
• Flask-SQLAlchemy
• Postgres
• Gunicorn - Python WSGI HTTP Server
• psycopg2 - PostgreSQL database adapter for Python
• Render - Deploy and host your web app

Check out the details about Render

Transfrom database from SQLite to Postgres

Used HeidiSQL to connect to the Render server and generate DATABASE_URL, and also (but no need for this project) it can export the database to SQL file. (for example)

postgresql://flask_rest_api_project_user:O777qqqqqqqqqqqqqqqqqqqqq@dgg-cggggggggggggggggggg-a.oregon-postgres.render.com/

I didn't focus on how to work in dev and test environment in this post. After I finished dev and test in local successfully, I would deploy my project to Render website.

So from development to production, what I changed for developing this Flask project.

Prerequisites

In virtual environment,

# pip
(venv)$ pip install gunicorn
(venv)$ pip freeze > requirements.txt
(venv)$ pip install psycopg2-binary
(venv)$ pip freeze > requirements.txt

Production configuration

# config.py
import os
import re
...
from decouple import config

BASE_DIR=os.path.dirname(os.path.realpath(__file__))

uri = config("DATABASE_URL")  # or other relevant config var
if uri.startswith("postgres://"):
    uri = uri.replace("postgres://", "postgresql://", 1)
...
...
class ProdConfig(Config):
    SQLALCHEMY_DATABASE_URI=uri
    SQLALCHEMY_TRACK_MODIFICATIONS=False
    DEBUG=config('DEBUG',cast=bool)

config_dict={
    'dev':DevConfig,
    'testing':TestConfig,
    'prodution':ProdConfig
}

# runserver.py
from api import create_app
from api.config.config import config_dict
# change the config type from dev to prodution
app= create_app(config=config_dict['prodution'])

if __name__ == '__main__':
    app.run()

Database Initialization

In virtual environment,

 export DATABASE_URL=postgresql://flask_rest_api_project_user:O777qqqqqqqqqqqqqqqqqqqqq@dgg-cggggggggggggggggggg-a.oregon-postgres.render.com/flask_rest_api_project
# what means of this DATABASE_URL?
# Network type: PostgreSQL (TCP/IP)
# User name: flask_rest_api_project_user
# Password: O777qqqqqqqqqqqqqqqqqqqqq
# Hostname: dgg-cggggggggggggggggggg-a.oregon-postgres.render.com
# port: 5432

export FLASK_APP=api/
echo $FLASK_APP
flask shell
>>>db.create_all() # create tables

Render Deployment Steps

1. Web Service
   Start by creating a new account with Render (if you don't have one). Then, navigate to your dashboard, click on the "New +" button, and select "Web Service".
   Connect your Render account to either your GitLab or GitHub account. Once connected, select the repository to deploy.

2. Fill out the configuration for deploying the Web Service:
   
   • Environment: Python 3
   • Region: Oregon (us-west)
   • Branch: main
   • Build Command: pip install -r requirements.txt
   • Start Command: gunicorn runserver:app
     runserver.py is the file name, app is the variable name
3. Set Environment Variables
   
   • DATABASE_URL: postgresql://............... (your database url)
   • PYTHON_VERSION: 3.10.2 (My python version)
   • SECRET_KEY: (your secret key)
   • DEBUG: True
   • JWT_SECRET_KEY: (your jwt secret key)
   • CONFIG_TYPE: production
4. Check the deployment status by clicking on the "Events" tab
   You'll see that the "Deploy" is live once all the configuration changes are applied and the service is updated.

References

1. Developing RESTful APIs with Python and Flask
2. Ssali Jonathan Youtube Channel
3. Deploying a Flask App to Render
4. Render website

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