CD/CI Tutorial Sample Application

Description

This sample Python REST API application was written for a tutorial on implementing Continuous Integration and Delivery pipelines.

It demonstrates how to:

• Write a basic REST API using the Flask microframework
• Basic database operations and migrations using the Flask wrappers around Alembic and SQLAlchemy
• Write automated unit tests with unittest

Also:

• How to use GitHub Actions

Related article: https://medium.com/rockedscience/docker-ci-cd-pipeline-with-github-actions-6d4cd1731030

Requirements

• Python 3.8
• Pip
• virtualenv, or conda, or miniconda

The psycopg2 package does require libpq-dev and gcc. To install them (with apt), run:

$ sudo apt-get install libpq-dev gcc

Installation

With virtualenv:

$ python -m venv venv
$ source venv/bin/activate
$ pip install -r requirements.txt

With conda or miniconda:

$ conda env create -n ci-cd-tutorial-sample-app python=3.8
$ source activate ci-cd-tutorial-sample-app
$ pip install -r requirements.txt

Optional: set the DATABASE_URL environment variable to a valid SQLAlchemy connection string. Otherwise, a local SQLite database will be created.

Initalize and seed the database:

$ flask db upgrade
$ python seed.py

Running tests

Run:

$ python -m unittest discover

Running the application

Running locally

Run the application using the built-in Flask server:

$ flask run

Running on a production server

Run the application using gunicorn:

$ pip install -r requirements-server.txt
$ gunicorn app:app

To set the listening address and port, run:

$ gunicorn app:app -b 0.0.0.0:8000

Running on Docker

Run:

$ docker build -t ci-cd-tutorial-sample-app:latest .
$ docker run -d -p 8000:8000 ci-cd-tutorial-sample-app:latest

Deploying to Heroku

Run:

$ heroku create
$ git push heroku master
$ heroku run flask db upgrade
$ heroku run python seed.py
$ heroku open

or use the automated deploy feature:

For more information about using Python on Heroku, see these Dev Center articles:

• Python on Heroku