Introduction

This is a sample web application using Flask framework and SQLAlchemy to connect to a Postgres database. The whole application runs on Docker. The dependencies are available in a requirements.txt file which can be installed with pip.

Assuming Docker and docker-compose are installed, run docker-compose up to start the web application

Database

The database is mounted in the local directory data for persistence. The credentials are mapped in the docker-compose file. Database migrations are available in the migrations folder which are created using alembic.

Accessing the database container can be done with the command : docker-compose exec db /bin/bash -c "psql books books-user"

Setting up the database

Database tables can be setup by logging into the webapp container and running the database migrations and seed script.

Database migrations can be executed by

docker-compose exec webapp /bin/bash
flask db migrate -m "Create books and requests"
flask db upgrade

To seed the database:

docker-compose exec db /bin/bash
psql -U $POSTGRES_USER -d $POSTGRES_DB -a -f /home/sample-flask-app/seed_db.sql

You can verify that the tables are setup by access the Postgres shell in the db container and then using the command \dt. You should see 2 tables : books and requests.

Erasing the database

Delete the existing data folder and create an empty folder. You will have to re-seed the database to have any data.

Webapp

The application requires Python3 and will be available at http://localhost:5000 and can use any API client to test the URLs. My preference is Postman

The workspace can be setup locally for testing with

rm -rf env/
python3 -m venv env
source env/bin/activate
pip3 install -r requirements.txt

Test Data

curl -i http://localhost:5000 should display Hello World!