IE Bank backend

• IE Bank backend
  • Overview
  • Requirements
  • Recommended tutorials
  • Configure your local environment
  • Install Prerequisites
  • Set up your local environment with VSCode
  • Run and debug the backend locally
  • Configuration variables
  • Continuos Delivery
  • GitHub secrets

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Overview

This is the repository for the backend code of the IE Bank web app

Requirements

This source code works under the following technologies:

• Python 3.11.5
• Flask 2.2.2
• Flask-Cors 3.0.10
• Flask-SQLAlchemy 2.5.1
• psycopg2 2.9.7
• python-dotenv 0.21.0
• SQLAlchemy 1.4.41
• SQL Lite 3.43.0

Recommended tutorials

• Flask
• Flask on VS Code
• Linkedin Learning: Building RESTful APIs with Flask
• SQLite

Configure your local environment

Install Prerequisites

• Install git. Install git from here.
• Install Python. Install Python 3.11.5 from here. Make sure to select the option to add Python to your PATH while installing.
• Install VSCode. Install VSCode from here.
• Install Python VSCode extension. Install the Python extension for VSCode from here.
• Install SQL Lite. Install SQL Lite from here. SQLite provides various tools for working across platforms e.g., Windows, Linux, and Mac. You need to select an appropriate version to download. After downloading:
  • On Windows, unzip the downloaded file into a directory (e.g., C:\sqlite). Add the C:\sqlite directory to your PATH environment variable.
  • On Linux, open a terminal and run the command sudo apt-get install sqlite3.
  • On MacOS, open a terminal and run the command brew install sqlite3.

Set up your local environment with VSCode

1. Create the virtual environment. In VS Code, open the Command Palette (View > Command Palette or [Ctrl+Shift+P]). Then select the Python: Create Environment command to create a virtual environment in your workspace. Select venv and then the Python environment you want to use to create it.

2. Activate your virtual environment. After your virtual environment creation has been completed, run Terminal: Create New Terminal [Ctrl+Shift+ `]) from the Command Palette, which creates a terminal and automatically activates the virtual environment by running its activation script.
3. Install Flask in the virtual environment. In the VS Code Terminal, run the following command:

$ python -m pip install flask

You now have a self-contained environment ready for writing Flask code. VS Code activates the environment automatically when you use Terminal: Create New Terminal.

Run and debug the backend locally

1. Debug the app locally. In VS Code, switch to the Run and Debug view (using the left-side activity bar or Ctrl + Shift + D). You may see the message "To customize Run and Debug create a launch.json file". VS Code can create that for you if you click on the create a launch.json file link:

2. Set and run debug configuration for Flask. Select the link and VS Code will prompt for a debug configuration. Select Python and the Flask from the dropdown and VS Code will populate a new launch.json file in the .vscode folder with a Flask run configuration. The launch.json file contains a number of debugging configurations, each of which is a separate JSON object within the configuration array. Edit the .vscode/launch.json configuration file with the snippet below and save (Ctrl+S).

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
        {
            "name": "IE Bank Backend",
            "type": "python",
            "request": "launch",
            "module": "flask",
            "env": {
                "FLASK_APP": "app.py",
                "FLASK_DEBUG": "1",
                "ENV": "local",
                "DBUSER":"",
                "DBPASS":"",
                "DBHOST":"",
                "DBNAME":""
            },
            "args": [
                "run",
                "--no-debugger",
                "--no-reload"
            ],
            "jinja": true,
            "justMyCode": true
        }
    ]
}

3. Run and Debug your application locally. Set a breakpoint in any of the .py files. Go to the Debug view, select the 'Python: Flask' configuration, then press F5 or click the green play button.

Configuration variables

Learn more: Flask configuration handling

When running the application in VSCode, the .vscode/launch.json file well set environment variables as configured in the env section:

 "env": {
                "FLASK_APP": "app.py",
                "FLASK_DEBUG": "1",
                "ENV": "local"
            },

This python app will read the environment variables in the iebank_api\__init__.py file. This file will load different variables depending on the value of the ENV variable read in the running machine.

# Select environment based on the ENV environment variable
if os.getenv('ENV') == 'local':
    print("Running in local mode")
    app.config.from_object('config.LocalConfig')
elif os.getenv('ENV') == 'dev':
    print("Running in development mode")
    app.config.from_object('config.DevelopmentConfig')
elif os.getenv('ENV') == 'ghci':
    print("Running in github mode")
    app.config.from_object('config.GithubCIConfig')
else:
    print("Running in production mode")
    app.config.from_object('config.ProductionConfig')

The configuration that will be loaded is defined in the config.py file.

class LocalConfig(Config):
    basedir = os.path.abspath(os.path.dirname(__file__))
    SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir,'.db', 'local.db')
    DEBUG = True

class GithubCIConfig(Config):
    SQLALCHEMY_DATABASE_URI = 'sqlite:///test.db'
    DEBUG = True

class DevelopmentConfig(Config):
    SQLALCHEMY_DATABASE_URI = 'postgresql://{dbuser}:{dbpass}@{dbhost}/{dbname}'.format(
    dbuser=os.getenv('DBUSER'),
    dbpass=os.getenv('DBPASS'),
    dbhost=os.getenv('DBHOST'),
    dbname=os.getenv('DBNAME')
    )
    DEBUG = True

Database Migrations

If you have ran the backend before on your computer, most likely you will need to update the database schema instead of creating a new one. To handle these migrations in an efficient way, we set up migrations using Flask-Migrate to take care of this without running sql queries directly. To run the migrations:

1. Start your virtual environenmt: source .venv/bin/activate on mac, ./.venv/Scripts/activate on windows. Note: that ".venv" is the name of your virtual environment.
2. Install the requirements: pip install -r requirements.txt
3. Run flask db init to initialize the db migrations setup. After running this command, a "migrations" folder should be created.
4. Now, anytime the database schema is updated and needs a migration, run flask db migrate -m "<migration-message>"

Continuos Delivery

Learn more:

• Deploy to App Service using GitHub Actions
• Deploying Python to Azure App Service

The file .github/workflows/ie-bank-backend.yml contains the configuration for the CI/CD pipeline

GitHub secrets

The workflow uses the following GitHub secrets: