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Python (Flask) Web App with PostgreSQL

Artists Booking Venues powered by Python (Flask) and PostgreSQL Database. There is no user authentication or per-user data stored.

Screenshot of website landing page

The project is designed for deployment on Azure App Service with a PostgreSQL flexible server. See deployment instructions below.

Open in GitHub Codespaces

Architecture Diagram: App Service, PostgreSQL server.

Local Development

  1. Download the project starter code locally

    git clone https://github.com/john0isaac/flask-webapp-postgresql-db.git
cd flask-webapp-postgresql-db

  2. Initialize and activate a virtualenv using:

    python -m virtualenv venv
source venv/bin/activate

    Note - In Windows, the venv does not have a bin directory. Therefore, you'd use the analogous command shown below:

    source venv/Scripts/activate
deactivate

  3. Install the dependencies:

    pip install -r requirements.txt

  4. Run the development server:

    export FLASK_APP=app.py
export FLASK_ENV=development
export FLASK_DEBUG=true
flask run --reload

  5. Verify on the Browser

Navigate to project homepage http://127.0.0.1:5000/ or http://localhost:5000

Azure Deployment

This repository is set up for deployment on Azure App Service (w/PostgreSQL flexible server) using the configuration files in the infra folder.

To deploy your own instance, follow these steps:

  1. Sign up for a free Azure account

  2. Install the Azure Dev CLI.

  3. Initialize a new azd environment:

    azd init

    It will prompt you to provide a name (like "flask-app") that will later be used in the name of the deployed resources.

  4. Provision and deploy all the resources:

    azd up

    It will prompt you to login, pick a subscription, and provide a location (like "eastus"). Then it will provision the resources in your account and deploy the latest code. If you get an error with deployment, changing the location (like to "centralus") can help, as there may be availability constraints for some of the resources.

  5. When azd has finished deploying, you'll see an endpoint URI in the command output. Visit that URI to browse the app! 🎉

If you make any changes to the app code, you can just run this command to redeploy it:

azd deploy

Security

It is important to secure the databases in web applications to prevent unwanted data access. This infrastructure uses the following mechanisms to secure the PostgreSQL database:

  • Azure Firewall: The database is accessible only from other Azure IPs, not from public IPs. (Note that includes other customers using Azure).
  • Admin Username: A unique string generated based on the resource name (not random, but not a standard name, either).
  • Admin Password: Randomly generated and updated on each deploy.
  • PostgreSQL Version: Latest available on Azure, version 14, which includes security improvements.

⚠️ For even more security, consider using a Key Vault to store your database username and password plus an Azure Virtual Network to connect the Web App to the Database.

Costs

Pricing varies per region and usage, so it isn't possible to predict exact costs for your usage.

You can try the Azure pricing calculator for the resources:

  • Azure App Service: Free Tier with shared CPU cores, 1 GB RAM. Pricing
  • PostgreSQL Flexible Server: Burstable Tier with 1 CPU core, 32GB storage. Pricing is hourly. Pricing

⚠️ To avoid unnecessary costs, remember to take down your app if it's no longer in use, either by deleting the resource group in the Portal or running azd down.

Google Cloud Deployment

  1. Open the Google Cloud Shell and execute the following command:

    git clone https://github.com/john0isaac/flask-webapp-postgresql-db.git
cd flask-webapp-postgresql-db

  2. Create the env_variables.yaml file that contains your secret environment variables.

    nano env_variables.yaml

  3. Add your Google Cloud SQL database connection details

    env_variables:
  DB_USER_NAME: 'secret'
  DB_PASSWORD: 'secret'
  DB_NAME: 'secret'
  DB_HOST: '111.111.111.111'
  DB_PORT: '5432'
  DB_CONNECTOR: 'postgresql+pg8000'
  INSTANCE_UNIX_SOCKET: '/cloudsql/Connection name'
  DEPLOYMENT_LOCATION: 'gcp'

  4. save and exit the file CTRL+x followed by y followed by Enter.

  5. Deploy the web application.

    gcloud app deploy app.yaml

Deploying After Deleting Everything from Google Cloud

  1. Create a Cloud SQL instance using the following parameters:

    • Specify instance name and password.
    • Select production instead of production plus.
    • Select Single Zone.
    • Specify the machine configuration of 2 vCPUs and 8 GB Memory.
    • Select the smallest storage option available 10 GB.
    • Add your IP to the Instance Network.
    • Select Create.
    • Create a database and call it fyyur.
    • Create a user and call it john.
    • Grant All privileges to user john.

  2. Import Data dump.

  3. Pull the code to the Cloud Shell.

  4. Create environment variables .yaml file.

  5. Enable App Engine.

  6. execute the following command gcloud beta app repair.

  7. execute the following command gcloud app deploy --no-cache.