Deploy a Python (Django or Flask) web app with PostgreSQL in Azure

• An Azure account with an active subscription. If you don't have an Azure account, you can create a trial account.
• Knowledge of Python with Flask development or Python with Django development

• An Azure account with an active subscription. If you don't have an Azure account, you can create a trial account.
• Azure Developer CLI installed. You can follow the steps with the Azure Cloud Shell because it already has Azure Developer CLI installed.

1. Create App Service and PostgreSQL

git clone https://github.com/Azure-Samples/msdocs-flask-postgresql-sample-app.git

git clone https://github.com/Azure-Samples/msdocs-django-postgresql-sample-app.git

In this step, you create the Azure resources. The steps used in this tutorial create a set of secure-by-default resources that include App Service and Azure Database for PostgreSQL. For the creation process, you'll specify:

• The Name for the web app. It's the name used as part of the DNS name for your webapp in the form of https://<app-name>.chinacloudsites.cn.
• The Region to run the app physically in the world.
• The Runtime stack for the app. It's where you select the version of Python to use for your app.
• The Hosting plan for the app. It's the pricing tier that includes the set of features and scaling capacity for your app.
• The Resource Group for the app. A resource group lets you group (in a logical container) all the Azure resources needed for the application.

Sign in to the Azure portal and follow these steps to create your Azure App Service resources.

2. Verify connection settings

The creation wizard generated the connectivity variables for you already as app settings. App settings are one way to keep connection secrets out of your code repository. When you're ready to move your secrets to a more secure location, here's an article on storing in Azure Key Vault.

3. Deploy sample code

In this step, you'll configure GitHub deployment using GitHub Actions. It's just one of many ways to deploy to App Service, but also a great way to have continuous integration in your deployment process. By default, every git push to your GitHub repository will kick off the build and deploy action.

Having issues? Check the Troubleshooting guide.

4. Generate database schema

5. Browse to the app

6. Stream diagnostic logs

Azure App Service captures all messages output to the console to help you diagnose issues with your application. The sample app includes print() statements to demonstrate this capability as shown below.

@app.route('/', methods=['GET'])
def index():
    print('Request for index page received')
    restaurants = Restaurant.query.all()
    return render_template('index.html', restaurants=restaurants)

def index(request):
    print('Request for index page received')
    restaurants = Restaurant.objects.annotate(avg_rating=Avg('review__rating')).annotate(review_count=Count('review'))
    return render(request, 'restaurant_review/index.html', {'restaurants': restaurants})

Learn more about logging in Python apps in the series on setting up Azure Monitor for your Python application.

7. Clean up resources

When you're finished, you can delete all of the resources from your Azure subscription by deleting the resource group.

1. Create Azure resources and deploy a sample app

In this step, you create the Azure resources and deploy a sample app to App Service on Linux. The steps used in this tutorial create a set of secure-by-default resources that include App Service and Azure Database for PostgreSQL.

1. If you haven't already, clone the sample repository's starter-no-infra branch in a local terminal.

   • Flask
   • Django

   git clone -b starter-no-infra https://github.com/Azure-Samples/msdocs-flask-postgresql-sample-app
   cd msdocs-flask-postgresql-sample-app
   

   This cloned branch is your starting point. It contains a simple data-drive Flask application.

2. From the repository root, run azd init.

   azd init --template python-app-service-postgresql-infra
   

3. When prompted, give the following answers:

   Question	Answer
   The current directory is not empty. Would you like to initialize a project here in '<your-directory>'?	Y
   What would you like to do with these files?	Keep my existing files unchanged
   Enter a new environment name	Type a unique name. The azd template uses this name as part of the DNS name of your web app in Azure (<app-name>.chinacloudsites.cn). Alphanumeric characters and hyphens are allowed.

4. Run the azd up command to provision the necessary Azure resources and deploy the app code. If you are not already signed-in to Azure, the browser will launch and ask you to sign-in. The azd up command will also prompt you to select the desired subscription and location to deploy to.

   azd up
   

   The azd up command might take a few minutes to complete. It also compiles and deploys your application code, but you'll modify your code later to work with App Service. While it's running, the command provides messages about the provisioning and deployment process, including a link to the deployment in Azure. When it finishes, the command also displays a link to the deploy application.

   This azd template contains files (azure.yaml and the infra directory) that generate a secure-by-default architecture with the following Azure resources:

   • Flask
   • Django

   • Resource group → The container for all the created resources.
   • App Service plan → Defines the compute resources for App Service. A Linux plan in the B1 tier is specified.
   • App Service → Represents your app and runs in the App Service plan.
   • Virtual network → Integrated with the App Service app and isolates back-end network traffic.
   • Azure Database for PostgreSQL flexible server → Accessible only from within the virtual network. A database and a user are created for you on the server.
   • Private DNS zone → Enables DNS resolution of the PostgreSQL server in the virtual network.
   • Log Analytics workspace → Acts as the target container for your app to ship its logs, where you can also query the logs.

2. Use the database connection string

The azd template you use generated the connectivity variables for you already as app settings and outputs the them to the terminal for your convenience. App settings are one way to keep connection secrets out of your code repository.

1. In the azd output, find the app settings and find the settings AZURE_POSTGRESQL_CONNECTIONSTRING and AZURE_REDIS_CONNECTIONSTRING. To keep secrets safe, only the setting names are displayed. They look like this in the azd output:

    App Service app has the following settings:
   
            - AZURE_POSTGRESQL_CONNECTIONSTRING
            - AZURE_REDIS_CONNECTIONSTRING
            - FLASK_DEBUG
            - SCM_DO_BUILD_DURING_DEPLOYMENT
            - SECRET_KEY
    

2. AZURE_POSTGRESQL_CONNECTIONSTRING contains the connection string to the Postgres database in Azure, and AZURE_REDIS_CONNECTIONSTRING contains the connection string to the Redis cache in Azure. You need to use them your code to connect to it. Open azureproject/production.py, uncomment the following lines, and save the file:

   • Flask
   • Django

   conn_str = os.environ['AZURE_POSTGRESQL_CONNECTIONSTRING']
   conn_str_params = {pair.split('=')[0]: pair.split('=')[1] for pair in conn_str.split(' ')}
   DATABASE_URI = 'postgresql+psycopg2://{dbuser}:{dbpass}@{dbhost}/{dbname}'.format(
       dbuser=conn_str_params['user'],
       dbpass=conn_str_params['password'],
       dbhost=conn_str_params['host'],
       dbname=conn_str_params['dbname']
   )
   

   Your application code is now configured to connect to the PostgreSQL database in Azure. If you want, open app.py and see how the DATABASE_URI environment variable is used.

3. In the terminal, run azd deploy.

   azd deploy
   

4. Generate database schema

With the PostgreSQL database protected by the virtual network, the easiest way to run Flask database migrations is in an SSH session with the App Service container.

5. Browse to the app

1. In the azd output, find the URL of your app and navigate to it in the browser. The URL looks like this in the AZD output:

    Deploying services (azd deploy)
   
      (✓) Done: Deploying service web
      - Endpoint: https://<app-name>.chinacloudsites.cn/
    

2. Add a few restaurants to the list.

   • Flask
   • Django

   

   Congratulations, you're running a web app in Azure App Service, with secure connectivity to Azure Database for PostgreSQL.

6. Stream diagnostic logs

Azure App Service can capture console logs to help you diagnose issues with your application. For convenience, the azd template has already enabled logging to the local file system as well as shipping them to a Log Analytics workspace.

The sample app includes print() statements to demonstrate this capability as shown in the following snippet.

@app.route('/', methods=['GET'])
def index():
    print('Request for index page received')
    restaurants = Restaurant.query.all()
    return render_template('index.html', restaurants=restaurants)

def index(request):
    print('Request for index page received')
    restaurants = Restaurant.objects.annotate(avg_rating=Avg('review__rating')).annotate(review_count=Count('review'))
    lastViewedRestaurant = request.session.get("lastViewedRestaurant", False)

In the azd output, find the link to stream App Service logs and navigate to it in the browser. The link looks like this in the azd output:

Stream App Service logs at: https://portal.azure.cn/#@/resource/subscriptions/<subscription-guid>/resourceGroups/<group-name>/providers/Microsoft.Web/sites/<app-name>/logStream

Learn more about logging in Python apps in the series on setting up Azure Monitor for your Python application.

7. Clean up resources

To delete all Azure resources in the current deployment environment, run azd down.

azd down