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tutorial-python-managed-identity-06.md

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title 6. Deploy to Azure
description Final configuration and deployment of a Python (Django or Flask) web app to Azure that uses managed identity to access to Azure Storage and PostgreSQL.
author jess-johnson-msft
ms.author jejohn
ms.devlang python
ms.topic tutorial
ms.date 06/01/2022
ms.prod azure-python
ms.custom devx-track-python, devx-track-azurecli

Deploy and configure the Python web app in Azure

This article is part of a tutorial about deploying a Python app to Azure App Service. The web app uses managed identity to authenticate to other Azure resources. In this article, you'll deploy the Python app to Azure and configure it. Configuration requires changes to the App Service and Azure Database for PostgreSQL service.

:::image type="content" source="./media/python-web-app-managed-identity/system-diagram-local-to-deploy-python-managed-identity-deploy-800px.png" lightbox="./media/python-web-app-managed-identity/system-diagram-local-to-deploy-python-managed-identity-deploy.png" alt-text="A screenshot showing the Azure services in the tutorial used with deployment to Azure highlighted." :::

1. Configure the web app in Azure

With the web app, storage account, and PostgreSQL database resources created, the next step is to tell the web app how to connect to the Azure Storage account and Azure Database for PostgreSQL service.

The Python code uses environment variables named DBHOST, DBNAME, DBUSER, STORAGE_ACCOUNT_NAME, and STORAGE_CONTAINER_NAME to connect to the storage and database resources. You don't specify an access key for storage or a password for the database because authentication is handled by managed identity.

Azure portal

Instructions Screenshot
[!INCLUDE Azure portal connect app to postgres step 1] :::image type="content" source="./media/python-web-app-managed-identity/connect-postgres-to-app-azure-portal-1-240px.png" lightbox="./media/python-web-app-managed-identity/connect-postgres-to-app-azure-portal-1.png" alt-text="A screenshot showing how to navigate to App Settings in the Azure portal." :::
[!INCLUDE Azure portal connect app to postgres step 2] :::image type="content" source="./media/python-web-app-managed-identity/connect-postgres-to-app-azure-portal-2-240px.png" lightbox="./media/python-web-app-managed-identity/connect-postgres-to-app-azure-portal-2.png" alt-text="A screenshot showing how to configure the App Settings in the Azure portal." :::

VS Code

To configure environment variables for the web app from VS Code, you must have the Azure Tools extension pack installed and be signed into Azure from VS Code.

Instructions Screenshot
[!INCLUDE VS Code connect app to postgres step 1] :::image type="content" source="./media/python-web-app-managed-identity/connect-app-to-database-create-setting-240px.png" lightbox="./media/python-web-app-managed-identity/connect-app-to-database-create-setting.png" alt-text="A screenshot showing how to add a setting to the App Service in VS Code." :::
[!INCLUDE VS Code connect app to postgres step 2]

Azure CLI

[!INCLUDE Connect web app to postgres service with CLI]

2. Enable web app to access the database

You created and configured an Azure Database for PostgreSQL server in a previous step. In this step, you'll add a firewall rule that allows the web app to access to the database server. You can add a firewall rule with the Azure portal or the Azure CLI.

If you're working in VS Code, right-select the database server and select Open in Portal and follow the portal instructions. Or, go to the Azure Cloud Shell and run the Azure CLI commands.

Azure portal

Instructions Screenshot
[!INCLUDE A screenshot showing the location and adding a firewall rule in the Azure portal] :::image type="content" source="./media/python-web-app-managed-identity/add-access-to-postgres-from-web-app-portal-1-240px.png" lightbox="./media/python-web-app-managed-identity/add-access-to-postgres-from-web-app-portal-1.png" alt-text="A screenshot showing how to add access from other Azure services to a PostgreSQL database in the Azure portal." :::

Azure CLI

[!INCLUDE Allow access from web app to postgres service with CLI]

3. Deploy the Python web app to Azure

Azure App Service supports multiple ways to deploy your application code to Azure including support for GitHub Actions and all major CI/CD tools. This article focuses on how to deploy your code from your local workstation to Azure.

Deploy using VS Code

To deploy a web app from VS Code, you must have the Azure Tools extension pack installed and be signed into Azure from VS Code.

Instructions Screenshot
[!INCLUDE VS Code deploy step 1]
[!INCLUDE VS Code deploy step 2] :::image type="content" source="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-1-240px.png" lightbox="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-1.png" alt-text="A screenshot showing how to deploy a web app in VS Code." :::
[!INCLUDE VS Code deploy step 3] :::image type="content" source="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-3-240px.png" lightbox="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-3.png" alt-text="A screenshot showing how to deploy a web app in VS Code: a dialog box to confirm deployment." :::
[!INCLUDE VS Code deploy step 4] :::image type="content" source="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-4-240px.png" lightbox="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-4.png" alt-text="A screenshot showing how to deploy a web app in VS Code: a dialog box to choose to always deploy to the app service." :::
[!INCLUDE VS Code deploy step 5] :::image type="content" source="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-5-240px.png" lightbox="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-5.png" alt-text="A screenshot showing how to deploy a web app in VS Code: a dialog box with choice to browse to website." ::: :::image type="content" source="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-6-240px.png" lightbox="./media/python-web-app-managed-identity/deploy-web-app-visual-studio-code-6.png" alt-text="A screenshot showing how to deploy a web app in VS Code: a dialog box with choice to view deployment details." :::

Deploy using Local Git

[!INCLUDE Deploy Local Git]

Deploy using a ZIP file

[!INCLUDE Deploy using ZIP file]

4. Create the database schema

With the code deployed and the database in place, the app is almost ready to use. As a final step, you need to establish the necessary schema in the database. You create the schema by "migrating" the data models stored with the app code to the PostgreSQL database.

Step 1. Create an SSH session and connect to web app server.

Azure portal

Navigate to page for the App Service instance in the Azure portal.

  1. Select SSH, under Development Tools on the left resource menu.
  2. Then Go to open an SSH console on the web app server. (It may take a minute to connect for the first time as the web app container needs to start.)

VS Code

In VS Code, you can use the Azure Tools extension pack to create an SSH session. You must be signed into Azure from VS Code.

In the App Services section of the Azure Tools extension:

  1. Locate your web app and right-click to bring up the context menu. (Make sure you viewing resources by Group by Resource Type.)
  2. Select SSH into Web App to open an SSH terminal window.

Azure CLI

[!INCLUDE Deploy local git with CLI]

If you can't connect with SSH, see Troubleshooting tips.

Step 2. In the SSH session, run commands to migrate the models into the database:

Flask

# Create database tables
flask db init

When you deploy the Flask sample app to Azure App Service, the database tables will likely be created automatically in Azure Database for PostgreSQL server. If the tables schema exists, the command above returns the message "Directory migrations already exists and is not empty." If so, the migration was performed during deployment. Go to the next step.

Django

# Create database tables
python manage.py migrate

If you can't migrate the models, see Troubleshooting tips.

Tip

In an SSH session, for Django you can also create users with the python manage.py createsuperuser command like you would with a typical Django app. For more information, see the documentation for django django-admin and manage.py. Use the superuser account to access the /admin portion of the web site. For Flask, use an extension such as Flask-admin to provide the same functionality.

5. Test the Python web app in Azure

The sample Python app uses the azure.identity package and DefaultAzureCredentialClass. The DefaultAzureCredential automatically detects that a managed identity exists for the App Service and uses it to access other Azure resources (storage and Postgres in this case). There's no need to provide storage keys, certificates, or credentials to the App Service to access these resources.

Browse to the deployed application at the URL http://<app-name>.azurewebsites.net. It can take a minute or two for the app to start. If you see a default app page that isn't the default sample app page, wait a minute and refresh the browser.

To test the functionality of the sample app, add a restaurant and then add some reviews with photos for the restaurant. The restaurant and review information is stored in Azure Database for PostgreSQL and the photos are stored in Azure Storage. Here's an example screenshot:

:::image type="content" source="./media/python-web-app-managed-identity/example-of-review-sample-app-production-deployed-small.png" lightbox="./media/python-web-app-managed-identity/example-of-review-sample-app-production-deployed.png" alt-text="An example of the sample app showing restaurant review functionality using Azure App Service, Azure PostgreSQL Database, and Azure Storage." :::

6. Troubleshooting tips

Here are a few tips for troubleshooting your deployment:

  • When you deploy Python code to App Service, a built-in Linux container is created to run the web app. If a deployment isn't successful, in the Azure portal check the Deployment Center | Logs generated during the build of the container to confirm the deployment failed. If there was a failure, go to the Diagnose and solve problems resource of the App Service to check the diagnostic logging. The Application logging logs are the most useful for troubleshooting failed deployments. Be sure to check the timestamp of the logging entries to make sure they correspond to the deployment you're troubleshooting. There may be a delay in writing the logs and you might need to wait to see the logging information for the deployment.

  • If you encounter errors related to connecting to the database while doing the migration, check the values of the application settings of the App Service, specifically DBHOST, DBNAME, and DBUSER. Without these settings, the web app can't communicate with the database.

  • If you have the database connection information correctly specified, confirm that you set up managed identity for the database correctly.

  • If you can't open an SSH session to connect to your Azure App Service, then the app might have failed to start. Check the diagnostic logs for details, and in particular, the application logs. Errors can occur for many reasons. For example, if you haven't created the necessary app settings in the previous section, the logs will indicate KeyError: 'DBNAME'.

  • Check that there's an App Service configuration setting SCM_DO_BUILD_DURING_DEPLOYMENT set to true or 1. For more information and background on how Azure App Service runs Python apps, see Configure a Linux Python app for Azure App Service.

  • If you're deploying to App Service using local Git and you specified the wrong credentials, it might get cached and you need to clear these credentials. For more information about Git credentials, see Git Tools - Credential Storage. On Windows, you can open the Credential Manager / Windows Credentials, find the credentials and remove it.

  • If deployment is successful and the web app is running, print statements in the code write to the log stream. In the Azure portal, go to the App Service and open the Log Stream resource. For more information, see Enable diagnostics logging for apps in Azure App Service - Stream logs.

Next step

[!div class="nextstepaction"] Clean up resources >>>