Build a containerized Python web app in the cloud

This article is part of a tutorial about how to containerize and deploy a Python web app to Azure App Service. App Service enables you to run containerized web apps and deploy through continuous integration/continuous deployment (CI/CD) capabilities with Docker Hub, Azure Container Registry, and Visual Studio Team Services. In this part of the tutorial, you learn how to build the containerized Python web app in the cloud.

In the previous optional part of this tutorial, a container image was build and run locally. In contrast, in this part of the tutorial, you build (containerize) a Python web app into a Docker image directly in Azure Container Registry. Building the image in Azure is typically faster and easier than building locally and then pushing the image to a registry. Also, building in the cloud doesn't require Docker to be running in your dev environment.

Once the Docker image is in Azure Container Registry, it can be deployed to Azure App service.

The service diagram shown below highlights the components covered in this article.

A screenshot of the services using in the Tutorial - Containerized Python App on Azure with the build-in-cloud path highlighted.

1. Create an Azure Container Registry

If you already have an Azure Container Registry you can use, go to the next step. If you don't, create one.

Azure CLI commands can be run in the Azure Cloud Shell or on a workstation with the Azure CLI installed. When running in Cloud Shell, skip Step 3.

Step 1. Create a resource group if needed with the az group create command. If you've already set up an Azure Cosmos DB for MongoDB account in part 2. Build and test container locally of this tutorial, set RESOURCE_GROUP_NAME to the name of the resource group you used for that account and move on to Step 2.

RESOURCE_GROUP_NAME='msdocs-web-app-rg'
LOCATION='eastus'

az group create -n $RESOURCE_GROUP_NAME -l $LOCATION

LOCATION should be an Azure location value. Choose a location near you. You can list Azure location values with the following command: az account list-locations -o table.

Step 2. Create a container registry with the az acr create command.

REGISTRY_NAME='<your Azure Container Registry name>'

az acr create -g $RESOURCE_GROUP_NAME -n $REGISTRY_NAME --sku Basic

REGISTRY_NAME must be unique within Azure and contain 5-50 alphanumeric characters.

In the JSON output of the command look for the loginServer value, which is the fully qualified registry name (all lowercase) and which should include the registry name you specified.

Step 3. If you're running the Azure CLI locally, log in to the registry using the az acr login command.

az acr login -n $REGISTRY_NAME

The command adds "azurecr.io" to the name to create the fully qualified registry name. If successful, you'll see the message "Login Succeeded".

Note

The az acr login command isn't needed or supported in Cloud Shell.

2. Build an image in Azure Container Registry

You can build the container image directly in Azure in a few ways. First, you can use the Azure Cloud Shell, which builds the image without using your local environment at all. You can also build the container image in Azure from your local environment using VS Code or the Azure CLI. Building the image in the cloud doesn't require Docker to be running in your local environment. If you need to, you can follow the instructions in Clone or download the sample app in part 2 of this tutorial to get the sample Flask or Django web app.

Azure CLI commands can be run on a workstation with the Azure CLI installed or in Azure Cloud Shell. When running in Cloud Shell, skip Step 1.

Step 1. If you're running the Azure CLI locally, log into registry if you haven't done so already with the az acr login command.

az acr login -n $REGISTRY_NAME

If you're accessing the registry from a subscription different from the one in which the registry was created, use the --suffix switch.

Note

The az acr login command isn't needed or supported in Cloud Shell.

Step 2. Build the image with the az acr build command.

az acr build -r $REGISTRY_NAME -g $RESOURCE_GROUP_NAME -t msdocspythoncontainerwebapp:latest .

In this command:

Step 3. Confirm the container image was created with the az acr repository list command.

az acr repository list -n $REGISTRY_NAME

Next step