Prerequisites

To use this demo app:

• Install Python 3
• Install Docker Community Edition
• (Optional) Install the Azure CLI

Run locally

To build and run the docker container locally:

docker build --rm -t stackoverflow-flask .
docker run --rm -it -p 8000:8000 stackoverflow-flask

Open a web browser, and navigate to the sample app at http://localhost:8000.

In your terminal window, press Ctrl+C to exit the web server and stop the container.

If you make code changes you can re-run the docker build and run commands above to update the container.

Deploy the container to Azure

For this portion of the tutorial you will need the Azure CLI. Either install it locally, or you can run commands in the browser by navigating to the Azure Cloud Shell.

Create a resource group:

az group create --name FlaskApp --location "West US"

Create a container registry and retrieve the password, note that <registry_name> needs to be a unique name:

az acr create --name <registry_name> --resource-group FlaskApp --location "West US" --sku Basic --admin-enabled true
az acr credential show -n <registry_name>

You see two passwords. Make note of the user name and the first password.

{
  "passwords": [
    {
      "name": "password",
      "value": "<registry_password>"
    },
    {
      "name": "password2",
      "value": "<registry_password2>"
    }
  ],
  "username": "<registry_name>"
}

Log in to your registry. When prompted, supply the username and password shown above.

docker login <registry_name>.azurecr.io -u <registry_name>

Tag your container and push it to the registry:

docker tag flask-quickstart <registry_name>.azurecr.io/flask-quickstart
docker push <registry_name>.azurecr.io/flask-quickstart

Create the app service plan:

az appservice plan create --name FlaskAppPlan --resource-group FlaskApp --sku B1 --is-linux

Create the web app:

az webapp create --name <app_name> --resource-group FlaskApp --plan FlaskAppPlan --deployment-container-image-name "<registry_name>.azurecr.io/flask-quickstart"

Configure it to pull from the registry:

az webapp config container set --name <app_name> --resource-group FlaskApp --docker-custom-image-name <registry_name>.azurecr.io/flask-quickstart --docker-registry-server-url https://<registry_name>.azurecr.io --docker-registry-server-user <registry_name> --docker-registry-server-password <registry_password>

Run the following command to set the port number on the site and restart it:

az webapp config appsettings set --name <app name> --resource-group FlaskApp --settings  WEBSITES_PORT=8000
az webapp restart --name <app name> --resource-group FlaskApp

Browse to the web app at http://<app_name>.azurewebsites.net

Install additional libraries

To install additional libraries, first create a virtual environment locally, install packages and then generate a requirements.txt file.

On Windows:

py -3 -m venv env
env\scripts\activate
pip install flask <list of other libraries>
pip freeze > requirements.txt
deactivate

On Linux/Unix/macOS:

python3 -m venv env
env/bin/activate
pip install flask <list of other libraries>
pip freeze > requirements.txt
deactivate

Add the following code to the dockerfile so that the additional requirements are installed:

# Install additional requirements from a requirements.txt file
COPY requirements.txt /
RUN pip install --no-cache-dir -U pip
RUN pip install --no-cache-dir -r /requirements.txt

Clean up

To clean up your Azure resources, delete the resource group az group delete --name FlaskApp